X-Recipient: archive-cygwin@delorie.com X-SWARE-Spam-Status: No, hits=-6.8 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Message-ID: <4D8D0CD4.50809@redhat.com> Date: Fri, 25 Mar 2011 15:44:52 -0600 From: Eric Blake User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.15) Gecko/20110307 Fedora/3.1.9-0.39.b3pre.fc14 Lightning/1.0b3pre Mnenhy/0.8.3 Thunderbird/3.1.9 MIME-Version: 1.0 To: cygwin@cygwin.com Subject: Re: IFS not fixing carriage returns References: In-Reply-To: OpenPGP: url=http://people.redhat.com/eblake/eblake.gpg Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------enig6CDE8BFBD9FB2103A591CD29" X-IsSubscribed: yes Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com --------------enig6CDE8BFBD9FB2103A591CD29 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 03/25/2011 10:35 AM, Tim McDaniel wrote: > Although it's not documented in "man bash" on the latest Cygwin, I did > find "set -o igncr" and it seems to work well. I documented it in the cygwin bash release notes, so it is in /usr/share/doc/Cygwin/bash.README. Patches welcome if you want to see it somewhere else like the man page, because that takes more effort. >=20 > But I'm just curious about why my first attempt didn't work. IFS only affects word splitting _after words have been parsed and expansions performed_. Bash does _not_ ignore CR in the input stream while parsing words, regardless of the IFS settings. Let's use a simpler example: If you set IFS=3D., then echo a.b will still only echo the one word "a.b" and not split into two words "a" and "b", because '.' is not special in determining word boundaries (a.b is a single word), and there was no expansion going on. And it would be prohibitively expensive to make shells honor random IFS while parsing out words, so bash _only_ uses space, tab, and newline to determine word boundaries, not carriage return. That's why igncr is more powerful than IFS - it strips the CR prior to the point that bash is even trying to parse the line into words. --=20 Eric Blake eblake@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org --------------enig6CDE8BFBD9FB2103A591CD29 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBCAAGBQJNjQzUAAoJEKeha0olJ0Nq484H/0LZAb2Qw8spkq/co2Bwokjx R4v3oE2hAisS+ZXIMAqt2gBuaQ9xA00q2uqi/4hO6m88mizjAXU7qO4WBPRf8ZIo EnJqu+hq9pLUQ7qIq8a9H9FhgI1M+XGRWASyK/gwNSPh2ubJrAPNEa2mDGuhuef3 dWsk0TDOd2Og9VFYbA3Ci5rg3oDhHnO5d7ye1NBLaBsohyMGRRpGND8w5VsPKnIz nGzOAjnkUTJKib+l0JoxAA3MQz9bl3xbv+SYbuOohBrvu9z6HFemoC14nzYcJ447 MeWYyVG22OD/pYnxN74dHDWAvY9rUapF7C51RjVsCKg8FRNx/YYYHVCkeg233a4= =ljF9 -----END PGP SIGNATURE----- --------------enig6CDE8BFBD9FB2103A591CD29--