Unix Admin. Horror Story Summary, version 1.0 ----------------------------------------- compiled by: Anatoly Ivasyuk (anatoly@nick.csh.rit.edu) This is version 1.0 of the unofficial "Unix Administration Horror Story Summary". This is a summary of the "Unix Administration Horror Stories" thread which was seen in comp.unix.admin in October '92. I put this together for two reasons: 1) Some of these stories are damn amusing. 2) Many people can learn many things about what *not* to do when they're in charge of a system. This summary contains quite a few different types of stories. There are success stories, and... well... other stories. But the most important thing that can be learned from this is not that you have to make backups (we all know that, right? ;-) ). More important than making backups is to make sure your backups are complete and verified. For more on this, see the story about trying to backup 300MB drives onto 150MB tapes. If there are additional stories that anyone wants to submit, I'll be glad to add them to this FAQ. Send them to me at: anatoly@nick.csh.rit.edu. Please send any general comments my way, also. Please consider this a "beta test" release. I have not had the time to go over this as many times as I wanted to, so there may be mistakes in my editing. I have not edited the content of the stories except where noted, and may have excluded stories or bits where I felt it was appropriate. -Anatoly ----------------------------------------------------------------------------- The posting that started it all: -------------------------------- On 7 Oct 92 12:02:46 GMT, aras@multix.no (Arne Asplem) said: > I'm the program chair for a one day conference on Unix system > administration in Oslo in 3 weeks, including topics like network > management, system admininistration tools, integration, print/file-servers, > securitym, etc. > I'm looking for actual horror stories of what have gone wrong because > of bad system administration, as an early morning wakeup. > I'll summarise to the net if there is any interest. > -- Arne ----------------------------------------------------------------------------- From: jdell@maggie.mit.edu (John Ellithorpe) Organization: Massachusetts Institute of Technology Here's a pretty bad story. I wanted to have root use tcsh instead of the Bourne shell. So I decided to copy tcsh to /usr/local/bin. I created the file, /etc/shells, and put in /usr/local/bin/tcsh, along with /bin/sh and /bin/csh. All seems fine, so I used the chsh command and changed root's shell to /usr/local/bin/tcsh. So I logged out and tried to log back in. Only to find out that I couldn't get back in. Every time I tried to log in, I only got the statement: /usr/local/bin/tcsh: permission denied! I instantly realized what I had done. I forgot to check that tcsh has execute privileges and I couldn't get in as root! After about 30 minutes of getting mad at myself, I finally figured out to just bring the system down to single-user mode, which ONLY uses the /bin/sh, thankfully, and edited the password file back to /bin/sh. I'll never do that again. This wasn't that much of a horror story, but good enough if you aren't that familiar with the system. John ----------------------------------------------------------------------------- From: dbrillha@dave.mis.semi.harris.com (Dave Brillhart) Organization: Harris Semiconductor We can laugh (almost) about it now, but... Our operations group, a VMS group but trying to learn UNIX, was assigned account administration. They were cleaning up a few non-used accounts like they do on VMS - backup and purge. When they came across the account "sccs", which had never been accessed, away it went. The "deleteuser" utility fom DEC asks if you would like to delete all the files in the account. Seems reasonable, huh? Well, the home directory for "sccs" is "/". Enough said :-( ----------------------------------------------------------------------------- From: tzs@stein.u.washington.edu (Tim Smith) Organization: University of Washington, Seattle I was working on a line printer spooler, which lived in /etc. I wanted to remove it, and so issued the command "rm /etc/lpspl." There was only one problem. Out of habit, I typed "passwd" after "/etc/" and removed the password file. Oops. I called up the person who handled backups, and he restored the password file. A couple of days later, I did it again! This time, after he restored it, he made a link, /etc/safe_from_tim. About a week later, I overwrote /etc/passwd, rather than removing it. After he restored it again, he installed a daemon that kept a copy of /etc/passwd, on another file system, and automatically restored it if it appeared to have been damaged. Fortunately, I finished my work on /etc/lpspl around this time, so we didn't have to see if I could find a way to wipe out a couple of filesystems... --Tim Smith ----------------------------------------------------------------------------- From: nickp@BNR.CA ("Nick Pitfield", N.T.) Greetings, The following horror story occured only last week.... One of my colleagues had been itching to get into sys admin for some time, so last week he was finally sent on a 5-day sys admin course run by HP in Bracknell.. On the following Sunday, he decided to try out his new found knowledge by trying to connect and configure a DAT drive on one of our critical test systems. He connected the cables up okay, and then created the device file using 'mknod'. Unfortunately, he gave the device file the same minor & major device numbers as the root disk; so as soon as he tried to write to this newly installed 'DAT drive', the machine wents tits up with a corrupt root disk....ho hum. Regards. Nick Pitfield. ----------------------------------------------------------------------------- From: philip@haas.berkeley.edu (Philip Enteles) Organization: Haas School of Business, Berkeley As a new system administrator of a Unix machine with limited space I thought I was doing myself a favor by keeping things neat and clean. One day as I was 'cleaning up' I removed a file called 'bzero'. Strange things started to happen like vi didn't work then the compliants started coming in. Mail didn't work. The compilers didn't work. About this time the REAL system administrator poked his head in and asked what I had done. Further examination showed that bzero is the zeroed memory without which the OS had no operating space so anything using temporary memory was non-functional. The repair? Well things are tough to do when most of the utilities don't work. Eventually the REAL system administrator took the system to single user and rebuilt the system including full restores from a tape system. The Moral is don't be to anal about things you don't understand. Take the time learn what those strange files are before removeing them and screwing yourself. Philip Enteles ----------------------------------------------------------------------------- From: broberts@waggen.twuug.com (Bill Roberts) Organization: Brite Systems My most interesting in the reguard was when I deleted "/dev/null". Of course it was soon recreated as a "regular file", then permission problems started to show up. I was new at the game at the time and couldn't figure out what happened! It look good to me. I didn't know about "special files" and "mknod" and major and minor device codes. A friend finally helped out and started laughing and put me on the right track. That one episode taught me a lot about my system. ----------------------------------------------------------------------------- From: Frank T Lofaro Organization: Sophomore, Math/Computer Science, Carnegie Mellon, Pittsburgh, PA Well one time I was installing a minimal base system of Linux on a friends PC, so that we would have all the necessary utlitities to bring over the rest of the stuff. His 3 1/2 inch disk was dead, so when had to get the 5 1/4 inch version of the boot/root disk. Too bad that version, having to fit in 1.2M instead of 1.44, didn't have tar. We could get a version of tar, but it was in a tar file (nice chicken and egg scenario). I said, okay, since we don't have tar, we can't use that to copy the files from floppy to the hard disk, I'll use cp instead (bad move). It actually seemed to work for a while, then the machine rebooted! I did it again, the same thing happened. Then I realize cp wouldn't work on device files! (this is what happens when you try to install un*x at 3 AM). It just read the contents of the device and made a file containing such, which is undesireable in any event. (when it read /dev/port, the device file that references I/O ports, it must've did something to reboot the machine, that was the file that was causing the reboots). I finally got it working by having him get the tar archive of the linux binaries (including the tar we needed), and untarring it on one of the public decstations here, so we could ftp tar to his PC using his dos tcp/ip stuff. A funny aside was that it untarred into ~/bin, and superseded all his normal commands. We were wondering why everything wouldn't run. Luckily it wasn't too hard to fix after we realized what happened. ----------------------------------------------------------------------------- From: mfraioli@grebyn.com (Marc Fraioli) Organization: Grebyn Timesharing Well, here's a good one for you: I was happily churning along developing something on a Sun workstation, and was getting a number of annoying permission denieds from trying to write into a directory heirarchy that I didn't own. Getting tired of that, I decided to set the permissions on that subtree to 777 while I was working, so I wouldn't have to worry about it. Someone had recently told me that rather than using plain "su", it was good to use "su -", but the implications had not yet sunk in. (You can probably see where this is going already, but I'll go to the bitter end.) Anyway, I cd'd to where I wanted to be, the top of my subtree, and did su -. Then I did chmod -R 777. I then started to wonder why it was taking so damn long when there were only about 45 files in 20 directories under where I (thought) I was. Well, needless to say, su - simulates a real login, and had put me into root's home directory, /, so I was proceeding to set file permissions for the whole system to wide open. I aborted it before it finished, realizing that something was wrong, but this took quite a while to straighten out. Marc Fraioli ----------------------------------------------------------------------------- From: rheiger@renext.open.ch (Richard H. E. Eiger) Organization: Olivetti (Schweiz) AG, Branch Office Berne In article <1992Oct9.100444.27928@u.washington.edu> tzs@stein.u.washington.edu (Tim Smith) writes: > I was working on a line printer spooler, which lived in /etc. I wanted > to remove it, and so issued the command "rm /etc/lpspl." There was only > one problem. Out of habit, I typed "passwd" after "/etc/" and removed > the password file. Oops. > [deleted to save space[ > > --Tim Smith Here's another story. Just imagine having the sendmail.cf file in /etc. Now, I was working on the sendmail stuff and had come up with lots of sendmail.cf.xxx which I wanted to get rid of so I typed "rm -f sendmail.cf. *". At first I was surprised about how much time it took to remove some 10 files or so. Hitting the interrupt key, when I finally saw what had happened was way to late, though. Fortune has it that I'm a very lazy person. That's why I never bothered to just back up directories with data that changes often. Therefore I managed to restore /etc successfully before rebooting... :-) Happy end, after all. Of course I had lost the only well working version of my sendmail.cf... Richard ----------------------------------------------------------------------------- From: mitch@cirrus.com (Mitch Wright) Organization: Cirrus Logic Inc. I guess I should add a story (or maybe not). Anyway, a fellow sysadmin was looking to free up some much needed disk space. Since it was purely a production machine I suggested that he go through and "strip" his binaries. Unfortunately I made the assumption that he knew what strip does and would use it wisely -- flashes of the Bad News Bears come to mind now. To make it short, he stripped /vmunix which didn't destroy the system, but certainly caused some interesting problems. ~mitch ----------------------------------------------------------------------------- From: hirai@cc.swarthmore.edu (Eiji Hirai) Organization: Information Services, Swarthmore College, Swarthmore, PA, USA Some of these stories of pure stupidity rather than of interesting horror but they did happen. [ BTW, these happened at a different place at a different time than where I am now. Don't bother my current employer about it. ] (1) A consultant we had hired (and not a very good one) was installing Unix on one our workstations. He was mucking with creating and deleting /dev/tty* files and made /dev/tty a regular file. Weird things started to happen. Commands would only print their output if you pressed return twice, etc. Fortunately, we solved the problem by re-mknod-ing /dev/tty. However, it took a while to realize what was causing this problem. (2) I wanted to create a second swap partition on another disk and made the partition start at sector 0 of the disk! (which sounded ok at the time since all other regular 'a' partitions started on sector 0) Every time I rebooted, fsck would complain about missing partition tables - I initially suspected that the disk was bad but I later realized that swapping was overwriting the partition table. I had lost an unknown percentage of the financial data for the institution that I was working for at the time, right when they were being audited! Yikes! Anyway, we were able to recover the data and life returned to normal but I did wonder at the time whether I could still keep my job there. (3) At the same institution, we were running a system software that had a serious bug where if anyone had logged out ungracefully, the system wouldn't let any more users onto the system and users who were logged on couldn't execute any new commands. (The newest release of the software later on did fix this bug.) I had to reboot the machine to restore the system to a sane state. I did a wall < hirai@cc.swarthmore.edu (Eiji Hirai) writes: >...[some deleted] >(4) I heard this from a fellow sysadmin friend. My friend was forced to >work with some sysadmins who didn't have their act together. One day, one >of them was "cleaning" the filesytem and saw a file called "vmunix" in /. >"Hmm, this is taking up a lot of space - let's delete it". "rm /vmunix". >My friend had to reinstall the entire OS on that machine after his coworker >did this "cleanup". Ahh, the hazards of working with sysadmins who really >shouldn't be sysadmins in the first place. When this happened to a colleague (when I worked somewhere else) he restored vmunix by copying from another machine. Unfortunately, a 68000 kernel does not run very well on a Sparc... ----------------------------------------------------------------------------- From: smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) Organization: SunConnect In article , hirai@cc.swarthmore.edu (Eiji Hirai) writes: > (4) I heard this from a fellow sysadmin friend. My friend was forced to > work with some sysadmins who didn't have their act together. One day, one > of them was "cleaning" the filesytem and saw a file called "vmunix" in /. > "Hmm, this is taking up a lot of space - let's delete it". "rm /vmunix". > > My friend had to reinstall the entire OS on that machine after his coworker > did this "cleanup". Ahh, the hazards of working with sysadmins who really > shouldn't be sysadmins in the first place. Hmm. A colleague of mine did much the same by accident on one of our test machines. After discovering it, fortunately while the machine was still up & running, he FTPed a copy of /vmunix from the other lab system (both running exactly the same kernel). After rebooting his machine everything (to his relief) worked fine. ----------------------------------------------------------------------------- From: lingnau@math.uni-frankfurt.de (Anselm Lingnau) Organization: University of Frankfurt/Main, Dept. of Mathematics In article <1992Oct10.010412.3448@waggen.twuug.com>, broberts@waggen.twuug.com (Bill Roberts) writes: > My most interesting in the reguard was when I deleted "/dev/null". Of > course it was soon recreated as a "regular file", then permission problems > started to show up. Years ago when I was working in the Graphics Workshop at Edinburgh University, we used to have a small UNIX machine for testing. The machine wasn't used too much, so nobody bothered to set up user accounts, and so everybody was running as root all the time. Now one of the chaps who used to come in was fond of reading fortunes (/usr/games/fortune having been removed from the University's real machines along with all the other games). Guess what happened when the machine said # fortune fortune: write error on /dev/null --- please empty the bit bucket Quite a lot of stuff wouldn't work after the chap was done with the machine for the day. You bet we put up proper accounts after that! Anselm ----------------------------------------------------------------------------- From: peter@NeoSoft.com (Peter da Silva) Organization: NeoSoft Communications Services -- (713) 684-5900 Well, we had one system on which you couldn't log in on the console for a while after rebooting, but it'd start working sometimes. What was happening was that the manufacturer had, for some idiot reason, hardcoded the names of the terminals they wanted to support into getty (this manufacturers own terminals, that I can understand, but also a handful of common types like adm3a) so getty could clear the screen properly (I guess hacking that into gettydefs was too obvious or something). If getty couldn't recognise the terminal type on the command line, it'd display a message on the console reading "Unknown terminal type pc100". We ignored this flamage, which was a pity. Cos that was the problem. It did this *before* opening the terminal, so if it happened to run between the time rc completed and the getty on the console started the console got attached to some random terminal somewhere, so when login attempted to open /dev/tty to prompt for a password it failed. Moral: always deal with error messages even when you *know* they're bogus. Moral: never cry wolf. ----------------------------------------------------------------------------- From: rickf@pmafire.inel.gov (Rick Furniss) Organization: WINCO Horror stories: Did this myself many years ago, and have come close to it since. Murphy's law #?? , preventive maintenence doesnt. try this one: /etc/dump /dev/rmt/0m /dev/dsk/0s1 Or: tar cvf /dev/root /dev/rmt0 Backups on unix can be one of the most dangerous commands used, and they are used to prevent rather than cause a problem. If any Unix utility were a candidate for a warning message, or error checking, this would be it. Just in case you didnt catch the HORROR above, the parameters are backworks causing a TOTAL wipe out of the root file systems. More systems have been wiped out by admins, than any hacker could do in a life time. ----------------------------------------------------------------------------- From: gfowler@javelin.sim.es.com (Gary Fowler) Organization: Evans & Sutherland Computer Corporation Once I was going to make a new file system using mkfs. The device I wanted to make it on was /dev/c0d1s8. The device name that I used, however, was /dev/c0d0s8 which held a very important application. I had always been a little annoyed by the 10 second wait that mkfs has before it actually makes the file system. I'm sure glad it waited that time though. I probably waited 9.9 seconds before I realized my mistake and hit that DEL key just in time. That was a near disaster avoided. Another time I wasn't so lucky. I was a very new SA, and I was trying to clean some junk out of a system. I was in /usr/bin when I noticed a sub directory that didn't belong there. A former SA had put it there. I did an ls on it and determined that it could be zapped. Forgetting that I was still in /usr/bin, I did an rm *. No 10 second idiot proofing with rm. Now if some one would only create an OS with a "Do what I mean, not what I say" feature. Gary "Experience is what allows you to recognize a mistake the second time you make it." Fowler ----------------------------------------------------------------------------- From: broadley@neurocog.lrdc.pitt.edu (Bill Broadley) Organization: University of Pittsburgh On a old decstation 3100 I was deleting last semesters users to try to dig up some disk space, I also deleted some test users at the same time. One user took longer then usual, so I hit control-c and tried ls. "ls: command not found" Turns out that the test user had / as the home directory and the remove user script in ultrix just happily blew away the whole disk. ftp, telnet, rcp, rsh, etc were all gone. Had to go to tapes, and had one LONG rebuild of X11R5. Fortunately it wasn't our primary system, and I'm only a student.... ----------------------------------------------------------------------------- From: hirai@cc.swarthmore.edu (Eiji Hirai) Message-ID: Sender: news@cc.swarthmore.edu (USENET News System) Nntp-Posting-Host: gingko Organization: Information Services, Swarthmore College, Swarthmore, PA, USA References: <2840@bsu-cs.bsu.edu> Date: Tue, 13 Oct 1992 16:00:28 GMT rik.harris@fcit.monash.edu.au writes: > I'll mount it in /tmp Though this may strike most sane sysadmins as bad practice, SunOS (3.4 or so - my memory is vague) shipped a command called "on". If you were logged on machine A and wanted to execute a command on machine B, you said "on B command", sort of like rsh. However, A would mount B's disks under some invokations of "on" and it would mount it in /tmp! Of course, lots of folks got bitten by this stupid command and it was taken out after a long delay by Sun. Anyone remember the details? I've blocked out my memory of pre-4.0 SunOS. Am I just hallucinating? ----------------------------------------------------------------------------- From: matthews@oberon.umd.edu (Mike Matthews) Organization: /etc/organization In article obi@gumby.ocs.com writes: >Now when I partition a disk I sit there with a calculator and make sure >all the numbers add up correctly (offsets, number of cylinders, number of >blocks, and so on). Heh heh, now that you mention that... We had just gotten a 1.2G disk drive for our Sun (which direly needed it) so we felt we'd repartition everything. All went well, except... on reboot, one of the partitions that was newly restored from backup got a fsck error. Fixed it, it rebooted, then another one got an error. fscked that one, rebooted it, and doggone it, the first error was back! We had a one cylinder overlap. Sheesh. At least Ultrix WARNS you of that. Mike Matthews, matthews@oberon.umd.edu (NeXTmail accepted) ----------------------------------------------------------------------------- From: mt00@eurotherm.co.uk (Martin Tomes) Organization: Eurotherm Limited We had something really wierd happen one day. I copied a file to /usr/local on someone elses machine and all seemed to be OK. A bit later the user of the machine noticed that the files and directories they were using on another disk partition were corrupted. There were 2 gigbyte files on a 650Mb disk - and lots of them with wierd names and permissions. At first I did not connect the two events. This disk had given trouble when the power failed a week before, so I fsck'ed it. Now I have run fsck more times than I can begin to imagine and seen plenty of errors, some needing 'manual intervention' but I had never seen anything like this before! It was spectacular. And what was more, when I ran it a second time things got worse. Then I tried to backup the /usr/local partition before restoring this corrupt data and lo, that was corrupt too. It turned out that our sysadmin had created the /usr/local disk partition in the wrong place on the disk and put it over the top of the alternate sectors partition. By writing to the /usr/local disk I had written all over the alts which were mapped into the users partition. Oh dear, what a mess. Solution, rebuild all the partitions so they don't overlap and restore, also buy the sysadmin a calculator. Moral, always do your sums on the /etc/partitions file very carefully before using mkpart. ----- UNIX-ADM USENET appended at 20:22:10 on 92/10/13 GMT (by USENET at ALMADEN) From: caa@Unify.Com (Chris A. Anderson) Organization: Unify Corporation, Sacramento, California Ok, here's one... At a company that I used to work for, the CEO's brother was the "system operator". It was his job to do backups, maintentance, etc. Problem was, he didn't have a clue about Unix. We were re- quired to go through him to do anything, though. Well, I was setting up a Plexus P-95 to be a news/mail/communications machine and needed to wipe the disks and install a new OS. El CEO requested that his brother do the in- stallation and disk partitioning. He had done this before, so I gave him the partition maps and let him at it. When he was done, everything seemed to be ok. Great, on with the install and set- up. Things went fine until I started compiling the news and mail software. All of a sudden, the machine paniced. I brought it back up and the root file system was amazingly corrupt. After rebuilding things, it all seemed to be fine -- diagnostics all ran fine, etc. So I started again -- this time keeping an eye on things. Sure enough, the root file system became corrupted again when the system started to load. This time I brought it down and checked everything. The problem? Swap space started at block zero and so did the root file system. ARRRGGGHHHHH!! Oh yes, the brother still works there. Chris ----------------------------------------------------------------------------- From: miles@Chaos.mcs.kent.edu (Roger Miles) Organization: Kent State University A year ago we moved to a brand spanking new building. All the equipment was moved by professional movers. The last piece of equipment I wanted moved was the computer (a Zilog s8000, 6ft. tall, with 3 disk drives, cartridge drive and reel tape drive all mounted in one cabinet. It must have weighed 250 to 300 lbs) because I wanted to keep an eye on the movers. Actually, I was hoping they'd drop it so I could get a new computer. Anyway, much to my surprize the movers said they would not move the computer because of the liability. One of my co-workers owned a Ford pickup so we hoisted it up and drove off with me riding in the back hanging on to the Zilog. It was the longest 15 minute drive I was ever on in my life. Roger Miles KSU ----------------------------------------------------------------------------- From: tjm@hrt213.brooks.af.mil (Tim Miller) Organization: AL/HRTI, Brooks AFB This one qulaified for Stupid Act of the Month: All this happened on my sparcII... I was making room on / because I needed to to test run something (which was using a tmp file in, of all places, /var/tmp. I could have recompiled the application to use more memory and/or /tmp, but I'm too lazy for that), so I figure "I'll just compress this, and this, and this..." One of those "this'" was vmunix. Well, of course the application crashes the machine, and stupid me had forgotten that I'd compressed vmunix, so the damn thing won't boot. checksum: Bad value or some such error. Took me most of the day to figure out just what I'd done to the dang thing. 8) Moral(s): 1) Never, ever, EVER play with vmunix. 2) Always keep a log of what you do to the root file system. ----------------------------------------------------------------------------- From: jarocki@dvorak.amd.com (John Jarocki) Organization: Advanced Micro Devices, Inc.; Austin, Texas In article ericw@hobbes.amd.com (Eric Wedaa) writes: > >The moral(s) of the story here: [Eric's "Guidebook to Being a Good Paranoid UNIX Sysadmin" Deleted] > >>>>Ericw >(Paranoia is a "Good Thing" when you can really muck things up!) >-- >Eric Wedaa - eric.wedaa@amd.com 3 Two more kinds of lies... >{ames apple uunet}!amd!ericw 3 Release Dates, and Benchmarks >Advanced Micro Devices, M/S 167 PO Box 3453 Sunnyvale, CA 94088-3453 >=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Eric, You left out an important one: - Never hand out directions on "how to" do some sysadmin task until the directions have been tested thoroughly. - Corollary: Just because it works one one flavor on *nix says nothing about the others. '-} - Corollary: This goes for changes to rc.local (and other such "vital" scripties. ----------------------------------------------------------------------------- From: bill@chaos.cs.umn.edu ( Hari Seldon ... psychohistorian ) Organization: University of Minnesota In <1992Oct13.014245.24930@ccu1.aukuni.ac.nz> russells@ccu1.aukuni.ac.nz (Russell Street) writes: >rca@Ingres.COM (Bob Arnold) writes: >> 9) It's a lot less painful to learn from someone else's experience >> than your own (that's what this thread is about, I guess :-) ) >With out trying to wander off the thread tooooo much ... In my >experience the best experiences to learn off are your own :) >I wonder how many stories we have got so far about "I will never >type rm -r /" as root. (And no I have not done that _yet_, but >the day will come :() after a real bad crash (tm) and having been an admin (on an rs/6000) for less than a month (honest it wasn't my fault, yea right stupid) we got to test our backup by doing: # cd / # rm -rf * ohhhhhhhh sh*t i hope those tapes are good ya know it's kinda funny (in a perverse way) to watch the system just slowly go away. bill pociengel ----------------------------------------------------------------------------- From: barrie@calvin.demon.co.uk (Barrie Spence) Organization: DataCAD Ltd, Hamilton, Scotland In article <1992Oct13.014245.24930@ccu1.aukuni.ac.nz> russells@ccu1.aukuni.ac.nz (Russell Street) writes: >rca@Ingres.COM (Bob Arnold) writes: >> 9) It's a lot less painful to learn from someone else's experience >> than your own (that's what this thread is about, I guess :-) ) > >With out trying to wander off the thread tooooo much ... In my >experience the best experiences to learn off are your own :) >I wonder how many stories we have got so far about "I will never >type rm -r /" as root. (And no I have not done that _yet_, but >the day will come :() > My mistake on SunOS (with OpenWindows) was to try and clean up all the '.*' directories in /tmp. Obviously "rm -rf /tmp/*" missed these, so I was very careful and made sure I was in /tmp and then executed "rm -rf ./.*". I will never do this again. If I am in any doubt as to how a wildcard will expand I will echo it first. Barrie ----------------------------------------------------------------------------- From: root@trebor.uucp (Bob Stockler) Organization: Bob Stockler rca@Ingres.COM (Bob Arnold) writes: >Morals: > 2) Don't do backups to floppies. Once, Tandy Xenix had the largest installed base of *NIX systems extant. My friend, mentor and guru Bob Snapp and I undertook to write a systematic backup set of shell scripts do what the *NIX programs then available would not do: make a reliable compressed Master Backup, and reliable compressed incremental backups (so 'cron' could do it) to available 8" floppy drives. We've never found that our programs failed. Now, on SCO *NIX systems we prefer CTAR. We've never found it to fail either. ----------------------------------------------------------------------------- From: JRowe@cen.ex.ac.uk (J.Rowe) Organization: Computer Unit. - University of Exeter. UK In article rik@nella15.cc.monash.edu.au (Rik Harris) writes: > I said to myself (being a Friday afternoon...see previous > post) "it's only temporary.../mnt is already being used...I'll mount > it in /tmp". So, I mounted on /tmp/a (or something). This was fine > for a few hours, but then the auto-cleanup script kicked in, and blew > away half of my source (the stuff over 2 weeks old). I didn't notice > this for a few days, though. After I figured out what had happened, > and restored the files (we _do_ have a good backup strategy), > everything was OK. If you're doing this using find always put -xdev in: find /tmp/ -xdev -fstype 4.2 -type f -atime +5 -exec rm {} \; This stops find from working its way down filesystems mounted under /tmp/. If you're using, say, perl you have to stat . and .. and see if they are mounted on the same device. The fstype 4.2 is pure paranoia. Needless to say, I once forgot to do this. All was well for some weeks until Convex's version of NQS decided to temporarily mount /mnt under /tmp... Interestingly, only two people noticed. Yes, the chief op. keeps good backups! Other triumphs: I created a list of a user's files that hadn't been accessed for three months and a perl script for him to delete them. Of course, it had to be tested, I mislaid a quote from a print statement... This did turn into a triumph, he only wanted a small fraction of them back so we saved 20 MB. I once deleted the only line from within an if.. then statement in rc.local, the sun refused to come up, and it was surprisingly difficult to come up single user with a writeable file system. AIX is a whole system of nightmares strung together. If you stray outside of the sort of setup IBM implicitly assume you have (all IBM kit, no non IBM hosts on the network, etc.) you're liable to end up in deep doodoo. One thing I would like all vendors to do (I know one or two do) is to give root the option of logging in using another shell. Am I the only one to have mangled a root shell? John Rowe ----------------------------------------------------------------------------- From: kochmar@sei.cmu.edu (John Kochmar) Organization: The Software Engineering Institute A long time ago, back when the Apollo 460 was around and I had just graduated from college, I had the good fortune of being one of two adminstrators in charge of making a cluster of 460's a part of our environment. One of the things I was tasked with was geting them onto our network. Well, I was young, I had the manuals, and a guy from Apollo tech support was there to help. How hard could it be, right? Well, we got out the manuals, configured the system (relying heavily on the defaults), and within 2 hours, we had that puppy on the network. Life was good. About 3 hours later, I get a phone call from a systems programmer / developer from CMU campus (the SEI is a part of CMU, and we are on their network.) He told me that if I didn't take the &%@*ing Apollo off the network, he was going to do hurtful things to me physically. Life was not so good. As it turned out, in default mode, the Apollo answered every address request it saw, even if it is not the machine the request was for. Kind of a "hey, I'm not who you are looking for, but I'm out here in case you decide you'd rather talk to me." Apollo considered this a feature, and they took advantage of it in their OS environment. However, one of the earlier versions of a heavily network dependant OS developed at CMU considered this a bug. The OS would issue a request, and expect only the machine it was looking for to answer it. Of course, it would assume that if it got an answer to its request, it must be the machine it expected to talk to. It didn't look at the address of the answer it got, so if it wasn't the correct machine, most of the time the OS would hang or panic. The outcome? Over about 3 hours time, more and more of campus was talking to our little 460, which had just enough muscle to keep up with the requests. By the time campus figured out what was going on, we had an Apollo merrily answering the network requests for hundreds of machines (the ones that were still up, that is.) This caused the part of campus who used the new OS going to hell in a bucket, one very busy Apollo 460, and one very warm ethernet. Well, we turned off the Apollo, configured it not to chat to all of campus before putting it back on the ethernet (this time, we did it while talking with campus, making sure we didn't cause the same problems we did the last time -- we didn't have a packet monitor at the time), and campus changed their OS to look at the request response before assuming it was the correct one. I also learned to think very carefully about default values before using them. John ----------------------------------------------------------------------------- From: djd@csg.cs.reading.ac.uk (David J Dawkins) Organization: University of Reading weave@bach.udel.edu (Ken Weaverling) writes: >A friend of mine called me up saying he no longer could log into his >system. I asked him what he had done recently, and found out that he >thought that all executable programs in /bin /usr/bin /etc and so on >should be owned by bin, since they were all binaries! So he had >chown'ed them all. Oh you bastards. I was hoping that a thread like this would never appear, because if it did, I knew I would have to confess. Oh well... About a year back, I was looking through /etc and found that a few system files had world write permission. Gasping with horror, I went to put it right with something like dipshit# chmod -r 664 /etc/* (I know, I know, goddamnit!.. now) Everything was OK for about two to three weeks, then the machine went down for some reason (other than the obvious). Well, I expect that you can imagine the result. The booting procedure was unable to run fsck, so barfed and mounted the file systems read-only, and bunged me into single-user mode. Dumb expression..gradual realisation..cold sweat. Of course, now I can't do a frigging chmod +x on anything because it's all read-only. In fact I can't run anything that isn't part of sh. Wedgerama. Hysteria time. Consider reformatting disks. All sorts of crap ideas. Headless chicken scene. Confession. "You did WHAT??!!" Much forehead slapping, solemn oaths and floor pacing. Luckily, we have a local MegaUnixGenius who, having sat puzzled for an hour or more, decided to boot from a cdrom and take things from there. He fixed it. My boss, totally amazed at the fix I'd got the system into, luckily saw the funny side of it. I didn't. Even though at that stage, I didn't know much about unix/suns/booting/admin, I did actually know enough to NOT use a command like the one above. Don't ask. Must be the drugs. BTW, if my future employer _is_ reading this (like they say he/she might), then I have certainly learned tonnes of stuff in the last year, especially having had to set up a complete Sun system, fix local problems, etc :-) Anyone else got a tale of SGS (Spontaneous Gross Stupidity) ? -dave "I'm much better now, honest.. no, really.. hey what's this button doooooooooOOOOOO..." ----------------------------------------------------------------------------- From: kelley@epg.nist.gov (Mike Kelley) Organization: NIST Sometimes you just can't win . . . We have a cluster of HP workstations and, once upon a time, were using 1/4-tape as the backup medium. This was very slow and cumbersome, as we were forever increasing the amount of disk space on our system, and we decided to purchase HP's optical jukebox to use both as large removable media and as the primary backup device. We had been experiencing occasional problems with the 1/4-inch tape backups, but HP's hardware service engineer convinced us that the problems were resolved. A complete backup was performed prior to installation (by the HP engineer) of the jukebox. Two unfortunate things happened. First, the problems on our backup tapes were due to intermittent hardware problems on the tape drive which were not discovered by the extensive diagnostics performed on the tape drive. Second, the engineer installed the jukebox with the same hardware SCSI address as our root file system. As you may have anticipated, the attempt to mediainit the first optical cartridge resulted in a rather ungraceful failure of the root file system. This was compounded by the fact that much of the data on the backup tapes was not recoverable. ----------------------------------------------------------------------------- From: ericw@hobbes.amd.com (Eric Wedaa) Organization: Advanced Micro Devices, Inc. The moral(s) of the story here: -NEVER use 'rm ', use rm -i ' instead. -Do backups more often than you go to church. -Read the backup media at least as often as you go to church. -Set up your prompt to do a `pwd` everytime you cd. -Always do a `cd .` before doing anything. -DOCUMENT all your changes to the system (We use a text file called /Changes) -Don't nuke stuff you are not sure about. -Do major changes to the system on Saturday morning so you will have all weekend to fix it. -Have a shadow watching you when you do anything major. -Don't do systems work on a Friday afternoon. (or any other time when you are tired and not paying attention.) >>>Ericw (Paranoia is a "Good Thing" when you can really muck things up!) ----------------------------------------------------------------------------- From: rob@wzv.win.tue.nl (Rob J. Nauta) Organization: None mfraioli@grebyn.com (Marc Fraioli) writes: >Well, here's a good one for you: > I was happily churning along developing something on a Sun workstation, >and was getting a number of annoying permission denieds from trying to >write into a directory heirarchy that I didn't own. Getting tired of >that, I decided to set the permissions on that subtree to 777 while I >was working, so I wouldn't have to worry about it. At my previous employer, the sysadmin would create new user accounts by hand by editing the passwd file, create a home dir, put some files in it, and chown '*' and '.*' to that new user. Thus, /home/machine was also chowned ('.*' also matches '..'). It was quite handy to see who was added last, but after a while i slipped him the hint to chown '.Ua-z~*' which works much better of course. But the stories told now are more folklore than real horror. Having read 2 Stephen Kings this weekend I beg everyone to tell more interesting stories, about demons, the system clock running backwards, old files reappearing etc ! Rob ----------------------------------------------------------------------------- From: alan@spuddy.uucp (Alan Saunders) Organization: Spuddy's Public Usenet Domain About inexperienced sysadmins .. One such had been on a Sun syasadmin course, and learned all about security. One of the topics was on file and group access. On his return, he decided to put what he had learned into practice, and changed the ownership of all files in /bin, /usr/bin to bin.bin! I was called in when no one could log in to the system (of course /bin/login needs to be setuid root!) Regards .. Alan ----------------------------------------------------------------------------- From: robjohn@ocdis01.UUCP (Contractor Bob Johnson) Organization: Tinker Air Force Base, Oklahoma >Arne Asplem (aras@multix.no) wrote: > I'm the program chair for a one day conference on Unix system > administration in Oslo in 3 weeks, including topics like network > management, system admininistration tools, integration, print/file-servers, > securitym, etc. > > I'm looking for actual horror stories of what have gone wrong because > of bad system administration, as an early morning wakeup. Management told us to email a security notice to every user on the our system (at that time, around 3000 users). A certain novice administrator on our system wanted to do it, so I instructed them to extract a list of users from /etc/passwd, write a simple shell loop to do the job, and throw it in the background. Here's what they wrote (bourne shell)... for USER in `cat user.list`; do mail $USER But the stories told now are more folklore than real horror. Having read > 2 Stephen Kings this weekend I beg everyone to tell more interesting > stories, about demons, the system clock running backwards, old files > reappearing etc ! I once had problems with files that mysteriously refused to stayed changed for very long. It was a PDP-11 Unix system that had crashed, and I brought it up single-user. I would change some file and it would stay changed for a minute or so but then revert to its earlier state (contents, protection mode, etc). What happened was that the write-protect switch on the disk drive had gotten bumped into the "on" position but the device driver failed to report any write errors. As long as the data stayed in kernel buffers the changes "took", but they would disappear once the buffers were reused and the system had to reread the disk. -greep ----------------------------------------------------------------------------- From: sam@bsu-cs.bsu.edu (B. Samuel Blanchard) Organization: Dept. of CS Ball State University Muncie IN #1 I never actually verified it but I think I deleted some of my bosses files as a very novice sysadmin. He found some things missing after I had a minor tangle with rm. When he ask I said I had run into a problem and he smiled and let it go. Sorry Raul! #2 I had a boss continue to reboot a dying system in an attempt to print out material for his conference presentation. He was not interested in waiting until I worked on the system; if he couldn't get it working, he assumed I couldn't. I quit :-( Then he quit :-) Then I spent a weeking fixing the system. :-0 <--words edited Some thing have improved there they tell me. Disclaimer: This is purely my interpretation and not intended to offend. It was my pre-assumption that you didn't read this group. #3 Recently had someone recover an old full backup over a running system. A manager 2 levels up noticed that our automatic backup, written by his staff, was failing far too often. Even worse, it did not always report errors. Since I was gone, he felt free to assign a manual backup to another group. The guy doing the "backup" called a member of his group at 8pm, that person finally called me at some un-goddly hour in the morning (I was glad he called!). The best part was the end result. We now do backups in our group. Don't you love how progress slaps you awake some times. ----------------------------------------------------------------------------- From: cjc@ulysses.att.com (Chris Calabrese) Organization: AT&T Bell Labs, Murray Hill, NJ, USA In article <7515@blue.cis.pitt.edu.UUCP> broadley@neurocog.lrdc.pitt.edu writes: >On a old decstation 3100 I was deleting last semesters users to try to >dig up some disk space, I also deleted some test users at the same time. > >One user took longer then usual, so I hit control-c and tried ls. >"ls: command not found" > >Turns out that the test user had / as the home directory and the remove >user script in ultrix just happily blew away the whole disk. >U...~ Reminds me of a bit of local folk-lore (this happened before I was in the admin group)... We have a home-grown admin system that controls accounts on all of our machines. It has a remove user operation that removes the user from all machines at the same time in the middle of the night. Well, one night, the thing goes off and tries to remove a user with the home directory '/'. All the machines went down, with varying ammounts of stuff missing (depending on how soon the script, rm, find, and other importing things were clobbered). Nobody knew what what was going on! The systems were restored from backup, and things seemed to be going OK, until the next night when the remove-user script was fired off by cron again. This time, Corporate Security was called in, and the admin group's supervisor was called back from his vacation (I think there's something in there about a helicopter picking the guy up from a rafting trip in the Grand Canyon). By chance, somebody checked the cron scripts, and all was well for the next night... ----------------------------------------------------------------------------- From: sam@bsu-cs.bsu.edu (B. Samuel Blanchard) Organization: Dept. of CS Ball State University Muncie IN Oh yea, I recalled 2 more kill -1 1 on an Altos SV box is not good. I pulled this one trying to show off. No more gettys appeared when uses logged off. When I went to the console, I calmly typed 0 to the Run Level request prompt. 2 would have been nice? It was my first SystemV like box, and it seemed to have such nice berkley commands. a control-s on a Sequent S27 console can cause processes to hang waiting to write to the console. Unfortunatly, su is one such process. No real problem since I don't blindly reboot on request ;-) ----------------------------------------------------------------------------- From: pete@tecc.co.uk (Pete Bentley) Organization: T.E.C.C. Ltd, London, England David J Dawkins (djd@csg.cs.reading.ac.uk) wrote: : About a year back, I was looking through /etc and found that a few : system files had world write permission. Gasping with horror, I went : to put it right with something like : : dipshit# chmod -r 664 /etc/* : A similar thing happened at a place a used to work 3 or 4 years back. The guys next door had just got a Sun 3/360 (or some such) to host a VME-bus image processing system - none of them knew much (or cared much) about Un*x and so early on a student on loan to them got a space in the wrong place and did pillock# chmod -r -x ~ /* with the same results (system in single user, refusing to run any commands or go multi-user). As it happened a) This was a government establishment, and so the order for the QIC tapes for backups had not yet been approved, hence no backups... b) The install script for the kernel drivers for the image processing stuff had not worked 'out of the box', and so the company had sent an engineer down to install it. I hadn't been around when he came and built their drivers, and they hadn't a clue what he had done. So, there was no way to rebuild the drivers without another engineer call and because of (a) there were no backups of the driver...Anyway, a complete reload was therefore out of the question. These were the days before SunOS on CD-ROM. In the end I managed to get the thing up by booting from tape, installing the miniroot into the swap partition and booting from that. This gave me a working tar and a working mount, but no chmod. Also no mt command. Also at this time very little of my Un*x experience was on Suns, so I had no idea of the layout of the distribution tape. Various experiments with dd and the non-rewinding tape device eventually found the file on the tape with a chmod I could extract. chmod +x /etc/* /bin/* /usr/bin/* on the system's existing disk was enough to make it bootable. After that I sat the student down with a SunOS manual and let him figure out the mess and correct the permissions that had been todged all over the system... Pete. ----------------------------------------------------------------------------- From: rca@Ingres.COM (Bob Arnold) Organization: Ask Computer Systems Inc., Ingres Division, Alameda CA 94501 In article <1992Oct12.233524.13463@pony.Ingres.COM> I wrote: >I was brave and bold, not to mention boneheaded, and formatted the user disk. > > U rest of story deleted ... Bob ~ > >Morals: > 1) The "man" pages don't tell you everything you need to know. > 2) Don't do backups to floppies. > 3) Test your backups to make sure they are readable. > 4) Handle the format program (and anything else that writes directly > to disk devices) like nitroglycerine. > 5) Strenuously avoid systems with inadequate backup and restore > programs wherever possible (thank goodness for "restore" with > an "e"!). > 6) If you've never done sysadmin work before, take a formal > training class. Just thought of a few more related morals (managers pay attention now): 7) You get what you pay for. 8) There's no substutite for experience. 9) It's a lot less painful to learn from someone else's experience than your own (that's what this thread is about, I guess :-) ) Part of the story I should tell here. My employer had been looking for a way to cut costs. I was 15% cheaper than their previous sysadmin so they let him go and hired me. It wasn't as nasty as it sounds, since they kept him on as a consultant at 4 hours a week and he ended up with a better job too (so did I). Everyone benefited in the end. I leaned heavily on his consulting, which was great. He was older and wiser, and probably had his own horror stories to tell. After this one, so did I! Bob ----------------------------------------------------------------------------- From: rca@Ingres.COM (Bob Arnold) Organization: Ask Computer Systems Inc., Ingres Division, Alameda CA 94501 Many moons ago, in my first sysadmin job, learning via "on-the-job training", I was in charge of a UNIX box who's user disk developed a bad block. (Maybe you can see it already ...) The "format" man page seemed to indicate that it could repair bad blocks. (Can you see it now?) I read the man page very carefully. Nowhere did it indicate any kind of destructive behavior. I was brave and bold, not to mention boneheaded, and formatted the user disk. Heh. The good news: 1) The bad block was gone. 2) I was about to learn a lot real fast :-) The bad news: 1) The user data was gone too. 2) The users weren't happy, to say the least. Having recently made a full backup of the disk, I knew I was in for a miserable all day restore. Why all day? It took 8 hours to dump that disk to 40 floppies. And I had incrementals (levels 1, 2, 3, 4, and 5, which were another sign of my novice state) to layer on top of the full. Only it got worse. The floppy drive had intermittent problems reading some of the floppies. So I had to go back and retry to get the files which were missed on the first attempt. This was also a port of Version 7 UNIX (like I said, this was many moons ago). It had a program called "restor", primordial ancestor of BSD's "restore". If you used the "x" option to extract selected files (the ones missed on earlier attempts), "restor" would use the *inode number* as the name of the extracted files. You had to move the extracted files to their correct locations yourself (the man page said to write a shellscript to do this :-(). I didn't know much about shell scripts at the time, but I learned a lot more that week. Yes, it took me a full week, including the weekend, maybe 120 hours or more, to get what I could (probably 95% of the data) off the backups. And there were a few ownership and permissions problems to be cleaned up after that. Once burned twice shy. This is the only truly catastrophic mistake I've ever made as a sysadmin, I'm glad to be able to say. I kept a copy of my memo to the users after I had done what I could. Reading it over now is sobering indeed! I also kept my extensive notes on the restore process - thank goodness I've never had to use them since. Morals: 1) The "man" pages don't tell you everything you need to know. 2) Don't do backups to floppies. 3) Test your backups to make sure they are readable. 4) Handle the format program (and anything else that writes directly to disk devices) like nitroglycerine. 5) Strenuously avoid systems with inadequate backup and restore programs wherever possible (thank goodness for "restore" with an "e"!). 6) If you've never done sysadmin work before, take a formal training class. Well, I haven't thought about that one in a while! I can laugh about it now .... Bob ----------------------------------------------------------------------------- From: jimh@pacdata.uucp (Jim Harkins) Organization: Pacific Data Products A friend of mine admins an RS6000 for a state college. The weekend before the fall semester started the Powers That Be decided to physically move the system to a different room. She stayed late friday night, moved the machine, and then it wouldn't boot. I was in Sunday afternoon looking at it, wouldn't boot for nothing. Monday morning, first day of classes, an IBM rep comes in and reformats the hard disk without telling her. Turns out this was the machine all the professors were doing their class plans on. So not only couldn't they have them printed out, but when school started monday morning the teachers discovered they had lost all the work they'd done in the week before school started. Seems she never did backups because the teachers always bitched about how slow the system was when she did, and she hadn't learned about cron yet (I told her about that one). In her defense, she'd only been using the RS6000 for less than a month before this happened. She didn't know UNIX. She hadn't had any training. She still had her regular job to do. To make things worse, when she called me monday night she was in tears as she told me how she had to personally visit all the professors and tell them their work was gone. I blurted out "Stupid of you not to make backups". Here she is looking for a shoulder to cry on and I go and tell her the same thing everybody from the department chair on down to the janitor had been saying. Oops. The moral? If you appoint someone to admin your machine you better be willing to train them. If they've never had a hard disk crash on them you might want to ensure they understand hardware does stuff like that. I also found out she was unplugging and plugging cables all over the place without powering down the system. Her hardware knowledge was essentially "this thing goes into the wall, then the lights blink". jim ----------------------------------------------------------------------------- From: russells@ccu1.aukuni.ac.nz (Russell Street) Organization: University of Auckland, New Zealand. Not quite a reall _horror_ story but ... I once had "gnu-emacs" aliased to 'em' (and 'emacs' etc) One day I wanted to edit the start up file and mistyped # rm /etc/rc.local instead of the obvious. *Fortunately* I had just finished a backup and was now finding out the joys of tar and it's love of path names. U./etc/rc.local and /etc/rc.local and etc/rc.local) are *not* the same for tar and TK-50s take a *long* time search for non-existant files :(~ Of course the BREAK (Ctrl-P) key on a VAX and an Ultrix manual and a certain /etc/ttys line are just a horror story waiting to happen! Especially when the VAX and manuals are in a unsupervised place :) ----------------------------------------------------------------------------- From: obi@gumby.ocs.com (Obi Thomas) Organization: Online Computer Systems, Inc. This isn't nearly as bad as some of the stories in this thread, but... I once mistakenly partitioned my Sun's boot disk so that the swap partition overlapped the usr partition. The machine ran fine for a long time (many months), presumably because the swap space was always nearly empty. Then, one day there was a memory parity error and the system crash dumped at the *end* of the swap partition. What should have been a simple reboot after the crash dump turned into a long and painful re-install of the entire system (Suns cannot boot without a /usr partition). Now when I partition a disk I sit there with a calculator and make sure all the numbers add up correctly (offsets, number of cylinders, number of blocks, and so on). ----------------------------------------------------------------------------- From: dp@world.std.com (Jeff DelPapa) Organization: The World Public Access UNIX, Brookline, MA In article obi@gumby.ocs.com writes: >This isn't nearly as bad as some of the stories in this thread, but... > >I once mistakenly partitioned my Sun's boot disk so that the swap >partition overlapped the usr partition. The machine ran fine for a long >time (many months), presumably because the swap space was always nearly >empty. I remember a similar thing once - on a symbolics machine, a customer declared a file in the FEP filesystem as a paging file, and as part of the file system (it was one way to solve their disk space crunch) It was caught before damage was done - we weren't sure if it was because they hadn't done anything real yet, or simply the machine knew not to mess with the IRS (the customer). ----------------------------------------------------------------------------- From: rik@nella15.cc.monash.edu.au (Rik Harris) Organization: Monash University, Melb., Australia. Sometimes it takes a few tries to get it through the tired brain... Most of our disks reside on a single, high-powered server. We decided this probably wasn't too good an idea, and put a new disk on one of the workstations (particularly since the w/s has a faster transfer rate than the server does!). It's still really useful to be able to use all disks from the one machine, so I mounted the w/s disk on the server. I said to myself (being a Friday afternoon...see previous post) "it's only temporary.../mnt is already being used...I'll mount it in /tmp". So, I mounted on /tmp/a (or something). This was fine for a few hours, but then the auto-cleanup script kicked in, and blew away half of my source (the stuff over 2 weeks old). I didn't notice this for a few days, though. After I figured out what had happened, and restored the files (we _do_ have a good backup strategy), everything was OK. Until a few months later. We were trying to convince a sysadmin from another site that he shouldn't NFS export his disks rw,root to everyone, so I mounted the disk to put a few suid root programs in his home directory to convince him. Well, it's only a temporary mount, so.... You guessed it, another Friday afternoon. I did a umount /tmp/b, and forgot about it. I noticed this one about halfway through the next day. (NFS over a couple of 64k links is pretty slow). The disk had not unmounted because it was busy...busy with two find scripts, happily checking for suid programs, and deleting anything over a week old. A df on the filesystem later showed about 12% full :-( Sorry Craig. Now, I create /mnt1, /mnt2, /mnt3.... :-) Remember....Friday afternoons are BAD news. rik. ----------------------------------------------------------------------------- From: ranck@joesbar.cc.vt.edu (Wm. L. Ranck) Hello folks, Well, after reading some of the stories in this thread I guess I can tell mine. I got an RS/6000 mod. 220 for my office about 6 months ago. The OS was preloaded so I had little chance to learn that process. Being used to a full-screen editor I was not happy with vi so I read in the manual that INED (IBM's editor for AIX) was full-screen and I logged in as root and installed it. I immediately started to play with the new editor and somehow found a series of keys that told the editor to delete the current directory. To this day I don't know what that sequence of keys was, but I was unfortunately in the /etc directory when I found it, and I got a prompt that said "do you want to remove this?" and I thought i was just removing the file I had been playing with but instead I removed /etc! I got the chance to learn how to install AIX from scratch. I did reinstall INED even though I was a little gun-shy but I made sure that whenever I used it from then on I was *not* root. I have since decided that EMACS may be a better choice. ----------------------------------------------------------------------------- From: stehman%citron.cs.clemson.edu@hubcap.clemson.edu (Jeff Stehman) Organization: Clemson University From article <3965@wzv.win.tue.nl>, by rob@wzv.win.tue.nl (Rob J. Nauta): > > But the stories told now are more folklore than real horror. Having read > 2 Stephen Kings this weekend I beg everyone to tell more interesting > stories, about demons, the system clock running backwards, old files > reappearing etc ! Hmmm. Maybe this is a little closer to what you're looking for... Many years ago a tiny little college in the middle of nowhere purchased an NCR tower, then a newfangled contraption. A half-dozen of us were using it for an assembly class. The prof should have made his warnings about TRAP a little more clear. One student runs his program and it suddenly begans spawning processes, rapidly filling the machine. The prof came in, amused, logged on as superuser, and killed a process. Another process was immediately spawned. The prof tried again. He was ignored. He was also no longer amused. After several minutes he gave up and turned off the box. The tower didn't even flinch. He pulled the plug. Nothing. He ripped the back off the box and dug around. Finally he found the fuse and pulled it, killing the machine. Some of us later claimed we heard laughter as it went down. (Many times since then I have wished other computers came with a backup battery as standard issue.) ----------------------------------------------------------------------------- From: grover@ccai.clv.oh.us (grover davidson) Organization: CCAI Several months ago here, we were reoganizing our disk space on an RS/6000 with AIX 3.1. I have done this many time before, but for some reason, I was rushing through expanding a file system. Instead of entering the new file system size where it belongs, I entered it into the mount point. It also turns out that I was attached 2 levels down in the file system. Since the size was entered as a number ('234567') and was INTERPRETED as a mount point directory, the result was a circular hard link that basicly left the file system unusable. IBM was not able to help, and we had done quite a bit of work that day, we had to somehow recover some of the stuff. We ended up doing a dd of the raw volume, and the read it back in a couple MB at a time and extracted the pieces that we needed for the mess. The other day while reading Stevens new book, "Advanced Programming in the UNIX Environment", he stated that he had done the exact same thing durring the preparation of his book. At least I am not alone..... ----------------------------------------------------------------------------- From: dvsc-a@minster.york.ac.uk Organization: Department of Computer Science, University of York, England I remember my first (and only, so far) major mistake in unix admin: I was changing the UIDs of a few users on one of our major servers, due to a clash with some machines newly connected to the net. Fine, edit /etc/passwd then chown all their files to the new UID. So, rather than just assume that all files owned by "fred" live in /home/machine/fred I did this: machine# find / -user old_uid -exec chown username {} \; This was fine... except it was late at night and I was tired, and in a hurry to get home. I had six of these commands to type, and as they would take a long time I'd just let them run in the background over night..... So, you come in the next morning and a user compains... I can't login to the 4/490 - it says "/bin/login: setgid: not owner". Okay.... naive user problem no? rlogin machine -l root /bin/login: setgid: not owner machine console login: root /bin/login: setgid: not owner Okay - I REALLY can't get in... lets reboot single user and see whats on... this worked. /bin/login is owned (and setuid to) one of the users whos UID I changed the previous day... infact ALL FILES in the ENTIRE filesystem are owned by this user..problem! We `only' lost about 200 man hours through my little typing mistake: the moral of the story.. beware anything recursive when logged in as root! find / -exec chown user {} \; Oh dear... Dave ----------------------------------------------------------------------------- From: mba@controls.ccd.harris.com (Belinda Asbell) Organization: Harris Controls In article , JRowe@cen.ex.ac.uk (J.Rowe) writes: 3> One thing I would like all vendors to do (I know one or two do) is 3> to give root the option of logging in using another shell. Am I the 3> only one to have mangled a root shell? 3> 3> John Rowe 3> Dept. Physics 3> Exeter University 3> UK. Probably not. I learned the hard way to be careful if messing with /etc/passwd. One day, for some reason, I couldn't login as root (pretty scary, since I knew the root passwd and hadn't changed it). Turned out that somehow I'd blitzed the first letter of /etc/passwd somehow (vi does bizarre things sometimes). So I logged in as 'oot' and fixed it. NEVER do a "chmod -R u-s .", especially not in /usr.... I think that "mount -o" or something similar will mount a filesystem read-write if it's come up in singleuser mode and is mounted read-only..... Just my tuppence.... ----------------------------------------------------------------------------- From: joslin_paul@ae.ge.com Organization: GE Aircraft Engines cjc@ulysses.att.com (Chris Calabrese) writes: >We have a home-grown admin system that controls accounts on all of our >machines. It has a remove user operation that removes the user from >all machines at the same time in the middle of the night. >Well, one night, the thing goes off and tries to remove a user with >the home directory '/'. All the machines went down, with varying >ammounts of stuff missing (depending on how soon the script, rm, find, >and other importing things were clobbered). >Nobody knew what what was going on! The systems were restored from >backup, and things seemed to be going OK, until the next night when >the remove-user script was fired off by cron again. True confession time: Cron is a great way to hide your flubs. I installed the COPS security package on a system, then set up cron to recheck the system once a month. No problem, right? Except that I had configured COPS to put the reports in /. As a security measure, COPS chmods its directory to u-rwx,w-rwx so that only the COPS owner can read the reports. The chronology was 1) Run cops. Add cops entry to root's crontab. Later that day, notice that / was 600; change it back. 2) 30 days later: get calls from users - can't log in, "No shell" error messages. Find / is 600; change it. Vaguely remember that this happened once before. The machine was a sandbox, so almost anything could have changed /. 3) 30 days later: get calls from users - can't log in, "No shell" error messages. Find / is 600; change it. Vaguely remember that this happened once before. Happen to think "cron"; notice that the only cron activity for root last night was COPS. Read COPS source and discover problem. Moral: RTFM. Keep logs, so that you can notice patterns in your data. Don't do anything as root that you can do as a mortal. ----------------------------------------------------------------------------- From: root@rulcvx.LeidenUniv.nl (root) Organization: CRI, institute for telecommunication and computerservices. In article <64@ocdis01.UUCP> robjohn@ocdis01.UUCP (Contractor Bob Johnson) writes: >Another horror story (mine this time)... >Cleaning out an old directory, I did 'rm *', then noticed several files >that began with dot (.profile, etc) still there. So, in a fit of obtuse >brilliance, I typed... > rm -rf .* & Well, waddya know... Some half hour ago, coming back from root (I was installing m4 on our system) UShit, all my neato emacs tricks won't work. Damn, damn, damn kill, kill, KILL~ to my own userid, I got this little message: "Can't find home directory /mnt0/crissl." and an other: "Can't lstat .". UGrrrrr, *S and *Q haven't been remapped...~ Guess what happened, not an hour ago... A collegue of mine was emptying some directories of computer-course accounts. As I did a "ps -t" on his tty, what did I see? "rm -rf .*" Well, I'm not alone, he got sixteen other homedirectories as well. And guess what filesystems we don't make incremental backups of... And why not? Beats me... I haven't killed him yet, he first has to restore the lot. And for those "touch \-i" fans out there: you wouldn't have been protected... Boy, am I MAD. :-) (Bitten by the bug I, too, once released.) Stefan "where can I find a well-equipped torture chamber" Linnemann ----------------------------------------------------------------------------- From: hillig@U.Chem.LSA.UMich.EDU (Kurt Hillig) Organization: Department of Chemistry, University of Michigan, Ann Arbor Just so nobody get the impression that you can only screw up U**X systems.... Several years ago I was sysadmin for the department's VAX/VMS system. One day, trying to free up some space on the system disk, I noticed there were a bunch of files like COBRTL.EXE, BASRTL.EXE etc. - i.e. the Cobol, Basic, etc. run-time libraries. Since the only language used was Fortran, I nuked them. Three weeks later, a visiting professor came over from Greece for a few weeks, mostly to do some calculations on the VAX. He got in on a Friday morning, and started work that afternoon. About 7 PM I got a call at home - he'd accidentally bumped the reset switch (on the VAX 3200, it was just at knee height!) and it wouldn't reboot. I went back in and took a look, and the reason it wouldn't come up was that the run-time libraries were missing. I ended up booting stand-alone backup from tape, dumping another data disk to tape, restoring an old system from tape, copying the RTL's, then restoring the data disk from tape again - all with TK50's. Took me until 3 AM. ----------------------------------------------------------------------------- From: kevin@sherman.pas.rochester.edu (kevin mcfadden) Organization: University of Rochester Me and my co-system admin were in the process of repartioning a drive so that we could allocate more space for incoming mail. We had just finished backing up our Data directory from which we were going to take 10MB from. Next step was to to actually repartition it which includes formating. Anyway, it comes time to give a device name and we do a df to see which one. To make a short story long, there was a /dev/sd2g and a /dev/sd3g, one which was 300MB of stuff we could delete and the other was 600MB of applications. We confused the the two and accidently formatted the 600 MB of applications, which of course had been backed up......a month ago. It could have been worse. BUT WAIT!!! It did. Turns out it took 3 or 4 tries to get the partition size correct (what the hell is it with telling it how long it is in hex or whatever?). It was at this point where I started to cover my eyes and wander around the building because we only found out the partition didn't work after spending 3 hours restoring the applications. 4 * 3 = 12 hours to repartition! ----------------------------------------------------------------------------- From: johnd@cortex.physiol.su.oz.au (John Dodson) Organization: Department of Physiology, University of Sydney, NSW, Australia Some years ago when we went from Version 7 Unix on a PDP11 to a flavour of BSD on a Vax, I was working on the Vax in my home directory & came across a file that I had no permission on (I'd created it as root) so the following ensued... $ /bin/su - Password: # chown -R me * mmmmm this seems to be taking a long time ! kill. # ls -l the result was that I was in / after the su ! (good old V7 su used to leave you in the current directory ;-) It took me quite a while to restore all the right ownerships to /bin /etc & /dev (especially the suid/sgid files) I'd managed to kill it before it got off the root filesystem. not quite rm -fr / but... ----------------------------------------------------------------------------- From: jcm@coombs.anu.edu.au (J. McPherson) Organization: Australian National University A few months ago in comp.sys.hp, someone posted about their repairs to an HP 7x0, after a new sysadmin had just started work. They {the new person} had been looking throught the file system to try to make some space, saw /dev and the mainly 0 length files therein. Next command was "rm -f /dev/*" and they wondered why they couldn't login ;) I think the result was that the new person was sent on a sysamin's course a.s.a.p. ;) JC ----------------------------------------------------------------------------- From: pinard@IRO.UMontreal.CA (Francois Pinard) Organization: Universite' de Montre'al Many things happened in those many years I've been with computers. The most horrorful story I've seen is not UNIX related, but it is certainly worth a tale. Here it goes. This big (:-) CDC 6600 system was bootable from tape drive 0, using these 12 inches wheels containing 1/2" tape. The *whole* system was reloaded anew from the tape each time we restarted the machine, because there was no permanent file system yet, the disks were not meant to retain files through computer restarts (unbelievable today, I know :-). The deadstart tapes (as they were called) were quite valuable, and we were keeping at least a dozen backups of those, going back maybe one or two years in development. The problem was that the two vacuum capstans which were driving the tape 0, near the magnetic heads, were not perfectly synchronized, due to an hardware misadjustment. So they were stretching the tape while they were reading it, wearing it in a way invisible to the eye, but nevertheless making the tape irrecoverable. Besides that, everything was looking normal in the tape physical and electrical operations. Of course, nobody knew about this problem when it suddenly appeared. All this happened while all the system administration team went into vacation at the same time. Not being a traveler, I just stayed available `on call'. The knowledgeable operators were able solve many situations, and being kind guys for me (I was for them :-), they would not disturb me just for a non-working deadstart tape. Further, they had a full list of all deadstart backup tapes. So, they first tried (and destroyed) half a dozen backups before turning the machine to the hardware guys, whom destroyed themselves a few more. The technicians had their own systems for diagnostics, all bootable from tape drive 0, of course. They had far less backups to we did. They destroyed almost them all before calling me in. Once told what happened, my only suggestion was to alter the deadstart sequence so to become able to boot from another tape drive. Strangely enough, nobody thought about it yet. In these old times, software guys were always suspecting hardware, and vice versa :-). Happily enough, the few tapes left started, both for production and for the technicians. Tape drive 0 being quite suspectable, the technicians finally discovered the problem and repaired it. My only job left was to upgrade the system from almost one year back, before turning it to operations. This was at the time, now seemingly lost, when system teams were heavily modifying their operating system sources. This was also the time when everything not on big tapes was all on punched Hollerith cards, the only interactive device being the system console. It took me many days, alone, having the machine in standalone mode. The crowd of users stopped regularily in the windows of the computer room, taking bets, as they were used to do, on how fast I will get the machine back up (I got some of my supporters loosing their money, this time :-). This was quite hard work for me, done under high pressure. When the remainder of the staff returned from trip, and when I told them the whole tale, we decided to never synchronize our holidays again. ----------------------------------------------------------------------------- From: grant@unisys.co.nz (Grant McLean) Organization: Unisys New Zealand One of my customers (who shall remain nameless) was having a problem with insufficient swap space. I recommended that he back up the system, boot off the OS tape, repartition the disk, remake the filesystems and restore the data (any idiot could do this, right? :-) ). I also suggested that if he wasn't confident of achieving all this, we could provide a skilled person for a modest fee. Of course he was fully confident so I left him to it. Next day I get a call from the guy to say he'd been there all night and he'd had all sorts of funny messages when restoring from tape. Eventually we tracked his problem down to the backup script he'd been using. It was a simple one liner: find / -print 3 cpio -oc 3 dd -obs=100k of=/dev/rmt0 2>/dev/null This was a problem because: 1) His system had two 300MB drives 2) He only had a 150MB tape drive 3) The same script was being run every night by a cron job 4) All his backups were created by this script (In case you haven't worked it out, the dd is to speed up writes to tape but it has the unfortunate side effect that CPIO never finds out about the end of tape. Because the errors were going to the bit bucket, they never knew their backups were incomplete until they came to restore from them). I would have loved to be a fly on the wall when he explained to his boss that the data was gone and there was no way of getting it back. I haven't heard from the guy since then. Hmmm ... Grant ----------------------------------------------------------------------------- From: adb@geac.com (Anthony DeBoer) Organization: Geac Computer Corporation In article <1992Oct10.010412.3448@waggen.twuug.com> broberts@waggen.twuug.com (Bill Roberts) writes: >My most interesting in the reguard was when I deleted "/dev/null". Of >course it was soon recreated as a "regular file", then permission problems >started to show up. I was once called in to save a system where most things worked, but the main application package being used on it hung the moment you entered it (leaving the system more than a little useless for getting things done). I poked around for awhile, verified that the application's files were all present, undamaged, and had the right permissions. The folks who normally used the machine had also discovered that all was well if root tried to run it. But nothing was visibly wrong anywhere. So, being a bit hungry by then, I took a break for supper, and about halfway through, the little voice at the back of my head that sometimes helps me said, "/dev/tty". Sure enough, somebody had chmod'ded it to 0644, and the application directed (or tried to direct, in this case) all its I/O through it rather than just using stdin/stdout like a sane normal process. ----------------------------------------------------------------------------- From: nagappa@menudo.uh.edu (Chaitanya Nagappa) Organization: University of Houston The following article is posted by a friend from my account: Chai Nagappa =================================================================== Hi, This is Ravi. Needed to add just a couple of stories from all the wierd stuff that have happenned. So, are these tales for around a campfire on Halloween? At one time, there were three of us working on a unique SVR3.2 motorola based machine, on a R&D project. I took care of all the SysAdmin tasks, I had a back up administrator, and the third person had been stuck into my group (company politics). The group project files were in /user and the individial ones in /user2. We had managed to get backup from the operations department for /user only (not even /; security paranoia?). Anyway, I had another scsi hard disk that I used for making a disk copy of the primary scsi hard disk every Friday. This disk was connected, but not mounted, so that I could do the disk backup from my desk when I wanted to. This machine used to sometimes get a scsi error such that you could not log in, but the processes already running on the machine were not affected. If were logged in the console, you just powered off the machine for a few minutes and rebooted it. Around holidays time the other Admin was off in a long vacation. I had taken Monday off, and headed off for a four day weekend. The machine does the same blurp. The third person decides the power off the machine & turn it back on immediately. It does not come up properly. She decides to reinstall the machine using the installation tape that I had unfortunately left in the open. Reformats the hard disk, installs the base system, and is stuck at that point when I come back in on Tuesday. I almost blow a blood vessel but try to keep calm 'cause I had made a disk copy about 10 days before (too anxious to get on my holiday the previous week). Try to mount the disk... hit vaccuum. Try using dd to look at the disk... Seemed to be a large /dev/null :-? When the lady decided to reinstall the system, it asked her what scsi disks she wanted to reformat, and she said "y" for both 0 & 1!! All my sample/trial&error work for a year had bitten the dust. My only (small) consolation was that I was not the only one affected. Story 2. Live 24 hour online system. Does backup over the ethernet to a SCSI tape. Unfortunately, no SCSI on this system to recover if root/ethernet dies. This was a Compaq Systempro running SCO Unix. Slated a downtime of 4-6am. I thought that it will take me only 30 minutes, as I had installed a similar (Adaptec) SCSI board on a similiar hardware on SCO. Only difference was that this machine was running MPX (multiprocess extension) and you had to deinstall it, install the SCSI, and then reinstall MPX (proper procedure). I had made all my slot/IRQ charts the previous day, and so got busy removing MPX. Then said "mkdev tape", go through the IDs, and am almost at home base. Then... "link kit not installed, use floppy X1" when I tried to remake the kernel. For some reason, when I removed the multiprocessor extension, the single processor files were not moved to their right location. And if I reinstalled the single, all my changes would be lost. Finally, restored the OS (from backup) on the remote machine, and then rcp-ed them over to bring back the MPX version. Unfortunately, rcp does not maintain the date/ permissions, etc. Got a limpimg version of the machine back on-line about 45 minutes after its slated time, and spent the rest of the day fixing vagrant files. The next week, I moved the online programs to another machine (a headache), and reinstalled this machine from scratch. Ok, that should be enough horror. Please send any replies to "ravi@usv.com" instead of this account. Thanks, --Ravi Ramachandran ----------------------------------------------------------------------------- From: grog@lemis.uucp (Greg Lehey) Organization: LEMIS, W-6324 Feldatal, Germany In article <16055@umd5.umd.edu> matthews@oberon.umd.edu (Mike Matthews) writes: >The moral? *NEVER* move something important. Copy, VERIFY, and THEN delete. Something like this bit me just yesterday. I'm currently trying to work out how ISC Unix/386 handles COFF files, and discovered the /shlib directory, which I suspected wasn't really used (*wrong*). So, to try it out, I did: + root adagio:/ 819 -> mv shlib slob + root adagio:/ 820 -> xterm + /usr/bin/X11/xterm: Can not access a needed shared library So far, so good. So, put it back: + root adagio:/ 821 -> mv slob shlib + /bin/mv: Can not access a needed shared library Oops! So, tried it from a different system, but didn't have permission, so: + root adagio:/ 822 -> chmod 777 slob + /bin/chmod: Can not access a needed shared library OK, so let's just cp them across. + root adagio:/ 823 -> cd slob + root adagio:/slob 824 -> mkdir /shlib + /bin/mkdir: Can not access a needed shared library + root adagio:/slob 825 -> Then I wrote a program which just did a link(2) of the directories. Yes, gcc and ld didn't have any problems, but even after the link was in place, it still didn't work. I had to reboot (but nothing else), after which it did work. No idea why that made any difference. ----------------------------------------------------------------------------- From: adb@geac.com (Anthony DeBoer) Organization: Geac Computer Corporation In article JRowe@cen.ex.ac.uk (J.Rowe) writes: >One thing I would like all vendors to do (I know one or two do) is >to give root the option of logging in using another shell. Am I the >only one to have mangled a root shell? This actually leads me back to a Unix admin horror story. At a former employer, I once watched our sysadmin reboot from the distribution tape after making a typing error editing the root line in /etc/passwd. After munging the colon count in this line, nobody could login or su, and he hadn't left himself in root in another session while testing his changes (a rule I've adopted for myself). My "big break", the moment I became sysadmin, was partly by virtue of being the only one to ask him for the root password the day he went out the door for the last time. What I've found preferable, when wanting to set up an alternative shell for root (bash, in my case), is to add a second line in /etc/passwd with a slightly different login name, same password, UID 0, and the other shell. That way, if /usr/local/bin/bash or /usr/local/bin or the /usr partition itself ever goes west, I still have a login with good ol' /bin/sh handy. (I know, installing it as /bin/bash might bypass some potential problems, but not all of them.) This might, of course, be harder to do on a security fascist system like AIX. Simply trying to create a "backup" login with UID 0 there once so that the operator didn't get a prompt and have to remember what to type next was a nightmare. (I wound up giving "backup" a normal UID, put it in a group by itself, and gave it setuid-root copies of find and cpio, with owner root, group backup, and permissions 4550). BTW, this was to make things easier for the backup operator, not to make it secure from that person. ----------------------------------------------------------------------------- From: williams@nssdcs.gsfc.nasa.gov (Jim Williams) Organization: NASA Goddard Space Flight Center, Greenbelt, Maryland Well, I guess I'll throw in a couple of stories too. The first isn't really a horror story, more of an unexpected failure mode. Story One is about The Sun 3/260 That Froze Solid. One day a user reported that the Sun 3/260 he was using was "dead". On inspection, I found the Sun at the console prompt and the keyboard totally unresponsive. The L1-A sequence did nothing. So I power cycled it. Nothing. A blank screen, no activity. I was ready to call service, then decided to try rebooting with the normal/diag switch set to diag. On looking at the back of the pedestal, I saw that the ethernet cable had been pressed up against the reset switch! ARGGGHHHH! The user had pushed the machine back just enough to press the switch and keep it pressed. (I don't recall if there was a "watchdog reset" message on the console when I found it, but I was new enough to Suns that that would not have been a dead givaway.) Story Two involved connecting an HP laserjet to a Sun 3/280. This sucker just would NOT do flow control correctly. I put a dumb terminal in place of the HP and manually typed *S/*Q sequences to prove that the serial port really was honoring X-ON/X-OFF. But for some reason the *Ss from the HP didn't "taste right" to the Sun, which ignored them. Switching the HP serial port between RS422/RS232 had no effect. It evenually turned out to be some sort of flakeyness with the Sun ALM-II board. Everything worked fine after I moved the printer to one of the built-in Zilog ports. Death to flakey hardware... Cheers! Jim ----------------------------------------------------------------------------- From: rick@sadtler.com (Rick Morris) Organization: Sadtler Research Laboratories Slightly off the subject, but not too far off, is the phenomenon of "Sysadmin Wannabees." I've been Sys Admin of UNIX at 3 sites now. The phenomenon has occured at all three. You are talking to a fellow programmer, or a programmer is within ear shot. A new user (or even an old user) comes up to you and asks something like: "How would I list only directory files within a directory?" Now it has been my experience that the question is not complete. Is this a recursive list? Is this a "one-time" thing, or are you going to do it many times? Is it part of a program? (Sometimes questions like this end up as an answer to a C question executed as a system(3) call rather than a preferred library call.) Anyway, as you ponder the question, the many alternatives (in unix there's always another way), the questioner's experience, whether or not they want a techie answer or a DOSie answer, the programmer within ear shot pipes in with an answer of how *THEY* do or would do it. It is invariable. It happens every time. I don't think I take all that long to answer. But the Wannabee answer is rapid. Like the kid in class who raises his hand going "oo" "oo" "oo". I have seen my predicessors get all bent out of shape when the Sysadmin Wannabees jump on their toes. I usually let the answer proceed, indeed, often these Wannabees give a complete answer, even doing it for the questioner. After a bit I return to the questioner and ask if the question was properly answered, if they understand the answer, or if they want any more information. It also shows me how deeply the Wannabee understands just what is going on inside that pizza box. Have any other of you sys admins seen this phenomenon, or is it my slow pondering of potential answers that drives the Wannabee to jump in? -Rick. ----------------------------------------------------------------------------- From: rslade@cue.bc.ca (Rob Slade) Organization: Computer Using Educators of B.C., Canada Hope this fits. I had a job one time teaching Pascal at a "visa school". The machine was a multi-user micro that ran UNIX. I have enough stories from that one course to keep a group of computer educators in stitches for at least half an hour. The finale of the course was on the last day of classes. When I showed up and powered up the system, it refused to boot. Since all the students' term projects and papers were in the computer, it was fairly important. After a few hours of work, and consultation with the other teacher, who did the sysadmin and maintenance, we were finally informed that the new admin assistant around the place had decided that the layout of the computer lab was unsuitable. (I had noticed that all the desk were repositioned: I thought the other teacher had done it, he thought I had.) The AA had, the night before, moved all the furniture, including the terminals and the micro. She did not know anything about parking hard disks. We knew now, that we were in trouble, but we didn't realize how much until we started reading up on emergency procedures. For some unknown reason, booting the micro from the original system disks would automatically reformat the hard disk. (The visa school refunded the tuition for all the students in that course.) ----------------------------------------------------------------------------- From: keith@ksmith.uucp (Keith Smith) Organization: Keith's Computer, Hope Mills, NC My dumbest move ever. Client in Charlotte, NC (3 hours + away) has Xenix box with like 15 users running single app. They have a tape backup of course. Anyway they ran slam out of space on the 70MB disk drive so I upgraded them from an MFM to a SCSI 150MB disk. Restored their app & data files, and they were off and running. Anyway they did an application directories backup (tar) on a daily basis and backed the rest of the system up with tar on Monday morning. Being a nice guy I built a menu system and installed the backups on the menu so they could do it with a push of the button. Swell, It's Monday Call if anything else comes up. 1 week later I get a call. Console is scrolling messages, App seems to be missing yesterday's orders, etc. Call in, and cannot log in. 'w' doesn't work. Crazy stuff. Really strange. Grab old drive/controller, fly to Charlotte replace drive, install app backup tape. They re-key missing stuff, etc. Bring new disk back. Won't boot, won't do anything. Boot emergency floppy set. Looking around. Can't figure but have backup tape from that morning that "completed successfully". tar tvf /dev/rct0. Hmm, why all these files look very OLD. Uh, Where, Uh. Look at menu command for the "backup" is 'tar xvf /dev/rct0 /' Anyway, I owned up to the mistake, re-loaded the SCSI drivers and changed the command to 'tar cvf ..' Hehehe, Now I DOUBLE check what I put on a menu, and try not to be in a *HURRY* when I do this stuff. ----------------------------------------------------------------------------- From: ken@sugra.uucp (Kenneth Ng) Organization: Private Computer, Totowa, NJ In article <1992Oct16.152629.29804@nsisrv.gsfc.nasa.gov: williams@nssdcs.gsfc.nasa.gov (Jim Williams) writes: :Story Two involved connecting an HP laserjet to a Sun 3/280. This :sucker just would NOT do flow control correctly. I put a dumb :terminal in place of the HP and manually typed *S/*Q sequences to :prove that the serial port really was honoring X-ON/X-OFF. But for :some reason the *Ss from the HP didn't "taste right" to the Sun, which :ignored them. Switching the HP serial port between RS422/RS232 had no :effect. It evenually turned out to be some sort of flakeyness with :the Sun ALM-II board. Everything worked fine after I moved the :printer to one of the built-in Zilog ports. Death to flakey hardware... ARRRGGGHHH!!!! DEATH TO ALM-II BOARDS! Funny though, I do have an HPLJ-2 hooked up to a SUN 690MP through the ALM-2 boards without problems. However I also had Sun going up the wall with myself with an Okidata 320 printer that would hang the port until we reboot the machine (not a nice thing to do with a dozen stock brokers). Funny thing is, we had ANOTHER Okidata 320 printer attached to the same Sun on another ALM-2 port, no problem with that one. Hm, switch the printers, no change. Switch the cables, no change. Switch the ports, no change. Wierd. Finally discovered it was the DATA that was being sent. The printer with problems was a label printer, which was sending a control-s every 10-20 characters or so to pause the Sun. Apparently the Sun ALM-2 drivers can not handle control-s'es too frequently. No problem, Sun said, just switch to hardware flow control. Puzzled me, because my docs said the ALM boards had no hardware flow control. But his docs said they were there. Took the printer off line, started the lpd, data scope showed the data going out. Talked to Sun again, tried RTS-CTS, DTR, 'crtscts' in printcap, '-crtscts' in printcap. Trying all kinds combinations. Finally he asked me which ALM-2 port I was using, 13 I responded. Oh, ALM-2 ports only have the hardware flow control in the first four ports. Whoops :-). Both docs were, true, my docs said there was no hardware flow control, which was right, on the last 12 ports. His docs said that there was hw flow control, but he missed the 'on the first four ports' part. Now it works, and I hope Sun now has this better documented. ----------------------------------------------------------------------------- From: corwin@ensta.ensta.fr (Gilles Gravier) Organization: ENSTA, Paris, France Well, talk about horror stories... We have a DataGeneral Aviion machine where I work at. I was doing regular admin tasks on it and decided, logged in as root, to clean /tmp... (I can already see you laughing there!). So, as usual, I typed "cd / tmp" then "rm *" as I was placed in / when the dreaded rm was entered... My root directory was erased... I realized my error fast enough... So, since I had deleted the kernel, and the administration kernels (that both reside in /), I had to recreate a new kernel. Luckily for me, DG/UX allows to recreate one "on the fly", using parameters of the running kernel (in memory!)... So I did, and then rebooted. Things started getting bad when I still couldn't work on my machine, logins didn't work (No Shell messages...)... Until I could access the /etc/passwd file using a trojan shell through an NFS mounted directory, and great a root account whose shell was not /sbin/sh... On a DG, /sbin and /bin are both links to /usr/sbin... The links were killed when I did my "rm"... Well, now I do backups! Gilles. ----------------------------------------------------------------------------- From: corwin@ensta.ensta.fr (Gilles Gravier) Organization: ENSTA, Paris, France I am sysadmin at my office... I won't name it, because that's not the subject... Of course, UNIX is my cup of tea... But, at home, I have an MS DOS machine... As old habits die hard, I have set up MKS toolkit on my home PC... And, as I have a C:\TMP directory where Windows and other applications put stuff, that remains, as I sometimes have to reboot fast... (ah, the fun of developping at home!)... So, in my AUTOEXEC.BAT file, I have the following: rm -rf /tmp mkdir c:\tmp the recursive rm comming from MKS, and mkdir from horrible MSDOS. At the time, I didn't have a tape streamer on my pc... I was working, and the mains waint down... so did the PC. Windows was running, \TMP full of stuff... So, when powers comes back on, rm -rf /tmp has things to do... While it's doing those things, power goes down again (there was a storm). Power comes back up, and this time, it seems that the autoexec takes really too much time... So, I control C it... And, to my horror, realize that I don't have anymore C:\DOS C:\BIN C:\USR and that my C:\WINDOWS was quite depleted... After some investigation, unsuccesfull, I did the following: cd \tmp and then DIR... And there, in C:\TMP, I find my C:\ files! The first power down had resulted in the cluster number of C:\ being copied to that of C:\TMP, actually resulting in a LINK! (Now, this isn't suppose to happen under MSDOS!) I had to patch in the DIRECTORY cluster to change TMP's name replacing the first T by the letter Sigma, so that DOS tought that TMP wasn't there anymore, then do an chkdsk /F, and then undelete the files that I could... And rebuild the rest... Took me some time! Gilles. ----------------------------------------------------------------------------- From: erik@src4src.linet.org (Erik VanRiper) Organization: The Source for Source Here's one for ya... I run on a 386/25. Small system, 4 inbound lines, etc. I was installing a new SCSI drive to complement my 2 MFM's. Took me forever to get everything just right. Things finally worked, so I figured I would shutdown and play with the jumper settings to see what this thing could do. What did I do? Well, I just turned off the power, that's all. erk. Just rebuilt the kernal, did not do a haltsys, or a shutdown, or anything. Just shut the power off. ARGH! Took me 3 weeks to clean up the mess. You tend to get in this cycle of "try" "haltsys" "power off" "change jumpers" "power on" "try". Well, once everything worked, I guess I was a wee bit excited and forgot a step. :-) Granted, not a very good story, but I will tell you about my "cardboard teepee" of a computer case sometime. :-) ----------------------------------------------------------------------------- From: mike@pacsoft.com (Mike Stefanik) Organization: Pacific Software Group, Riverside, CA One of the more interesting problems that I ran into was a customer that was having problems with their SCSI tape drive on a XENIX box. Around midnight, every night, the system would automatically backup and verify their data. One day, the customer needed to restore some data files from the last night's backup. She called because, although the restore worked just fine, she didn't see the busy light on the drive come on, and it didn't sound like the tape was moving. I dialed up the system, had her put a tape in and did a retension -- the drive started winding the tape back and forth, and we both concluded that she was mistaken. After all, the tape was retensioning, and she wasn't getting any backup or verify errors at all. I just chalked this one up to user confusion. A few days later, she called back saying that there really is something wrong with the tape. She needed to restore some data from a few days ago, and like before, the busy light on the drive didn't come on, but files did restore. However when she started the application program, the data hadn't changed. I dialed up the system again, and just on a fluke, issued a "df" -- it showed their rather large root filesystem to be nearly full. Confused, I did a "find", searching for files over 1MB. Of course, what I found was this huge file named /dev/rct0. As I later discovered, their system had crashed a few weeks ago, and she had simply answered "yes" to a bunch of questions that it asked when she brought it back up. The /dev/rct0 device was removed (but /dev/xct0 was still there, which allowed me to retension the tape) and the backup script never checked to make sure that it was actually writing to a character device. Needless to say, I modified the backup program to make sure that it was really writing to a device, and I made her promise to call me whenever the system crashed or asked "funny questions" when it was booting. ----------------------------------------------------------------------------- From: gert@greenie.gold.sub.org (Gert Doering) russells@ccu1.aukuni.ac.nz (Russell Street) writes: >So when I came in this morning a user's session had crashed while >he was replying to mail and emacs had spent the night quietly >filling up the root partion (where /tmp) was. Well... sounds familiar... I was on a 5 days vacation, the first day my machine crashed... How? Well... cron started a shell-skript to extract some files from a ".lzh"-Archive. LHarc found that the target file already existed, asked "file exists, overwrite (y/n)?" ... since it was started from cron, it just read "EOF". Tried again. Read "EOF". And so on. All output went to /tmp... what was full after the file reached 90 MB! What happened next? I'm using a SCO machine, /tmp is in my root filesystem and when trying to login, the machine said something about being not able to write loggin informations - and threw me out again. Switched machine off. Power on, go to single user mode. Tried to login - immediately thrown out again. I finally managed to repair the mess by booting from Floppy disk, mounting (and fsck-ing) the root filesystem and cleaning /tmp/* gert ----------------------------------------------------------------------------- From: gert@greenie.gold.sub.org (Gert Doering) Organization: GreeniE npm@dale.cts.com (Nancy Milligan) writes: >About three days later almost every file on this machine had been deleted or >compressed. Apparently I got distracted by something while I was writing >the config file, and the entry that was supposed to be for /tmp said /. >Boy, did I feel like an ijjit. Ever did # find / -atime +14 -exec rm -f {} \; instead of # find /tmp -atime +14 -exec rm -f {} \; [corrected from a later post - ed.] and then wondered why it took so long to clean up 20 files under /tmp? gert ----------------------------------------------------------------------------- From: dbriggs@zia.aoc.nrao.edu (Daniel Briggs) Organization: National Radio Astronomy Observatory, Socorro NM Did anyone by chance archive the post of a year or so ago where someone described the recovery of a Unix box from a partial "rm -r *" (where root forgot that he was in /) ? They had lost everything up to (and including?) /etc before the command was stopped. I seem to recall that they would lose everything on the disk if they reinstalled the system, so there were very good reasons to try and restore the barely running system. Of course almost all of the utilities that they needed to do it had lived in /bin. There were a few goodies in /usr/5bin that helped them out. The fix eventually involved writing a bootstrap network utility on another machine, and assembling it there, typing in the binary in an emacs process that was still running, and overwriting some other system utility that had the correct execute permissions, (since they couldn't chmod anything!). It was a wonderful example of recovery from a near fatal error. If it floats my way again, I'd love to get a copy of that post. ----------------------------------------------------------------------------- From: night@acm.rpi.edu (Trip Martin) Yup, I saved a copy because it was such a classic story. It's apparently been re-posted every so often for a number of years, and it's worth posting again. So here it is... ----- From alt.folklore.computers Fri Nov 9 11:16:43 1990 Path: rpi!zaphod.mps.ohio-state.edu!usc!cs.utexas.edu!utgpu!utzoo!sq!msb From: msb@sq.sq.com (Mark Brader) Newsgroups: alt.folklore.computers Subject: rm -rf / (was Hex vs. Octal) Summary: repost Message-ID: <1990Nov8.082550.26347@sq.sq.com> Date: 8 Nov 90 08:25:50 GMT References: <1990Nov5.173048.8998@hq.demos.su> Organization: SoftQuad Inc., Toronto, Canada Lines: 184 Status: OR > ... if you're trying rm -rf / you'll NEVER get a clear disk - at least > /bin/rm (and if it reached /bin/rmdir before scanning some directories > then add a lot of empty directories). I've seen it once... Then it must be version-dependent. On this Sun, "cp /bin/rm foo" followed by "./foo foo" does not leave a foo behind, and strings shows that rm appears not to call rmdir (which makes sense, as it can just use unlink()). In any case, I'm reminded of the following article. This is a classic which, like the story of Mel, has been on the net several times; it was in this newsgroup in January. It was first posted in 1986. ----- Have you ever left your terminal logged in, only to find when you came back to it that a (supposed) friend had typed "rm -rf ~/*" and was hovering over the keyboard with threats along the lines of "lend me a fiver 'til Thursday, or I hit return"? Undoubtedly the person in question would not have had the nerve to inflict such a trauma upon you, and was doing it in jest. So you've probably never experienced the worst of such disasters.... It was a quiet Wednesday afternoon. Wednesday, 1st October, 15:15 BST, to be precise, when Peter, an office-mate of mine, leaned away from his terminal and said to me, "Mario, I'm having a little trouble sending mail." Knowing that msg was capable of confusing even the most capable of people, I sauntered over to his terminal to see what was wrong. A strange error message of the form (I forget the exact details) "cannot access /foo/bar for userid 147" had been issued by msg. My first thought was "Who's userid 147?; the sender of the message, the destination, or what?" So I leant over to another terminal, already logged in, and typed grep 147 /etc/passwd only to receive the response /etc/passwd: No such file or directory. Instantly, I guessed that something was amiss. This was confirmed when in response to ls /etc I got ls: not found. I suggested to Peter that it would be a good idea not to try anything for a while, and went off to find our system manager. When I arrived at his office, his door was ajar, and within ten seconds I realised what the problem was. James, our manager, was sat down, head in hands, hands between knees, as one whose world has just come to an end. Our newly-appointed system programmer, Neil, was beside him, gazing listlessly at the screen of his terminal. And at the top of the screen I spied the following lines: # cd # rm -rf * Oh, shit, I thought. That would just about explain it. I can't remember what happened in the succeeding minutes; my memory is just a blur. I do remember trying ls (again), ps, who and maybe a few other commands beside, all to no avail. The next thing I remember was being at my terminal again (a multi-window graphics terminal), and typing cd / echo * I owe a debt of thanks to David Korn for making echo a built-in of his shell; needless to say, /bin, together with /bin/echo, had been deleted. What transpired in the next few minutes was that /dev, /etc and /lib had also gone in their entirety; fortunately Neil had interrupted rm while it was somewhere down below /news, and /tmp, /usr and /users were all untouched. Meanwhile James had made for our tape cupboard and had retrieved what claimed to be a dump tape of the root filesystem, taken four weeks earlier. The pressing question was, "How do we recover the contents of the tape?". Not only had we lost /etc/restore, but all of the device entries for the tape deck had vanished. And where does mknod live? You guessed it, /etc. How about recovery across Ethernet of any of this from another VAX? Well, /bin/tar had gone, and thoughtfully the Berkeley people had put rcp in /bin in the 4.3 distribution. What's more, none of the Ether stuff wanted to know without /etc/hosts at least. We found a version of cpio in /usr/local, but that was unlikely to do us any good without a tape deck. Alternatively, we could get the boot tape out and rebuild the root filesystem, but neither James nor Neil had done that before, and we weren't sure that the first thing to happen would be that the whole disk would be re-formatted, losing all our user files. (We take dumps of the user files every Thursday; by Murphy's Law this had to happen on a Wednesday). Another solution might be to borrow a disk from another VAX, boot off that, and tidy up later, but that would have entailed calling the DEC engineer out, at the very least. We had a number of users in the final throes of writing up PhD theses and the loss of a maybe a weeks' work (not to mention the machine down time) was unthinkable. So, what to do? The next idea was to write a program to make a device descriptor for the tape deck, but we all know where cc, as and ld live. Or maybe make skeletal entries for /etc/passwd, /etc/hosts and so on, so that /usr/bin/ftp would work. By sheer luck, I had a gnuemacs still running in one of my windows, which we could use to create passwd, etc., but the first step was to create a directory to put them in. Of course /bin/mkdir had gone, and so had /bin/mv, so we couldn't rename /tmp to /etc. However, this looked like a reasonable line of attack. By now we had been joined by Alasdair, our resident UNIX guru, and as luck would have it, someone who knows VAX assembler. So our plan became this: write a program in assembler which would either rename /tmp to /etc, or make /etc, assemble it on another VAX, uuencode it, type in the uuencoded file using my gnu, uudecode it (some bright spark had thought to put uudecode in /usr/bin), run it, and hey presto, it would all be plain sailing from there. By yet another miracle of good fortune, the terminal from which the damage had been done was still su'd to root (su is in /bin, remember?), so at least we stood a chance of all this working. Off we set on our merry way, and within only an hour we had managed to concoct the dozen or so lines of assembler to create /etc. The stripped binary was only 76 bytes long, so we converted it to hex (slightly more readable than the output of uuencode), and typed it in using my editor. If any of you ever have the same problem, here's the hex for future reference: 070100002c000000000000000000000000000000000000000000000000000000 0000dd8fff010000dd8f27000000fb02ef07000000fb01ef070000000000bc8f 8800040000bc012f65746300 I had a handy program around (doesn't everybody?) for converting ASCII hex to binary, and the output of /usr/bin/sum tallied with our original binary. But hang on---how do you set execute permission without /bin/chmod? A few seconds thought (which as usual, lasted a couple of minutes) suggested that we write the binary on top of an already existing binary, owned by me...problem solved. So along we trotted to the terminal with the root login, carefully remembered to set the umask to 0 (so that I could create files in it using my gnu), and ran the binary. So now we had a /etc, writable by all. From there it was but a few easy steps to creating passwd, hosts, services, protocols, (etc), and then ftp was willing to play ball. Then we recovered the contents of /bin across the ether (it's amazing how much you come to miss ls after just a few, short hours), and selected files from /etc. The key file was /etc/rrestore, with which we recovered /dev from the dump tape, and the rest is history. Now, you're asking yourself (as I am), what's the moral of this story? Well, for one thing, you must always remember the immortal words, DON'T PANIC. Our initial reaction was to reboot the machine and try everything as single user, but it's unlikely it would have come up without /etc/init and /bin/sh. Rational thought saved us from this one. The next thing to remember is that UNIX tools really can be put to unusual purposes. Even without my gnuemacs, we could have survived by using, say, /usr/bin/grep as a substitute for /bin/cat. And the final thing is, it's amazing how much of the system you can delete without it falling apart completely. Apart from the fact that nobody could login (/bin/login?), and most of the useful commands had gone, everything else seemed normal. Of course, some things can't stand life without say /etc/termcap, or /dev/kmem, or /etc/utmp, but by and large it all hangs together. I shall leave you with this question: if you were placed in the same situation, and had the presence of mind that always comes with hindsight, could you have got out of it in a simpler or easier way? Answers on a postage stamp to: Mario Wolczko ----- Trip Martin ----------------------------------------------------------------------------- From: exudnw@exu.ericsson.se (Dave Williams) Organization: Ericsson Network Systems A sysadmin was told to change the root passwd on a dozen or so Sun servers serving 400 diskless sun clients. He changed the passwd string to the wrong encrypted string (with a sed-like string editor) and locked root out from everywhere. Took hours to untangle. You only learn when you make mistakes... [stuff about dead presidents deleted] ----------------------------------------------------------------------------- From: almquist@chopin.udel.edu (Squish) Organization: Human Interface Technology Lab (on vacation) Two miserable flubs: 1) /etc/rc cleans tmp but it wasn't cleaning up directories so I changed the line: echo clearing /tmp (cd /tmp; rm -f - *) to echo clearing /tmp (cd /tmp; rm -f -r - *; rm -f -r - .*) About 15 minutes later I had wiped out the hard drive. 2) One of the user discs got filled so I needed to move everyone over to the new disc partition. So, I used the tar to tar command and flubbed: cd /user1; tar cf - . 3 (cd /user1; tar xfBp - ) Next thing I know /user1 is coming up with lots of weird consistency errors and other such nonsense. I meant to type /user2 not /user1. OOOPS! My moral of the story is when you are doing some BIG type the command and reread what you've typed about 100 times to make sure its sunk in (: ----------------------------------------------------------------------------- From: anne@maxwell.concordia.ca (Anne Bennett) Organization: Concordia University, Montreal, Canada After about four months as a Unix sysadm, and still feeling rather like a novice, I was asked to "upgrade" a Sun lab (3/280 server and ten 3/50 diskless clients) from SunOS 4.0.3 to 4.1 -- of course, this "upgrade" was actually a complete re-install. Well, the server had no tape drive, not even any SCSI controller. There were no other machines on its subnet other than the clients, so I had no boothost (at that time, I did not know that the routers could be reconfigured to pass the appropriate rarp packets, nor do I think our network people would have taken kindly to such a hack!). The clients did have SCSI controllers, but I had no portable tape drive. Luckily, I had a portable disk. So, with great trepidation (remember, I was still a novice), I set up one of the clients, with the spare disk, to be a boothost. I booted the server off the client and read the miniroot from a tape on a remote machine, and copied it to the server's swap partition. Then I manually booted the miniroot on the server by booting off the temporary boothost with the appropriate options, and specified the server's swap partition as containing the kernel to be loaded. Once in the miniroot, I started up routed to permit me to reach the tapehost, and finally invoked suninstall. From then on, it worked like a charm. Needless to say, I was extremely pleased with myself for figuring all of this out. I then settled down to do the "easy stuff", and got around to configuring NIS (Yellow Pages). I decided to get rid of everything I didn't need, under the assumption that a smaller system is easier to understand and keep track of. The Sun System and Network Administration Manual, which is in many ways an admirable tome, had on page 476 a section on "Preparing Files on NIS Clients", which said: "Note that the files networks, protocols, ethers, and services need not be present on any NIS clients. However, if a client will on occasion not run NIS, make sure that the above mentioned files do have valid data in them." So I removed them. Several hours later, when I had finished configuring the server to my satisfaction, reloading the user files, etc., I finally got around to booting up the clients. Well, I *tried* to boot up the clients, but got the strangest errors: the clients loaded their kernels and mounted /, but failed trying to mount /usr with the message "server not responding. RPC: Unknown protocol". I was mystified. I tried putting back the generic kernels on server and clients, several different ifconfig values for the ethernet interfaces, enabling mountd and rexd on server's inetd.conf, removing the clients' /etc/hostname.le0 (which I had added)... all to no avail. 'Twas the last work day before the Christmas break, and I was flummoxed. Of course, I finally connected the error message "unknown protocol" with the removed /etc/protocols (and other) files, restored these files, after which everything was fine again. I was pretty mad, since I had wasted a whole day on this problem, but *technically*, the Sun manual above is correct. It just neglected to mention that of course, *no* machine is running NIS at boot time, therefore *every* machine needs valid data in the networks, services, protocols, and ethers files *at boot time*. Grrr! ---------------------------------------------------------------------------- From: rick@sadtler.com (Rick Morris) Organization: Sadtler Research Laboratories Okay, I'll bite. We had Zenith Data System's Z-286's, boosted to 386's via an excellerator (imagine a large boot stomping lots of data through a small 16 bit funnel...). We were running SCO's Xenix. The user filesystem crashed in such a way that it couldn't be repaired via fsck. fsck would try to repair a specific file and then just stop, leaving the filesystem dirty. The "dirty bit" in the superblock said that it couldn't be mounted because it was dirty. But it couldn't be cleaned. But there was lots of data on it and I hadn't been doing backups because the only I/O device to do backups was the floppy drive and I wasn't about to sit there every night or even once a week and slam 30 odd floppies into the drive while the backups ran, even worse try to restore a file from a backup of 30 floppies.... Anyway, to recover the data I used fsdb to edit the superblock and change the dirty bit to clean, mounted the disk, got off all the good data, and remade the filesystem. Thanks, Xenix. fsck couldn't clean it, but you did supply fsdb! *whew* -Rick. From: yared@anteros.enst.fr (Nadim Yared) Organization: Telecom Paris, France Well, My story happened on a Sun Sparcstation 2 I once wanted to update the libc.so.1.7 to libc.so.1.8 by myself, so I got root, and then ftp the /lib/libc.so.1.8 to my /lib. Unfortunately there was not enough room on this partition. So all i got was a file with zero length. The problem is that I ran /usr/etc/ldconfig in the directory /lib, and that was all. Every command could not be executed, cause ld.so checked for /libc.so.1.8, being the newest one. All i needed was a statically linked mv, but SUN does not provide usually the source. Even going single user didn't do anything. So i had to install a miniroot on the swap partition, and cp /bin/mv from the CD-ROM, and execute-it. It sounds like an american film : a happy ending saved my life. Nadim YARED. Ecole Nationale Superieure des Telecommunications de PARIS. ---------------------------------------------------------------------------- From: colston@gid.co.uk (Colston Sanger) Summary: Ah, the scratch monkey story.... Organization: GID Ltd, Upper Basildon, Reading, UK In article <1705@frackit.UUCP>, dave@frackit.UUCP (Dave Ratcliffe) writes: > In article <1992Oct14.214535.2176@sci34hub.sci.com>, gary@sci34hub.sci.com (Gary Heston) writes: > > In article <1992Oct7.120246.16981@multix.no>, aras@multix.no (Arne Asplem) writes: > > With all these stories, I'm suprised nobody has posted the "scratch monkey" > > story. Has that admin gone onto bigger and better things? > > ... If anyone > has access to the file in question I think now is an excellent time to > drag it out and regale us with it. Here it is: From eric@snark.thyrsus.com Sat Mar 30 23:19:09 1991 Subject: Apologies to all fans of Mabel! Followup-To: alt.folklore.computers In responding to several posters' pleas for the reinstatement of Mabel, I clean forgot that the condensed `Story of Mabel' wasn't added to the `scratch monkey' entry till 2.8.2, which most of you don't have. Here is the relevant bit from 2.8.5: @h{scratch monkey} n. As in, ``Before testing or reconfiguring, always mount a scratch monkey.'', a proverb used to advise caution when dealing with irreplaceable data or devices. Used to refer to any scratch volume hooked to a computer during any risky operation as a replacement for some precious resource or data that might get trashed. This term preserves the memory of Mabel, the Swimming Wonder Monkey, star of a biological research program at a great American university. Mabel was not (so the legend goes) your ordinary monkey; the university had spent years teaching her how to swim, breathing through a regulator, in order to study the effects of different gas mixtures on her physiology. Mabel suffered an untimely demise one day when a computer vendor @e{PM}ed the machine controlling her regulator (see also @e{provocative maintainance}). It is recorded that, after calming down an understandably irate customer sufficiently to ascertain the facts of the matter, the vendor's troubleshooter called up the @e{field circus} manager responsible and asked him sweetly ``Can you swim?''. The moral is clear: when in doubt, always mount a scratch monkey. See @e{scratch}. @refill I hope this satisfies Mabel's fans. The volume of the outcry for her resurrection has been remarkable (which is actually pleasant, because it vindicates my original idea that the story was worth including). Art Evans (the gentleman who posted the story to comp.risks) is doubtless an estimable person with whom I'd enjoy becoming acquainted, but a writer he is not. In particular, it always bothered me how he muffed the punch line... oh, heck, I guess I'll include the posting so you can see for yourself. ------------------------------------------------------------------------ The following, modulo a couple of inserted commas and capitalization changes for readability, is the exact text of a famous USENET message. The reader may wish to review the definitions of @e{PM} in the main text before continuing. Date: Wed 3 Sep 86 16:46:31-EDT From: "Art Evans" Subject: Always Mount a Scratch Monkey To: Risks@@CSL.SRI.COM My friend Bud used to be the intercept man at a computer vendor for calls when an irate customer called. Seems one day Bud was sitting at his desk when the phone rang. Bud: Hello. Voice: YOU KILLED MABEL!! B: Excuse me? V: YOU KILLED MABEL!! This went on for a couple of minutes and Bud was getting nowhere, so he decided to alter his approach to the customer. B: HOW DID I KILL MABEL? V: YOU PM'ED MY MACHINE!! Well, to avoid making a long story even longer, I will abbreviate what had happened. The customer was a Biologist at the University of Blah-de-blah, and he had one of our computers that controlled gas mixtures that Mabel (the monkey) breathed. Now, Mabel was not your ordinary monkey. The University had spent years teaching Mabel to swim, and they were studying the effects that different gas mixtures had on her physiology. It turns out that the repair folks had just gotten a new Calibrated Power Supply (used to calibrate analog equipment), and at their first opportunity decided to calibrate the D/A converters in that computer. This changed some of the gas mixtures and poor Mabel was asphyxiated. Well, Bud then called the branch manager for the repair folks: Manager: Hello B: This is Bud, I heard you did a PM at the University of Blah-de-blah. M: Yes, we really performed a complete PM. What can I do for you? B: Can you swim? The moral is, of course, that you should always mount a scratch monkey. ~~~~~~~~~~~~~~~~~~~~~~~~~~~ There are several morals here related to risks in use of computers. Examples include, ``If it ain't broken, don't fix it.'' However, the cautious philosophical approach implied by ``always mount a scratch monkey'' says a lot that we should keep in mind. Art Evans Tartan Labs ------------------------------------------------------------------------ Let's face it, people, that ending just does not work as well as it ought. The moral isn't ``always mount a scratch monkey''; sometimes you gotta use real monkeys, or you don't get any work done. The moral is properly ``*when in doubt* (that is, when you're going to do something that might crash the system)'' always mount a scratch monkey. I'm sure this is what Art meant, but it's not what he said. This and other infelicities in the writing (rambling prose, shaky punctuation, awkward anti-climactic appendix after the tildes etc.) made the scratch monkey appendix target #1 when it came to trim time. As much as possible, I tried to capture the flavor of the anecdote in my condensation without reproducing the bugs. Is that satisfactory? -- Eric S. Raymond = eric@snark.thyrsus.com (mad mastermind of TMN-Netnews) ---------------------------------------------------------------------------- From: valdis@vttcf.cc.vt.edu (Valdis Kletnieks) Organization: Virginia Tech, Blacksburg, VA Well, here's a few contributions of mine, over 10 years of hacking Unixoid systems: 1) yesterday's panic: Applying a patch tape to an AIX 3.2 system to bring it to 3.2.3. Having had reasonable sucess at this before, I used an xterm window from my workstation. Well, at some point, a shared library got updated.. I'd seen this before on other machines - what happens is that 'more', 'su', and a few other things start failing mysteriously. Unfortunately, I then managed to nuke ANOTHER window on my workstation - and the SIGHUP semantics took out all windows I spawned from the command line of that window. So - we got a system that I can login to, but can't 'su' to root. And since I'm not root, I can't continue the update install, or clean things up. I was in no mood to pull the plug on the machine when I didn't know what state it was in - was kind of in no mood to reboot and find out it wasn't rebootable. I finally ended up using FTP to coerce all the files in /etc/security so that I could login as root and finish cleaning up.... Ended up having to reboot *anyhow* - just too much confusion with the updated shared library... 2) Another time, our AIX/370 cluster managed to trash the /etc/passwd file. All 4 machines in the cluster lost their copies within milliseconds. In the next few minutes, I discovered that (a) the nightly script that stashed an archive copy hadn't run the night before and (b) that our backups were pure zorkumblattum as well. (The joys of running very beta-test software). I finally got saved when I realized the cluster had *5* machines in it - a lone PS/2 had crashed the night before, and failed to reboot. So it had a propogated copy of /etc/passwd as of the previous night. Go to that PS/2, unplug it's Ethernet.. reboot it. Copy /etc/passwd to floppy, carry to a working (?) PS/2 in the cluster, tar it off, let it propogate to other cluster sites. Go back, hook up the crashed PS/2s ethernet.. All done. Only time in my career that having beta-test software crash a machine saved me from bugs in beta-test software. ;) 3) Once I was in the position of upgrading a Gould PN/9080. I was a good sysadmin, took a backup before I started, since the README said that they had changed the I-node format slightly. I do the upgrade, and it goes with unprecidented (for Gould) smoothness. mkfs all the user partitions, start restoring files. Blam. I/O error on the tape. All 12 tapes. Both Sets of backups. However, 'dd' could read the tape just fine. 36 straight hours later, I finally track it down to a bad chip on the tape controller board - the chip was involved in the buffer/convert from a 32-bit backplane to a 8-bit I/O cable. Every 4 bytes, the 5th bit would reverse sense. 20 mins later, I had a program written, and 'dd 3 my_twiddle 3 restore -f -' running. Moral: Always *verify* the backups - the tape drive didn't report a write error, because what it *received* and what went on the tape were the same.... I'm sure I have other sagas, but those are some of the more memorable ones I've had... Valdis Kletnieks Computer Systems Engineer Virginia Tech