Re: grep raises signal ERR

[Eric Blake <ebb9 at byu dot net>]

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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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