Bzip2 compresses files using the Burrows-Wheeler block-sorting text compression algorithm, and Huffman coding.
bzip2-0.1pl2: description + notes
Compression is generally better than that achieved by more conventional LZ77/LZ78-based compressors, and approaches the performance of the PPM family of statistical compressors.
The command-line options are deliberately very similar to those of GNU gzip, but they are not identical.
Compared to
gzip -9, bzip is slower and gives a slightly better compression. Decompression is significantly slower thangzip. Depending on your case, it may be worth it (or not) to invest the extra time in compressing/decompressing with bzip2 instead of the more standard gzip to gain a small advantage in multiple download times, etc.For the curious, here are some running times and compressed file sizes numbers for comparison:
input == 18MB of email plus 4MB Indy kernel plus 4.5MB O2 kernel User time Size --------- ---- gzip -1 50.901 7068389 gzip -2 53.970 6932163 gzip -3 64.538 6817098 gzip -4 73.040 6463509 gzip -5 89.719 6329553 gzip -6 [*] 142.792 6255118 gzip -7 169.861 6209560 gzip -8 251.754 6160528 gzip -9 393.298 6153611 bzip2 -1 588.648 5818442 bzip2 -2 629.891 5664931 bzip2 -3 649.254 5586895 bzip2 -4 676.394 5553740 bzip2 -5 687.309 5532413 bzip2 -6 702.158 5548954 bzip2 -7 714.936 5551827 bzip2 -8 724.542 5512636 bzip2 -9 [*] 732.516 5530767 [*] default
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