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Date: Mon, 10 Jun 2013 12:22:35 -0700
Message-ID: <CAHu1Y70FNX8G2ARF5zBzRbu5iMsXVkUCouBk-YruY3xH1gWsqg@mail.gmail.com>
Subject: Re: Bourne shell "if" syntax
From: Michael Sierchio <kudzu@tenebras.com>
To: FreeBSD Questions <freebsd-questions@freebsd.org>
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On Mon, Jun 10, 2013 at 12:16 PM, Tim Daneliuk <tundra@tundraware.com> wrote:

> That wasn't really my point.  I use sentinels because in the face of an
> empty string this:
>
>    if [ $PTR = "" ]
>
> Actually evaluates to:
>
>    if [ = "" ]
>
> Which throws an error.

Right.  Many scripts seem to assume that sh is bash, and that's
certainly not the case here.

if [ "x$BLAH" = "x" ]; then

is the most reliable and portable way of determining if it's a string
of zero length.

- M