Pipe output of awk to kill -9

Question

I'm trying to kill any process that has to do with mysql. I'm piecing together a command, and so far, haven't come up with the right solution. One other consideration, is that the last process will correspond to the command 'grep mysql' - part of the command below. This process won't exist anymore by the time I try to kill it, so it needs to be excluded from the input piped to kill -9. Whats the best way to go about accomplishing this task? So far, I have the incomplete command:

ps -A | grep mysql | awk '{print $1}'

which has the (fake, for the purpose of this example) output

11111
22222
33333  # process id to be excluded

I was assuming I could pipe that to xargs kill -9 like so:

ps -A | grep mysql | awk '{print $1}' | xargs kill -9

and figure out a way to exclude the last pid, but everything I try does not seem to work correctly.

Answer 1

Probably the easiest thing to do here is to make grep not match its own command:

ps -A | grep [m]ysql | awk '{print $1}' | xargs kill -9

The brackets around the m make it a character set that only includes m, which doesn't change the pattern but won't match itself in the ps output. This is sort of the canonical way to avoid this issue. I'd also like to add that if you have the pkill command that running pkill -9 mysql is a bit easier.

It's also worth noting that you should avoid using SIGKILL (-9) when possible, as it does not give the target process a chance to exit gracefully. You should probably try with SIGTERM (default) first if you have not already.

Answer 2

Awk has a system() command that allows you to kill it directly ... Something like this.

ps ¦awk '/[m]ysql/{system( "kill -9 "$1)}'

The reason for the square brackets is similar to the previous. It prevents awk from being killed and closing the pipe.

The /string/ will perform grep-like line matching.

Answer 3

For completeness I would also suggest the commands pgrep and pkill.

• pgrep [-lf] [-u uid] [-other options] pattern list processes matching the extended regular expression pattern
• pkill [-f] [-t**SIGNAL] pattern kill processes matching pattern

The most interesting options, as indicated are probably

• -f match the complete command line of a process
• -u user only match a particular users processes (also, groups...)
• -l list the processes name/identifier (only pgrep)

For the others, see the fine manual.

All in all, these are much more versatile and usefull (in terms of beeing able to actually check what you kill before you do) than killall or the more complicated pipe recipes posted above.

Answer 4

To remove the last one from the list of PID's, you can use head -n N, where n is the number of PID's without the last one.

ps -A | grep mysql | awk '{print $1}' | head -n 2 | xargs kill -9

The assumption is that u know the number of PID that will be piped from grep.

Answer 5

Or the

killall mysql 

command might do it for you. It uses names instead of PIDs.

Answer 6

kill -9 `ps aux | grep PROCESS_NAME | grep -v grep  |  cut -d' ' -f6`