What does the || : in this line of bash script from an rpm spec file do?

Question

ln -s /var/log/$SERVICE_NAME $RPM_INSTALL_PREFIX/logs || :

In the rpm spec file every line ends with || :

What is the significance of the || : and why is it there?

score 14 · Accepted Answer · answered Apr 21 '11 at 00:01

14

It causes any error to be ignored so that the rpm operation isn't canceled.

|| causes the next command to run if the previous command failed, and : always succeeds.

answered Apr 21 '11 at 00:01

score 3 · Answer 2 · answered Apr 21 '11 at 00:02

3

It swallows the exit code.

|| does the thing after it if the thing before it fails (i.e., has a non-zero exit code). : is the “do nothing” command. Put them together…

answered Apr 21 '11 at 00:02

Donal Fellows

score 2 · Answer 3 · edited Apr 21 '11 at 00:13

2

`||` is OR operator. `:` means "do nothing".

Your statement says, "do the soft linking or do nothing"

edited Apr 21 '11 at 00:13

pavium

answered Apr 21 '11 at 00:04

bash-o-logist

score 2 · Answer 4 · answered Jul 09 '11 at 14:11

2

I know others have answered, but I prefer to put:

command || /bin/true

IMHO that makes it a lot more obvious to the next person who is reading the bash script/spec file.

answered Jul 09 '11 at 14:11

Aaron D. Marasco

score 1 · Answer 5 · answered Apr 21 '11 at 00:06

1

It is simply means OR. You can try small testing like this

ls nofile-here-like || echo 'Not here'

If file not there echo will printed. Try with existing file, it will not

answered Apr 21 '11 at 00:06

Senthil

5 Answers5