A signal trap that logs when your script was killed and what other processes were running at that time

trap "echo \"$0 process $$ killed on $(date).\" | tee ${0##*/}_$$_termination.log; echo 'Active processes at the time were logged to ${0##*/}_$$_termination.log'; ps u >> ${0##*/}_$$_termination.log; exit " HUP INT QUIT ABRT TERM STOP
trap is the bash builtin that allows you to execute commands when the current script receives a particular signal. Uses $0 for the script name, $$ for the script PID, tee to output to STDOUT as well as a log file and ps to log other running processes.
Sample Output
./traptest.sh process 11009 killed on Wed Feb 18 12:08:09 PST 2009.
Active processes at the time were logged to traptest.sh_11009_termination.log

1
2009-02-18 20:13:29

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    godmachine81 · 2011-12-30 01:38:15 0

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    trap "echo \"$0 process $$ killed on $(date).\"; exit " HUP INT QUIT ABRT TERM STOP
    DEinspanjer · 2009-02-18 23:58:58 0
  • This is a 'killall' command equivalent where it is not available. Prior to executing it, set the environment variable USERNAME to the username, whose processes you want to kill or replace the username with the $USERNAME on the command above. Side effect: If any processes from other users, are running with a parameter of $USERNAME, they will be killed as well (assuming you are running this as root user) [-9] in square brackets at the end of the command is optional and strongly suggested to be your last resort. I do not like to use it as the killed process leaves a lot of mess behind.


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    ps -ef | grep $USERNAME | awk {'print $2'} | xargs kill [-9]
    TheNomad · 2009-02-17 20:35:35 1
  • Check out the usage of 'trap', you may not have seen this one much. This command provides a way to schedule commands at certain times by running them after sleep finishes sleeping. In the example 'sleep 2h' sleeps for 2 hours. What is cool about this command is that it uses the 'trap' builtin bash command to remove the SIGHUP trap that normally exits all processes started by the shell upon logout. The 'trap 1' command then restores the normal SIGHUP behaviour. It also uses the 'nice -n 19' command which causes the sleep process to be run with minimal CPU. Further, it runs all the commands within the 2nd parentheses in the background. This is sweet cuz you can fire off as many of these as you want. Very helpful for shell scripts.


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    ( trap '' 1; ( nice -n 19 sleep 2h && command rm -v -rf /garbage/ &>/dev/null && trap 1 ) & )
    AskApache · 2009-10-10 04:43:44 1

What Others Think

I like the concept, but maybe a simpler example to show how to use trap? It took me a minute to realize that the submission was one command that takes in a string and a list of signals. Either way, you definitely taught me new, very useful command! Cheers!
joem86 · 486 weeks and 6 days ago
Sure thing joem86! I posted it because it was something useful that I needed in this particular form, but a simplified example of trap is surely useful to others.
DEinspanjer · 486 weeks and 5 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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