Date: Sun, 5 Oct 2003 17:43:14 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Dan Langille <dan@langille.org> Cc: freebsd-hackers@freebsd.org Subject: Re: testing for substrings in perl Message-ID: <20031005164314.GA60739@happy-idiot-talk.infracaninophile.co.uk> In-Reply-To: <20031005111656.R18760@xeon.unixathome.org> References: <20031005111656.R18760@xeon.unixathome.org>
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On Sun, Oct 05, 2003 at 11:32:11AM -0400, Dan Langille wrote:
> Hi,
>=20
> I have a perl regex to test if a file resides under a particular
> directory. The test looks like this:
>=20
> if ($filename =3D~ $directory) {
> # yes, this filename resides under directory
> }
>=20
> This is working for most cases. However, it fails is the directory
> contains a +. For example:
>=20
> $filename =3D 'ports/www/privoxy+ipv6/files/patch-src::addrlist.c';
>=20
> $match =3D "^/?" . 'ports/www/privoxy+ipv6' . "/";
> if ($filename =3D~ $match) {
> print "found\n";
> } else{
> print "NOT found\n";
> }
>=20
> Yes, I can escapte the + in the directory name, but then I'd have to test
> for all those special regex characters and escape them too.
That's why perl has the \Q...\E metasymbols:
Try:
$match =3D qr{^/?\Q$dirname\E/};
See perldoc perlre for details.
Cheers,
Matthew
=09
--=20
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
Savill Way
PGP: http://www.infracaninophile.co.uk/pgpkey Marlow
Tel: +44 1628 476614 Bucks., SL7 1TH UK
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