Date: Thu, 08 May 2014 18:24:04 -0400 From: monahbaki@gmail.com To: Rick Miller <vmiller@hostileadmin.com>, Polytropon <freebsd@edvax.de>, Erich Dollansky <erichsfreebsdlist@alogt.com> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: Bourne d unset outside while() Message-ID: <20140508222404.5898387.62898.7104@gmail.com> In-Reply-To: <CAHzLAVETmYjt6Az0q519v41g6RGmEV8A%2BAEC2fbZdBtM3wFAMw@mail.gmail.com> References: <CAHzLAVFhyPtkWCj1uj0aq0AusfrWL55UUn-mkxiyzUus7x4vdA@mail.gmail.com> <20140508225459.83f70b3c.freebsd@edvax.de> <CAHzLAVETmYjt6Az0q519v41g6RGmEV8A%2BAEC2fbZdBtM3wFAMw@mail.gmail.com>
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=A0 Original Message =A0
From: Rick Miller
Sent: Thursday, May 8, 2014 5:18 PM
To: Polytropon
Cc: FreeBSD Question ns
Subject: Re: Bourne variable unset outside while()
Thanks, Polytropon & Matthew!
On Thu, May 8, 2014 at 4:54 PM, Polytropon <freebsd@edvax.de> wrote:
>
> You have identified the problem: With the | redirector, a subshell
> is started which populates ${labels}, but at the "higher" level
> ${labels} keeps its setting (in this case, implicit empty string).
>
> Here's a workaround, using awk:
>
> #!/bin/sh
>
> fs=3D"freebsd-ufs gprootfs 1G
> freebsd-swap gpswapfs 1G
> freebsd-ufs gpvarfs 1G"
>
> labels=3D`echo "${fs}" | awk '{printf("%s ", $2);}'`
> echo "labels =3D ${labels}"
>
> In this example, with `...`, which is the same as $(...), also
> starts a subshell, but assigns its output to a variable, so there
> will be no scope problem. This idea uses the advantage that your
> delimiter is newline, and awk can process the input line per line,
> printing "incomplete lines" (no newline added) as output.
>
> The result will be:
>
> labels =3D gprootfs gpswapfs gpvarfs
>
> Is this what you expected?
>
Wow! It's soooo obvious to me now that you've pointed it out. I don't
often use while read's in this manner. Thanks for the feedback!
--=20
Take care
Rick Miller
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