linux - Re-run bash script if another instance was invoked -


i have bash script may invoked multiple times simultaneously. protect state information (saved in /tmp file) script accesses, using file locking this:

do_something() { ... }  // check if there other instances of script; if exit exec 8>$lock if ! flock -n -x 8;         exit 1 fi  // script something... do_something

now other instance invoked when script running exits. want script run 1 time if there n simultaneous invocations, not n-times, this:

do_something() { ... }  // check if there other instances of script; if exit     exec 8>$lock     if ! flock -n -x 8;         exit 1     fi  // script something... do_something  // check if instance invoked, if re-run do_something again     if [ condition ];        do_something     fi

how can go doing this? touching file inside flock before quitting , having file condition second if doesn't seem work.

have 1 flag (lockfile) signal things needs doing, , set it. have separate flag unset execution part.

request_file=/tmp/please_do_something lock_file=/tmp/doing_something  # request running touch $request_file  # lock , run if ln -s /proc/$$ $lock_file 2>/dev/null ;     while [ -e $request_file ];         do_something         rm $request_file     done     rm $lock_file fi

if want ensure "do_something" run once each time whole script run, need create kind of queue. overall structure similar.


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