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Re: grep raises signal ERR
- From: Eric Blake <ebb9 at byu dot net>
- To: cygwin at cygwin dot com, arnstein at panix dot com
- Date: Wed, 14 May 2008 18:42:06 -0600
- Subject: Re: grep raises signal ERR
- References: <20080515003601.GA18386@panix.com>
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According to David Arnstein on 5/14/2008 6:36 PM:
| #!/bin/bash
| trap "echo '<aborting>' ; exit 1" ERR
| grep -q -e 'foo' < /dev/null
|
| This indicates that grep has raised the signal ERR.
There is no such thing as signal ERR. Rather, ERR is a special case to
the trap command that means the trap is executed when any simple command
returns non-zero status (in the same cases that set -e would cause the
shell to exit). 'man bash' explains this in more detail.
| grep -q -e 'foo' < /dev/null
| is NOT aborting my shell script. It simply returns status 1, which I
| do NOT want to handle by calling exit.
Then don't trap ERR, or else write your script to handle expected non-zero
status. For example,
~ grep -q -e 'foo' < /dev/null || :
is not a simple command (it uses ||), so it won't trigger the ERR trap nor
cause a 'set -e' shell to exit.
By the way, none of this is cygwin specific.
- --
Don't work too hard, make some time for fun as well!
Eric Blake ebb9@byu.net
volunteer cygwin bash maintainer
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