/usr/local/bin/once: call a command exactly once per uptime. useful for e.g. startx in .profile

once.zsh

#!/bin/zsh

test -e /dev/shm/once.db || touch /dev/shm/once.db

if grep -q "$*" /dev/shm/once.db
  then echo "$* already in oncedb" >&2
else
  echo "$*" >> /dev/shm/once.db
  "$@"
fi