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Re: grep: return code with -v and empty input
From: |
tt |
Subject: |
Re: grep: return code with -v and empty input |
Date: |
20 Mar 2001 20:58:26 +0200 |
address@hidden (Edward Avis) writes:
> According to the documentation, the -v flag is supposed to invert the
> exit status:
>
> >Normally, exit status is 0 if matches were found, and 1 if no matches
> >were found (the `-v' option inverts the sense of the exit status).
> However it doesn't seem to work like that for empty input.
> I suspect this may be a documentation bug; perhaps it should say
> something like:
>
> 'If the -v flag is given, then a "matching line" is one which does _not_
> match the pattern. The exit status is still 0 if there were no
> "matching lines" and 1 if there were some.'
That is indeed the way it is supposed to work according to POSIX.2:
"
-v Select lines not matching any of the specified patterns.
...
The grep utility shall exit with one of the following values:
0 One or more lines were selected.
1 No lines were selected.
>1 An error occurred.
"
Clarifying the documentation might be in order.
--
Tapani Tarvainen