Date: Mon, 04 Feb 2002 12:25:30 -0330 From: Paul David Fardy <pdf@morgan.ucs.mun.ca> To: cjclark@alum.mit.edu Cc: questions@FreeBSD.org Subject: Re: Perl question... Message-ID: <200202041555.g14FtVSU004141@plato.ucs.mun.ca> In-Reply-To: Your message of "Fri, 01 Feb 2002 15:22:07 PST." <20020201152207.C956@gohan.cjclark.org>
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On Fri, Feb 01, 2002 at 05:24:46PM -0330, Paul David Fardy wrote:
>> I've been using Perl so much, I've forgotten some of my shell rules.
>> I tested this code because I thought "$TTL" would result in the
>> expansion of an undefined variable TTL. In Perl, it _would_ be a
>> problem. In sh, it's fine.
Your message dated: Fri, 01 Feb 2002 15:22:07 PST
> It is not expanded because I quoted "EOF" as the here-doc
> delimiter. If I had not, it would have been.
>> ed $file <<"EOF"
Yeah, I realize that (now). I was just noting the re-wiring of my
brain to follow Perl's rules wherein the expansion of a here-doc is
enabled by
<<"EOF"
and disabled by
<<'EOF'
This should probably have been just my "note-to-self". But I figure
it has enough educational value under the subject ("Perl question")
that others might learn from it.
1) Perl and the shells have a useful feature called "here documents";
2) one needs to be careful about the expansion of variables within a
here-doc (irrespective of which language you use); and
3) the Perl and shell rules for here docs differ in significant ways.
Paul
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