Working with Processes in Unix

There are two commands heavily used by developers for checking their pocesses in unix.

1. Firstly it is the search for processes

ps -ef | grep search_process

or

ps aux | grep search_process

what’s the difference, well both do the same task

link

Both list all processes of all users. In that aspect -e and ax are completely equivalent. Where they differ is output format specifier, -f is “full”, while u is “user-oriented”. The displayed columns are different: columns for ps -f UID PID PPID C STIME TTY TIME CMD

columns for ps u USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND

The difference between ps -ef and ps aux is due to historical divergences between POSIX and BSD systems. At the beginning, POSIX accepted the -ef while the BSD accepted only the aux form.

1. Secondly to kill the process that we just found

kill -9 pid

or

kill -SIGKILL PID

or if we know the process name and if the unix system supports

killall nginx

Tip: What if we need to kill all the processes that starts with ‘schedule’. Here it is..

ps aux | grep schedule | grep -v grep | awk '{print $2}' | xargs kill -9

A quick description of the steps:

1. “ps aux | grep schedule” searches for the processes by the name schedule and returns the rows
2. “grep -v grep” excludes grep from the searched process list (rows)
3. “awk ‘{print $2}’” prints the second column of all the values returned. Which is mostly the process Id, if not choose the corresponding column by its number of appearance in the rows returned
4. “xargs kill -9” sends the kill signal to all the selected process Ids

Please make sure that you are searching for the right processes before killing them.

Any questions on this, please feel free to ask. We’re here to help…