I'm trying to do a diff on MySQL dumps (created with mysqldump and piped to bzip2), to see if there are changes between consecutive dumps. The followings are the tails of 2 dumps: tmp1: /*!40101 SET SQL_MODE=@OLD_SQL_MODE */; /*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */; /*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */; /*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */; /*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */; /*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */; /*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */; -- Dump completed on 2011-03-11 1:06:50 tmp2: /*!40101 SET SQL_MODE=@OLD_SQL_MODE */; /*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */; /*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */; /*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */; /*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */; /*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */; /*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */; -- Dump completed on 2011-03-11 0:40:11 When I bzdiff their bzipped version: $ bzdiff tmp?.bz2 10c10 < -- Dump completed on 2011-03-11 1:06:50 --- > -- Dump completed on 2011-03-11 0:40:11 According to the manual of bzdiff, any option passed on to bzdiff is passed on to diff. I therefore looked at the -I option that allows to define a regexp; lines matching it are ignored in the diff. When I then try: $ bzdiff -I'Dump' tmp1.bz2 tmp2.bz2 I get an empty diff. I would like to match as much as possible of the "Dump completed" line, though, but when I then try: $ bzdiff -I'Dump completed' tmp1.bz2 tmp2.bz2 diff: extra operand `/tmp/bzdiff.miCJEvX9E8' diff: Try `diff --help' for more information. Same thing happens for some variations: $ bzdiff '-IDump completed' tmp1.bz2 tmp2.bz2 $ bzdiff '-I"Dump completed"' tmp1.bz2 tmp2.bz2 $ bzdiff -'"IDump completed"' tmp1.bz2 tmp2.bz2 If I diff the un-bzipped files there is no problem: $diff -I'^[-][-] Dump completed on' tmp1 tmp2 gives also an empty diff. bzdiff is a shell script usually placed in /bin/bzdiff. Essentially, it parses the command options and passes them on to diff as follows: OPTIONS= FILES= for ARG do case "$ARG" in -*) OPTIONS="$OPTIONS $ARG";; *) if test -f "$ARG"; then FILES="$FILES $ARG" else echo "${prog}: $ARG not found or not a regular file" exit 1 fi ;; esac done [...] bzip2 -cdfq "$1" | $comp $OPTIONS - "$tmp" I think the problem stems from escaping the spaces in the passing of $OPTIONS to diff, but I couldn't figure out how to get it interpreted correctly. Any ideas? EDIT @DerfK: Good point with the ., I had forgotten about them... I tried the suggestion with the multiple level of quotes, but that is still not recognized: $ bzdiff "-I'\"Dump.completed.on\"'" tmp1.bz2 tmp2.bz2 diff: extra operand `/tmp/bzdiff.Di7RtihGGL'