What does ||: mean in the shell?

Question

I am looking at shell script code and I don't know what is the purpose of the double pipe (||) followed by a colon (:), can someone explain? eg.

   $ <some_command> >/dev/null 2>&1 || :

+3

theMarceloR 09 Sep 14 at 15:14

2 answers

: colon is noop, double is OR operation, so ...

execute some_command OR (if some_command fails) execute: (this is operation no)

|| means the second is executed only if the first command of the command fails. In this case, the second command means "do nothing"

+2

Davide 09 Sep '14 at 15:19

Charles duffy · Accepted Answer · 2014-09-09T15:16:28+0000

||

is boolean or.

:

is a no-op command that does nothing and exits with a truthful status.

So, anything || :

unconditionally returns true.

So some_command_that_may_fail ||:

it will always be successful.

This is important if there is an set -e

ERR or trap in use but you don't want your script to exit or throw an error if the command fails.