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There are some bad things that can happen in the UNIX shell. Ofc. unset (empty) variables "rm -rf ${variable}/" ... I guess paths are given without a slash at

There are some bad things that can happen in the UNIX shell. Ofc. unset (empty) variables "rm -rf ${variable}/" ... I guess paths are given without a slash at the end (also for that reason). But also other commands: "hostname", if you type "hostname help" then your new hostname is set to "help". For us that means a full rebuild/reinstallation of the machine is necessary. This surely has been discussed before, but why not (again): Let me know of your horror stories, if you like.

billybofh 12y ago
A really simple typo - but it's always stayed with me. Many years ago on a Very Important Solaris Box(TM) I wanted to check when it had rebooted a few months before, so typed "last | grep reboot". Only I forgot to put in the 'grep'... (and if you're not a Solaris person - 'reboot' is pretty brutal on it - you may as well just pull the power cable out the back). What a fun day that was....
mqsiuser 12y ago
The similarity of "rm -rf *" and "rm -rf /" makes me nervous any time I "cd" somewhere and then issue the first. There is no trash can in my Unix, deleted is gone forever. A move (mv) or copy (cp) just overwrites files with the same name (as default) Right clicking (&executing everything (every line) that just got pasted from the current clipboard/copy-buffer)
- dannypgh 12y ago
  Why would you cd somewhere and then do rm -rf * when you can just rm -rf somewhere? Having your shell expand * is just asking for trouble; on most systems you'll have no problems creating more entries in a directory than you can specify arguments on the command line, so rm -rf * will not work from 'somewhere' but rm -rf somewhere should still work fine.
jafaku 12y ago
I started using these recently: set -o nounset set -o pipefail set -o errexit set -o xtrace I added them to all my scripts, and I also added all except errexit to ~/.bashrc The first one would save you from unset variables.
- vlisivka 12y ago
  You might be interested in bash-modules library, which is written with these options in mind.
scarygliders 12y ago
Being primarily used to, and mainly using Linux. Then using the killall command on a Solaris box, which just happened to be running the company's Oracle database... Cue the support line phone ringing off its hook. Cue BOFH Excuse : "Hmm it appears the server running the database has crashed. We're rebooting it now", etc etc. Lesson learned : killall on a Sun/Solaris box behaves VERY differently from the killall on Linux :D
marcosdumay 12y ago
The other classic rm: "rm * .o" That's what taught me the importance of backups.
lmm 12y ago
> if you type "hostname help" then your new hostname is set to "help". For us that means a full rebuild/reinstallation of the machine is necessary. What the hell? Why not just change it back?
- mqsiuser 12y ago
  I think the actual problem was that someone typed "hostname " (that is "hostname" and 2 blanks), which did set the hostname to " " (a blank). Yeah sure changing it back may work (it didn't for the colleagues that told me that). Here is another one: I once shut down a server because I wanted to know how to shutdown & reboot. I typed "shutdown -h" (I thought that would display help-pages :) It was the option to "halt" immediately. We needed to open a ticket to start the machine up again.

billybofh 12y ago

A really simple typo - but it's always stayed with me. Many years ago on a Very Important Solaris Box(TM) I wanted to check when it had rebooted a few months before, so typed "last | grep reboot". Only I forgot to put in the 'grep'... (and if you're not a Solaris person - 'reboot' is pretty brutal on it - you may as well just pull the power cable out the back). What a fun day that was....

mqsiuser 12y ago

The similarity of "rm -rf *" and "rm -rf /" makes me nervous any time I "cd" somewhere and then issue the first. There is no trash can in my Unix, deleted is gone forever. A move (mv) or copy (cp) just overwrites files with the same name (as default) Right clicking (&executing everything (every line) that just got pasted from the current clipboard/copy-buffer)

dannypgh 12y ago
Why would you cd somewhere and then do rm -rf * when you can just rm -rf somewhere? Having your shell expand * is just asking for trouble; on most systems you'll have no problems creating more entries in a directory than you can specify arguments on the command line, so rm -rf * will not work from 'somewhere' but rm -rf somewhere should still work fine.

jafaku 12y ago

I started using these recently: set -o nounset set -o pipefail set -o errexit set -o xtrace I added them to all my scripts, and I also added all except errexit to ~/.bashrc The first one would save you from unset variables.

vlisivka 12y ago
You might be interested in bash-modules library, which is written with these options in mind.

scarygliders 12y ago

Being primarily used to, and mainly using Linux. Then using the killall command on a Solaris box, which just happened to be running the company's Oracle database... Cue the support line phone ringing off its hook. Cue BOFH Excuse : "Hmm it appears the server running the database has crashed. We're rebooting it now", etc etc. Lesson learned : killall on a Sun/Solaris box behaves VERY differently from the killall on Linux :D

marcosdumay 12y ago

The other classic rm: "rm * .o" That's what taught me the importance of backups.

lmm 12y ago

> if you type "hostname help" then your new hostname is set to "help". For us that means a full rebuild/reinstallation of the machine is necessary. What the hell? Why not just change it back?

mqsiuser 12y ago
I think the actual problem was that someone typed "hostname " (that is "hostname" and 2 blanks), which did set the hostname to " " (a blank). Yeah sure changing it back may work (it didn't for the colleagues that told me that). Here is another one: I once shut down a server because I wanted to know how to shutdown & reboot. I typed "shutdown -h" (I thought that would display help-pages :) It was the option to "halt" immediately. We needed to open a ticket to start the machine up again.