The following command produces matches. # egrep ^[\[].+[\]] /var/log/apache2/error.log However, if I save the pattern to a file and use the -f option, it produces no matches. I have to change the pattern to this: ^[\[].+\] Notice I had to remove the enclosing square brackets to get the literal closing bracket to match when using the -f option. This is on a Debian Squeeze system. Below is the package information. I am happy to provide more details if you needed. # apt-cache show grep Package: grep Essential: yes Priority: required Section: utils Installed-Size: 1148 Maintainer: Anibal Monsalve Salazar Architecture: amd64 Version: 2.6.3-3+squeeze1 Provides: rgrep Depends: dpkg (>= 1.15.4) | install-info Pre-Depends: libc6 (>= 2.3) Suggests: libpcre3 (>= 7.7) Conflicts: rgrep Filename: pool/main/g/grep/grep_2.6.3-3+squeeze1_amd64.deb Size: 313920 MD5sum: 7c8b301e28fc614cd99b04ea87ad0fee SHA1: 7ebde8d23c4efe40d6744ec9f79133c37b7d2150 SHA256: e0bb207f1446f5b560540df30cee048fe623b5de164c5e035323cffb59de1736 Description: GNU grep, egrep and fgrep 'grep' is a utility to search for text in files; it can be used from the command line or in scripts. Even if you don't want to use it, other packages on your system probably will. . The GNU family of grep utilities may be the "fastest grep in the west". GNU grep is based on a fast lazy-state deterministic matcher (about twice as fast as stock Unix egrep) hybridized with a Boyer-Moore-Gosper search for a fixed string that eliminates impossible text from being considered by the full regexp matcher without necessarily having to look at every character. The result is typically many times faster than Unix grep or egrep. (Regular expressions containing backreferencing will run more slowly, however.) Homepage: http://www.gnu.org/software/grep/ Tag: implemented-in::c, interface::commandline, role::program, scope::utility, suite::gnu, use::searchin Package: grep Essential: yes Status: install ok installed Priority: required Section: utils Installed-Size: 768 Maintainer: Anibal Monsalve Salazar Architecture: amd64 Version: 2.6.3-3 Provides: rgrep Depends: dpkg (>= 1.15.4) | install-info Pre-Depends: libc6 (>= 2.3) Suggests: libpcre3 (>= 7.7) Conflicts: rgrep Description: GNU grep, egrep and fgrep 'grep' is a utility to search for text in files; it can be used from the command line or in scripts. Even if you don't want to use it, other packages on your system probably will. . The GNU family of grep utilities may be the "fastest grep in the west". GNU grep is based on a fast lazy-state deterministic matcher (about twice as fast as stock Unix egrep) hybridized with a Boyer-Moore-Gosper search for a fixed string that eliminates impossible text from being considered by the full regexp matcher without necessarily having to look at every character. The result is typically many times faster than Unix grep or egrep. (Regular expressions containing backreferencing will run more slowly, however.) Homepage: http://www.gnu.org/software/grep/ Aaron Selk Information Services 4910 Burlington Way Tacoma, WA 98409 Ph: 253.473.5000 Fax: 253.473.5104 www.generalplastics.com [emailsig-logo] [facebook_resized] [twitter_resized] [linkedin_resized] [youtube_resized] The contents of this electronic message and any attachments are considered confidential and are intended only for the use of the individual or entity identified above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this e-mail in error, please notify the sender and delete this message, as well as any attachments.