This checks if a daemon is running, if not it starts the daemon. Great for daemons that need to always be running. Can be used with cron

ps -C someprogram || { someprogram & }

// sil at infiltrated dot net

Grepping for a process will return the grep command, this can be avoided by adding '| grep -v grep' to a command or easier in some cases altering the regular expression by adding brackets around a character.

ps | grep 'ss[h]'

The regular expression 'ss[h]' matches the literal string 'ssh' when it appears in the process list, but does not accidentally match the string 'ss[h]' when it appears in the process list as 'grep ss[h]'.

You probably use the ps command a lot, but sometimes there is too much info, and somewhat disordered. It can be easily ordered with the forest option, as the following example shows:

$ ps -e -o pid,args --forest

Display the top ten running processes - sorted by memory usage

ps aux | sort -nk +4 | tail

ps returns all running processes which are then sorted by the 4th field in numerical order and the top 10 are sent to STDOUT.

ps -eo pid,args | awk '/sleep/ && !/awk/{ system("kill -9 "$1)}'