what does grep -v '#' do?

sigint-ninja · 08-17-2018, 05:43 AM

does this command include or exclude comments starting with #
and sort them in reverse?

un1x · 08-17-2018, 05:46 AM

Code:

~$ grep -v 
Usage: grep [OPTION]... PATTERN [FILE]...
Try 'grep --help' for more information.

Code:

$ grep -v #
Usage: grep [OPTION]... PATTERN [FILE]...
Try 'grep --help' for more information.

'grep --help' is u friend !

syg00 · 08-17-2018, 05:50 AM

My first reaction was "read the manpage".

Code:

-v, --invert-match
              Invert the sense of matching, to select non-matching lines.

Now I see that "invert" may be causing confusion. The important bit is "to select non-matching lines."
grep normally returns matching lines, this is the inverse. Nothing to do with inverting (reverse sorting) the results.

Madhu Desai · 08-17-2018, 06:24 AM

Quote:

Originally Posted by sigint-ninja

does this command include or exclude comments starting with #
and sort them in reverse?

It excludes any line which has # in its line. Not just at the beginning.

To exclude # that is at the beginning, use

Code:

grep -v '^#'

sigint-ninja · 08-21-2018, 04:20 PM

thanks all