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Sun, 10 Sep 2006 23:45:16 +0200
On Sun, Sep 10, 2006 at 03:32:25PM -0600, Philip Guenther wrote:
> On 9/10/06, Louis-David Mitterrand <address@hidden>
> >I'm trying to get this rule to work:
> > id3tag:
> > echo mp3/blues/john_lee_hooker/boom_boom/ | IFS=/ read
> > form genre artist album && echo "$$form $$genre $$artist
> > $$album"
> >but it echoes nothing.
> Normally, the various commands in a pipeline are all executed in
> separate processes. Some shells will handle the last command of the
> pipeline in the original process if it's a 'read', but last I checked
> that was not required by the POSIX standard.
Yes, zsh behaves that way.
> So, it appears that the shell used by make by default (/bin/sh)
> doesn't do that special handling. There are a number of workaround,
> the simplest being to make the 'last command of the pipeline' contain
> not just the 'read' but also the commands that need the variable
> values. That can be done by grouping them into a subshell with
> echo mp3/blues/john_lee_hooker/boom_boom/ | \
> ( IFS=/ read form genre artist album && \
> echo "$$form $$genre $$artist $$album" )
This works fine!
> >When issued from a shell it works.
> Apparently your login shell performs that special handling, at least
> when used interactively.
Thanks for your helpful and detailed explanation.
- shell, Louis-David Mitterrand, 2006/09/10
- Re: shell, Philip Guenther, 2006/09/10
- Re: shell,
Louis-David Mitterrand <=
- Message not available