Re: exit status in man page

[Matthew Woehlke]

Brent Barker wrote:
> my man page (1) for "grep" states:
>
>       Normally, exit status is 0 if selected lines are found and 1 
> otherwise.
>       But the exit status is 2 if an error occurred, unless the -q or 
> --quiet
>       or --silent option is used and a selected line is found.
>
>
> I'm using grep in a script, found here:
>
> #!/bin/bash
> if echo "$1" | grep /
> then
>  echo "returned 1"
> else
>  echo "returned 0"
> fi
>
> It seems that grep returns 1 if it finds the pattern, 0 if it does
> not. This seems to be contrary to what is said in the man page. The
> behavior is the same if I add the -q option.

Your assumptions are wrong. 0 is considered "success", anything else is 
considered failure. So your script above will echo "returned 1" when 
grep actually returns 0, and will echo "returned 0" when grep returns 
anything other than 0. Try this instead:

echo "$1" | grep / ; echo "returned $?"

This will display the actual return value, be it 0, 1, 2, 67*, or any 
other number. (*I don't think grep ever returns 67 :-). But some other 
program might.)

--
Matthew
Obscurity: +5