98 lines
2.9 KiB
HTML
98 lines
2.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>Bzip2 mini-HOWTO: Using bzip2 to recompress other compression formats</TITLE>
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<LINK HREF="Bzip2-9.html" REL=previous>
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<LINK HREF="Bzip2.html#toc10" REL=contents>
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<BODY>
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<A HREF="Bzip2-9.html">Previous</A>
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<A HREF="Bzip2.html#toc10">Contents</A>
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<HR>
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<H2><A NAME="s10">10. Using bzip2 to recompress other compression formats</A></H2>
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<P>The following perl program takes files compressed
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in other formats (.tar.gz, .tgz. .tar.Z, and .Z for this iteration) and repacks
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them for better compression. The perl source has all kinds of neat
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documentation on what it does and how it does what it does. This latest
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version takes files as input on the command line. Without command line
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arguments, it tries to repack every file in the current working
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directory.
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<P>
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<PRE>
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#!/usr/bin/perl -w
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#######################################################
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# #
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# This program takes compressed and gzipped programs #
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# in the current directory and turns them into bzip2 #
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# format. It handles the .tgz extension in a #
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# reasonable way, producing a .tar.bz2 file. #
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# #
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#######################################################
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$counter = 0;
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$saved_bytes = 0;
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$totals_file = '/tmp/machine_bzip2_total';
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$machine_bzip2_total = 0;
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@raw = (defined @ARGV)?@ARGV:<*>;
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foreach(@raw) {
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next if /^bzip/;
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next unless /\.(tgz|gz|Z)$/;
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push @files, $_;
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}
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$total = scalar(@files);
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foreach (@files) {
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if (/tgz$/) {
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($new=$_) =~ s/tgz$/tar.bz2/;
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} else {
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($new=$_) =~ s/\.g?z$/.bz2/i;
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}
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$orig_size = (stat $_)[7];
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++$counter;
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print "Repacking $_ ($counter/$total)...\n";
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if ((system "gzip -cd $_ |bzip2 >$new") == 0) {
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$new_size = (stat $new)[7];
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$factor = int(100*$new_size/$orig_size+.5);
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$saved_bytes += $orig_size-$new_size;
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print "$new is about $factor% of the size of $_. :",($factor<100)?')':'(',"\n";
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unlink $_;
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} else {
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print "Arrgghh! Something happened to $_: $!\n";
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}
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}
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print "You've "
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, ($saved_bytes>=0)?"saved ":"lost "
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, abs($saved_bytes)
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, " bytes of storage space :"
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, ($saved_bytes>=0)?")":"("
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, "\n"
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;
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unless (-e '/tmp/machine_bzip2_total') {
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system ('echo "0" >/tmp/machine_bzip2_total');
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system ('chmod', '0666', '/tmp/machine_bzip2_total');
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}
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chomp($machine_bzip2_total = `cat $totals_file`);
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open TOTAL, ">$totals_file"
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or die "Can't open system-wide total: $!";
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$machine_bzip2_total += $saved_bytes;
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print TOTAL $machine_bzip2_total;
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close TOTAL;
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print "That's a machine-wide total of ",`cat $totals_file`," bytes saved.\n";
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</PRE>
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<P>
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<HR>
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