Grep – Exclude Grep from Process List

greppidps

I have cobbled together a command to return the process ID of a running daemon:

ps aux | grep daemon_name | awk "{ print \$2 }"

It works perfectly and returns the PID, but it also returns a second PID which is presumably the process I'm running now. Is there a way I can exclude my command from the list of returned PIDs?

I've tested it a few times and it appears my command is always the second PID in the list, but I don't want to grab just the first PID in case it's inaccurate.

Best Answer

grep's -v switch reverses the result, excluding it from the queue. So make it like:

ps aux | grep daemon_name | grep -v "grep daemon_name" | awk "{ print \$2 }"

Upd. You can also use -C switch to specify command name like so:

ps -C daemon_name -o pid=

The latter -o determines which columns of the information you want in the listing. pid lists only the process id column. And the equal sign = after pid means there will be no column title for that one, so you get only the clear numbers - PID's.

Hope this helps.

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A Linux command to find files containing some strings but not another

There's more than one way to do it. This should keep the total number of processes executed to a minimum:

find . -name \*.xml -print0          \   # List of *.xml files (NUL-terminated)
  | xargs -0 grep -Zli 'string[12]'  \   # is input to first grep, which sends (NUL-term'd)
  | xargs -0 grep -Li  'string[34]'      # file list to second grep

Thanks Matt Gibson for reminding us of the -Z flag to GNU grep.

Grep -c gives inconsistent outputs

By default, pgrep checks the process name – which by default is the executable file name truncated to 16 bytes. To check the full command line as in ps aux, use the -f option.

pgrep -f "Xvfb" | wc -l

Compare: pgrep -l "Xvfb" and pgrep -lf "Xvfb".

Best Answer

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