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Bzip2 Howto David Fetter, dfetter@best.com <mailto:dfetter@best.com> v1.92, 18 August 1998 This document tells how to use the new bzip2 compression program. The local copy of the sgml at the current site is here <Bzip2-HOWTO.sgml>, and the "author-itative" sgml is here <http://www.best.com/~dfet¡ ter/Bzip2-HOWTO/Bzip2-HOWTO.sgml>. ______________________________________________________________________ Table of Contents 1. Introduction 1.1 (BF 1.1.1 v1.92 Updated the 1.1.2 v1.91 1.1.3 v1.9 1.1.4 v1.8 1.1.5 v1.7 1.1.6 v1.6 1.1.7 v1.5 1.1.8 v1.4 1.1.9 v1.3 1.1.10 v1.2 1.1.11 v1.1 1.1.12 v1.0 2. Getting bzip2 2.1 Bzip2-HOWTO in your language 2.2 Getting bzip2 precompiled binaries 2.3 Getting bzip2 sources 2.4 Compiling bzip2 for your machine 3. Using bzip2 by itself 4. Using bzip2 with tar 4.1 Easiest to set up: 4.2 Easy to set up, fairly easy to use, no need for root privileges: 4.3 Also easy to use, but needs root access. 5. Using bzip2 with less 6. Using bzip2 with emacs 6.1 Changing emacs for everyone: 6.2 Changing emacs for one person: 7. Using bzip2 with wu-ftpd 8. Using bzip2 with grep 9. Using bzip2 with Netscape under the X. 10. Using bzip2 to recompress other compression formats ______________________________________________________________________ 1. Introduction Bzip2 is a groovy new algorithm for compressing data. It generally makes files that are 60-70% of the size of their gzip'd counterparts. This document will take you through a few common applications for bzip2. Future versions of the document will discuss the upcoming bzip2 library which bzip2's author, Julian Seward <mailto:Julian_Seward@muraroa.demon.co.uk> describes as follows: I'm working on the next version of bzip2, which will use the same .bz2 file format; the main addition is a zlib-like library for reading and writing data in that format from within programs. Future versions of the document may also include a summary of the discussion over whether (and how) bzip2 should be used in the Linux kernel. 1.1. Revision History 1.1.1. Updated the``Getting bzip2 binaries'' section, including adding S.u.S.E.'s. v1.92 1.1.2. v1.91 Corrected a typo and clarified some shell idioms in the ``section on using bzip2 with tar''. Thanks to Alessandro Rubini for these. Updated the buzzit tool not to stomp on the original bzip2 archive. Added bgrep, a zgrep-like tool. 1.1.3. v1.9 Clarified the gcc 2.7.* problem. Thanks to Ulrik Dickow for pointing this out. Added Leonard Jean-Marc's elegant way to work with tar. Added Linus ├kerlund's Swedish translation. Fixed the wu-ftpd section per Arnaud Launay's suggestion. Moved translations to their own section. 1.1.4. v1.8 Put buzzit and tar.diff in the sgml where they belong. Fixed punctuation and formatting. Thanks to Arnaud Launay for his help correcting my copy. :-) Dropped xv project for now due to lack of popular interest. Added teasers for future versions of the document. 1.1.5. v1.7 Added buzzit utility. Fixed the patch against gnu tar. 1.1.6. v1.6 Added TenThumbs' Netscape enabler. Also changed lesspipe.sh per his sugestion. It should work better now. 1.1.7. v1.5 Added Arnaud Launay's French translation, and his wu-ftpd file. 1.1.8. v1.4 Added Tetsu Isaji's Japanese translation. 1.1.9. v1.3 Added Ulrik Dickow's .emacs for 19.30 and higher. (Also corrected jka-compr.el patch for emacs per his suggestion. Oops! Bzip2's doesn't yet(?) have an "append" flag.) 1.1.10. v1.2 Changed patch for emacs so it automagically recognizes .bz2 files. 1.1.11. v1.1 Added patch for emacs. 1.1.12. v1.0 Round 1. 2. Getting bzip2 Bzip2's home page is at The UK home site <http://www.muraroa.demon.co.uk/>. The United States mirror site is here <http://www.digistar.com/bzip2/index.html>. You can also find it on Red Hat's ftp site here <ftp://ftp.redhat.com/pub/contrib>. 2.1. Bzip2-HOWTO in your language French speakers may wish to refer to Arnaud Launay's French documents. The web version is here <http://www.freenix.fr/linux/HOWTO/mini/Bzip2.html>, and you can use ftp here <ftp://ftp.lip6.fr/pub/linux/french/docs/HOWTO/mini/Bzip2.gz> Arnaud can be contacted by electronic mail at this address <mailto:zoro@mygale.org> Japanese speakers may wish to refer to Tetsu Isaji's Japanese documents here <http://jf.gee.kyoto-u.ac.jp/JF/JF.html>. Isaji can be reached at his home page <http://www2s.biglobe.ne.jp/~kaien/>, or by electronic mail at this address. <mailto:isaji@mxu.meshnet.or.jp> Swedish speakers may wish to refer to Linus ├kerlund's Swedish documents here <http://user.tninet.se/~uxm165t/linux_doc.html>. Linus can be reached by electronic mail at this address. <mailto:uxm165t@tninet.se> 2.2. Getting bzip2 precompiled binaries See the home sites. Debian's Intel binary is <ftp://ftp.debian.org/debian/dists/stable/main/binary- i386/utils/bzip2_0.1pl2-5.deb name=>>. Red Hat's alpha binary is here <ftp://ftp.redhat.com/pub/redhat/redhat-5.1/alpha/RedHat/RPMS/bzip2-0.1pl2-1.alpha.rpm>. Red Hat's Intel binary is here <ftp://ftp.redhat.com/pub/redhat/redhat-5.1/i386/RedHat/RPMS/bzip2-0.1pl2-1.i386.rpm>. Red Hat's SPARC binary is here <ftp://ftp.redhat.com/pub/redhat/redhat-5.1/sparc/RedHat/RPMS/bzip2-0.1pl2-1.sparc.rpm>. Slackware's Intel binary is here <ftp://www.cdrom.com/pub/linux/slackware-3.5/slakware/a1/bzip2.tgz>. S.u.S.E.'s Intel binary is here <ftp://ftp.suse.com/pub/SuSE- Linux/5.2/suse/ap1/bzip.rpm>. You can also get these in the analogous places at the various mirror sites. 2.3. Getting bzip2 sources They come from the Official sites (see ``Getting Bzip2'' for where, or Red Hat has it here <ftp://ftp.redhat.com/pub/contrib/SRPMS/bzip2-0.1pl2-1.src.rpm>). 2.4. Compiling bzip2 for your machine If you have gcc 2.7.*, change the line that reads CFLAGS = -O3 -fomit-frame-pointer -funroll-loops to CFLAGS = -O2 -fomit-frame-pointer that is, replace -O3 with -O2 and drop the -funroll-loops. You may also wish to add any -m* flags (like -m486, for example) you use when compiling kernels. Avoiding -funroll-loops is the most important part, since this will cause many gcc 2.7's to generate wrong code, and all gcc 2.7's to generate slower and larger code. For other compilers (lcc, egcs, gcc 2.8.x) the default CFLAGS are fine. After that, just make it and install it per the README. 3. Using bzip2 by itself Read the Fine Manual Page :) 4. Using bzip2 with tar Listed below are three ways to use bzip2 with tar, namely 4.1. Easiest to set up: This method requires no setup at all. To un-tar the bzip2'd tar archive, foo.tar.bz2 in the current directory, do /path/to/bzip2 -cd foo.tar.bz2 | tar xf - This works, but can be a PITA to type often. 4.2. Easy to set up, fairly easy to use, no need for root privileges: Thanks to Leonard Jean-Marc <mailto:leonard@sct1.is.belgacom.be> for the tip. Thanks also to Alessandro Rubini <mailto:rubini@morgana.systemy.it> for differentiating bash from the csh's. In your .bashrc, you can put in a line like this: alias btar='tar --use-compress-program /usr/local/bin/bzip2 ' In your .tcshrc, or .cshrc, the analogous line looks like this: alias btar 'tar --use-compress-program /usr/local/bin/bzip2' 4.3. Also easy to use, but needs root access. Apply the patch below to gnu tar 1.12 as follows: cd tar-1.12/src; patch < /path/to/tar.diff compile it, and install it, and you're good to go. Make sure that both tar and bzip2 are in your $PATH by "which tar" and "which bzip2." To use the new tar, just do tar xyf foo.tar.bz2 to decompress the file. To make a new archive, it's similar: tar cyf foo.tar.bz2 file1 file2 file3...directory1 directory2... Here is the patch: *** tar.c Thu Jun 11 00:09:23 1998 --- tar.c.new Thu Jun 11 00:14:24 1998 *************** *** 196,201 **** --- 196,203 ---- {"block-number", no_argument, NULL, 'R'}, {"block-size", required_argument, NULL, OBSOLETE_BLOCKING_FACTOR}, {"blocking-factor", required_argument, NULL, 'b'}, + {"bzip2", required_argument, NULL, 'y'}, + {"bunzip2", required_argument, NULL, 'y'}, {"catenate", no_argument, NULL, 'A'}, {"checkpoint", no_argument, _option, 1}, {"compare", no_argument, NULL, 'd'}, *************** *** 372,377 **** --- 374,380 ---- PATTERN at list/extract time, a globbing PATTERN\n\ -o, --old-archive, --portability write a V7 format archive\n\ --posix write a POSIX conformant archive\n\ + -y, --bzip2, --bunzip2 filter the archive through bzip2\n\ -z, --gzip, --ungzip filter the archive through gzip\n\ -Z, --compress, --uncompress filter the archive through compress\n\ --use-compress-program=PROG filter through PROG (must accept -d)\n"), *************** *** 448,454 **** Y per-block gzip compression */ #define OPTION_STRING \ ! "-01234567ABC:F:GK:L:MN:OPRST:UV:WX:Zb:cdf:g:hiklmoprstuvwxz" static void set_subcommand_option (enum subcommand subcommand) --- 451,457 ---- Y per-block gzip compression */ #define OPTION_STRING \ ! "-01234567ABC:F:GK:L:MN:OPRST:UV:WX:Zb:cdf:g:hiklmoprstuvwxyz" static void set_subcommand_option (enum subcommand subcommand) *************** *** 805,810 **** --- 808,817 ---- case 'X': exclude_option = 1; add_exclude_file (optarg); + break; + + case 'y': + set_use_compress_program_option ("bzip2"); break; case 'z': 5. Using bzip2 with less To uncompress bzip2'd files on the fly, i.e. to be able to use "less" on them without first bunzip2'ing them, you can make a lesspipe.sh (man less) like this: #!/bin/sh # This is a preprocessor for 'less'. It is used when this environment # variable is set: LESSOPEN="|lesspipe.sh %s" case "$1" in *.tar) tar tvvf $1 2>/dev/null ;; # View contents of various tar'd files *.tgz) tar tzvvf $1 2>/dev/null ;; # This one work for the unmodified version of tar: *.tar.bz2) bzip2 -cd $1 $1 2>/dev/null | tar tzvvf - ;; #This one works with the patched version of tar: # *.tar.bz2) tyvvf $1 2>/dev/null ;; *.tar.gz) tar tzvvf $1 2>/dev/null ;; *.tar.Z) tar tzvvf $1 2>/dev/null ;; *.tar.z) tar tzvvf $1 2>/dev/null ;; *.bz2) bzip2 -dc $1 2>/dev/null ;; # View compressed files correctly *.Z) gzip -dc $1 2>/dev/null ;; *.z) gzip -dc $1 2>/dev/null ;; *.gz) gzip -dc $1 2>/dev/null ;; *.zip) unzip -l $1 2>/dev/null ;; *.1|*.2|*.3|*.4|*.5|*.6|*.7|*.8|*.9|*.n|*.man) FILE=`file -L $1` ; # groff src FILE=`echo $FILE | cut -d ' ' -f 2` if [ "$FILE" = "troff" ]; then groff -s -p -t -e -Tascii -mandoc $1 fi ;; *) cat $1 2>/dev/null ;; # *) FILE=`file -L $1` ; # Check to see if binary, if so -- view with 'strings' # FILE1=`echo $FILE | cut -d ' ' -f 2` # FILE2=`echo $FILE | cut -d ' ' -f 3` # if [ "$FILE1" = "Linux/i386" -o "$FILE2" = "Linux/i386" \ # -o "$FILE1" = "ELF" -o "$FILE2" = "ELF" ]; then # strings $1 # fi ;; esac 6. Using bzip2 with emacs 6.1. Changing emacs for everyone: I've written the following patch to jka-compr.el which adds bzip2 to auto-compression-mode. Disclaimer: I have only tested this with emacs-20.2, but have no reason to believe that a similar approach won't work with other versions. To use it, 1. Go to the emacs-20.2/lisp source directory (wherever you untarred it) 2. Put the patch below in a file called jka-compr.el.diff (it should be alone in that file ;). 3. Do patch < jka-compr.el.diff 4. Start emacs, and do M-x byte-compile-file jka-compr.el 5. Leave emacs. 6. Move your original jka-compr.elc to a safe place in case of bugs. 7. Replace it with the new jka-compr.elc. 8. Have fun! --- jka-compr.el Sat Jul 26 17:02:39 1997 +++ jka-compr.el.new Thu Feb 5 17:44:35 1998 @@ -44,7 +44,7 @@ ;; The variable, jka-compr-compression-info-list can be used to ;; customize jka-compr to work with other compression programs. ;; The default value of this variable allows jka-compr to work with -;; Unix compress and gzip. +;; Unix compress and gzip. David Fetter added bzip2 support :) ;; ;; If you are concerned about the stderr output of gzip and other ;; compression/decompression programs showing up in your buffers, you @@ -121,7 +121,9 @@ ;;; I have this defined so that .Z files are assumed to be in unix -;;; compress format; and .gz files, in gzip format. +;;; compress format; and .gz files, in gzip format, and .bz2 files, +;;; in the snappy new bzip2 format from http://www.muraroa.demon.co.uk. +;;; Keep up the good work, people! (defcustom jka-compr-compression-info-list ;;[regexp ;; compr-message compr-prog compr-args @@ -131,6 +133,10 @@ "compressing" "compress" ("-c") "uncompressing" "uncompress" ("-c") nil t] + ["\\.bz2\\'" + "bzip2ing" "bzip2" ("") + "bunzip2ing" "bzip2" ("-d") + nil t] ["\\.tgz\\'" "zipping" "gzip" ("-c" "-q") "unzipping" "gzip" ("-c" "-q" "-d") 6.2. Changing emacs for one person: Thanks for this one go to Ulrik Dickow, ukd@kampsax.dk <mailto:ukdATkampsax.dk>, Systems Programmer at Kampsax Technology: To make it so you can use bzip2 automatically when you aren't the sysadmin, just add the following to your .emacs file. ;; Automatic (un)compression on loading/saving files (gzip(1) and similar) ;; We start it in the off state, so that bzip2(1) support can be added. ;; Code thrown together by Ulrik Dickow for ~/.emacs with Emacs 19.34. ;; Should work with many older and newer Emacsen too. No warranty though. ;; (if (fboundp 'auto-compression-mode) ; Emacs 19.30+ (auto-compression-mode 0) (require 'jka-compr) (toggle-auto-compression 0)) ;; Now add bzip2 support and turn auto compression back on. (add-to-list 'jka-compr-compression-info-list ["\\.bz2\$~\\|\\.~[0-9]+~\$?\\'" "zipping" "bzip2" () "unzipping" "bzip2" ("-d") nil t]) (toggle-auto-compression 1 t) 7. Using bzip2 with wu-ftpd Thanks to Arnaud Launay for this bandwidth saver. The following should go in /etc/ftpconversions to do on-the-fly compressions and decompressions with bzip2. Make sure that the paths (like /bin/compress) are right. :.Z: : :/bin/compress -d -c %s:T_REG|T_ASCII:O_UNCOMPRESS:UNCOMPRESS : : :.Z:/bin/compress -c %s:T_REG:O_COMPRESS:COMPRESS :.gz: : :/bin/gzip -cd %s:T_REG|T_ASCII:O_UNCOMPRESS:GUNZIP : : :.gz:/bin/gzip -9 -c %s:T_REG:O_COMPRESS:GZIP :.bz2: : :/bin/bzip2 -cd %s:T_REG|T_ASCII:O_UNCOMPRESS:BUNZIP2 : : :.bz2:/bin/bzip2 -9 -c %s:T_REG:O_COMPRESS:BZIP2 : : :.tar:/bin/tar -c -f - %s:T_REG|T_DIR:O_TAR:TAR : : :.tar.Z:/bin/tar -c -Z -f - %s:T_REG|T_DIR:O_COMPRESS|O_TAR:TAR+COMPRESS : : :.tar.gz:/bin/tar -c -z -f - %s:T_REG|T_DIR:O_COMPRESS|O_TAR:TAR+GZIP : : :.tar.bz2:/bin/tar -c -y -f - %s:T_REG|T_DIR:O_COMPRESS|O_TAR:TAR+BZIP2 8. Using bzip2 with grep The following utility, which I call bgrep, is a slight modification of the zgrep which comes with Linux. You can use it to grep through files without bunzip2'ing them first. #!/bin/sh # bgrep -- a wrapper around a grep program that decompresses files as needed PATH="/usr/bin:$PATH"; export PATH prog=`echo $0 | sed 's|.*/||'` case "$prog" in *egrep) grep=${EGREP-egrep} ;; *fgrep) grep=${FGREP-fgrep} ;; *) grep=${GREP-grep} ;; esac pat="" while test $# -ne 0; do case "$1" in -e | -f) opt="$opt $1"; shift; pat="$1" if test "$grep" = grep; then # grep is buggy with -e on SVR4 grep=egrep fi;; -*) opt="$opt $1";; *) if test -z "$pat"; then pat="$1" else break; fi;; esac shift done if test -z "$pat"; then echo "grep through bzip2 files" echo "usage: $prog [grep_options] pattern [files]" exit 1 fi list=0 silent=0 op=`echo "$opt" | sed -e 's/ //g' -e 's/-//g'` case "$op" in *l*) list=1 esac case "$op" in *h*) silent=1 esac if test $# -eq 0; then bzip2 -cd | $grep $opt "$pat" exit $? fi res=0 for i do if test $list -eq 1; then bzip2 -cdfq "$i" | $grep $opt "$pat" > /dev/null && echo $i r=$? elif test $# -eq 1 -o $silent -eq 1; then bzip2 -cd "$i" | $grep $opt "$pat" r=$? else bzip2 -cd "$i" | $grep $opt "$pat" | sed "s|^|${i}:|" r=$? fi test "$r" -ne 0 && res="$r" done exit $res 9. Using bzip2 with Netscape under the X. tenthumbs@cybernex.net says: I also found a way to get Linux Netscape to use bzip2 for Content- Encoding just as it uses gzip. Add this to $HOME/.Xdefaults or $HOME/.Xresources I use the -s option because I would rather trade some decompressing speed for RAM usage. You can leave the option out if you want to. Netscape*encodingFilters: \ x-compress : : .Z : uncompress -c \n\ compress : : .Z : uncompress -c \n\ x-gzip : : .z,.gz : gzip -cdq \n\ gzip : : .z,.gz : gzip -cdq \n\ x-bzip2 : : .bz2 : bzip2 -ds \n 10. Using bzip2 to recompress other compression formats The following perl program takes files compressed in other formats (.tar.gz, .tgz. .tar.Z, and .Z for this iteration) and repacks them for better compression. The perl source has all kinds of neat documentation on what it does and how it does what it does. #!/usr/bin/perl -w ####################################################### # # # This program takes compressed and gzipped programs # # in the current directory and turns them into bzip2 # # format. It handles the .tgz extension in a # # reasonable way, producing a .tar.bz2 file. # # # ####################################################### $counter = 0; $saved_bytes = 0; $totals_file = '/tmp/machine_bzip2_total'; $machine_bzip2_total = 0; while(<*[Zz]>) { next if /^bzip2-0.1pl2.tar.gz$/; push @files, $_; } $total = scalar(@files); foreach (@files) { if (/tgz$/) { ($new=$_) =~ s/tgz$/tar.bz2/; } else { ($new=$_) =~ s/\.g?z$/.bz2/i; } $orig_size = (stat $_)[7]; ++$counter; print "Repacking $_ ($counter/$total)...\n"; if ((system "gzip -cd $_ |bzip2 >$new") == 0) { $new_size = (stat $new)[7]; $factor = int(100*$new_size/$orig_size+.5); $saved_bytes += $orig_size-$new_size; print "$new is about $factor% of the size of $_. :",($factor<100)?')':'(',"\n"; unlink $_; } else { print "Arrgghh! Something happened to $_: $!\n"; } } print "You've ", ($saved_bytes>=0)?"saved":"lost", " $saved_bytes bytes of storage space :", ($saved_bytes>=0)?")":"(", "\n"; unless (-e '/tmp/machine_bzip2_total') { system ('echo "0" >/tmp/machine_bzip2_total'); system ('chmod', '0666', '/tmp/machine_bzip2_total'); } chomp($machine_bzip2_total = `cat $totals_file`); open TOTAL, ">$totals_file" or die "Can't open system-wide total: $!"; $machine_bzip2_total += $saved_bytes; print TOTAL $machine_bzip2_total; close TOTAL; print "That's a machine-wide total of ",`cat $totals_file`," bytes saved.\n";