New tools: pkill and pgrep

In Solaris 9, two new utilities were added: pkill and pgrep. These tools are perhaps old news to Solaris admins. However, these utilities were then quietly added to Linux in short order, and now show up in HP-UX 11i v3 and perhaps others. What do these tools do?

First of all, pkill is just a wrapper for pgrep. Well, what does pgrep do? It searches the current processes for a match based on arguments that you give to it.

The most common use would be to search for a command. The pgrep utility will then return each process ID, one per line. The pkill utility will send the default kill signal to each pid. The pgrep utility can search based on a large array of factors, including userid, groupid, virtual size, effective user ids, command name, full command string, and more.

Here’s an example:

# pgrep cache
13
12
14
15
33
49
22006
21950
21973
21976
#

When combined with scripting, these commands can be quite useful. Consider this ksh snippet:

for i in $(pgrep cache) ; do
  // do some commands here
done