[Symbiote]

    ps -ef | grep foobar

is more easily done with

    pgrep foobar

or perhaps

    pgrep -a foobar

[SEJeff]

or ps -ef | grep fo[o]bar

So you don't have to | grep -v grep :)

I ask people to explain what that does and how it works as a sysadmin interview question.

[notfoss]

That's nice. Apparently, we can place the brackets around any of the characters too! Can you explain how it works?

[SEJeff]

Sure, the square brackets in posix regex (used by grep) are for character ranges. You can wrap any single character in the brackets and it works the same.

So foob[a]r matches the literal string foobar. If you grepped foob[ab]r it would match both literal strings foobar and foobbr. However, it doesn't match the literal string foob[a]r because [] is a character range. To match that, you'd need to escape it something like foob\[a\]r, which would not match the literal string foobar. This is why you don't need grep -v grep

Understanding how and why this works will dramatically help you slice and dice text strings in a shell, so it makes a great SysAdmin interview question.

[nailer]

pgrep already excludes itself

[SEJeff]

Sure but that isn't often nearly as useful as something like:

ps -efH | grep foob[a]r

Where you can see the arguments and whatnot. Both are good to know.

You can use awk's ability to do posix regex and emulate pgrep with:

ps -efH | awk '/foob[a]r/{print $1}'