Ylan Segal

Killing Me Softly

Every once in a while, a process is stuck and doesn’t want to respond. I usually just found the process id by using ps and then ran kill -9 <pid>. Why? Cargo-culting, mostly.

Recently a friend and co-worker shared with me a little bash function that will attempt to send less destructive signals to the process to allow it to have time to clean-up after itself. Eventually it ends up just sending the KILL signal, equivalent to -9.

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function mercy_kill() {
  pid=$1
  for signal in TERM INT HUP KILL; do
    cmd="kill -s ${signal} $pid"
    echo $cmd
    eval $cmd
    for i in {0..19}; do
      if [ $(ps -p $pid|wc -l) -lt 2 ]; then
        echo "pid $pid no longer exists"
        return 0
      fi
      sleep 0.1
    done
  done
}