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From: dave@csu60.UUCP
Newsgroups: net.unix-wizards
Subject: Re: Why parse lines with colons
Message-ID: <25@csu60.OZ>
Date: Fri, 13-Jul-84 11:09:28 EDT
Article-I.D.: csu60.25
Posted: Fri Jul 13 11:09:28 1984
Date-Received: Thu, 19-Jul-84 02:28:30 EDT
References: <526@spuxll.UUCP>
Organization: CSU, Uni of NSW, Sydney, Australia
Lines: 12

Maybe my shell is weird, but I had to say:

FOO=${FOO:-default}

The simple ": ${FOO:-default}" didn't work.

I find those ":" comments useful for makefiles where I want to
null out a particular operation e.g.

INSTALL=":" make fred

where $INSTALL normally defaults to "install".