limitprocess is a bashfunction which starts bash cmds but limits to maximum of N running instances (handy for cronjobs)

limitprocess.bash

# Starts bash cmds but limits to maximum of N running instances (handy for cronjobs)
# usage: ./limitprocess <max parallel processes> ..yourcommands..
# @dependancies: ps grep wc
# @param int maximum number of parallel processes
  
function limitprocess(){
  MAXINSTANCES="$1"; shift;
  processes=$(ps aux | grep "$*" | grep -v grep | wc -l )
  ((processes < MAXINSTANCES)) && "$@" || echo "already $MAXINSTANCES processes running"
}