Getting the pid's of a program line by line

Question

I can find the pid's of my program instances by issuing command like this:

pidof avconv

Which is giving me results

16616 16283 16279 16198 16175 16035 15073 14049 4922

But how can I output the same result line by line, like:

16616 
16283 
16279 
16198 
16175 
16035 
15073 
14049 
4922

Answer 1

You could parse the output with sed, as suggested by @Sobrique, or with tr:

pidof avconv | tr ' ' '\n'

Another approach would be to use pgrep instead:

$ pgrep avconv16616 
16283 
16279 
16198 
16175 
16035 
15073 
14049 

Answer 2

You can just get it that way in the first place...

ps -C avconv -o pid=

Answer 3

You can always use sed to insert some linefeeds

pidof avconv | sed 's/ /\n/g'

although perhaps a bigger question is - why do you need them on separate lines? It may be that there's a more appropriate answer.

Answer 4

There are multiple ways to do it depending upon your need.

1. If you are doing it in a shell script

   for line in $(pidof avconv)
   do
     echo $line
   done
   

2. If you are looking for a oneliner

   pidof avconv |perl -pne 's|\s+|\n|g' 
   

Answer 5

If you're using pidof on a Linux system, it may be possible to tell the utility to use a newline as the delimiter instead of space using its -d option:

pidof -d $'\n' /usr/sbin/apache2

Answer 6

Try this as well

ps ax | grep "program name, or part of it"

You will get the right answer, but also a meaningless entry like:

11424 pts/3    S+     0:00 grep --color=auto something

Using awk to show only PID's:

ps ax | grep "program name, or part of it"| awk '{print $1}'

That will give you the PID's, but also the PID of the meaningles entry. This entry is usually the last, so just leave it out.