bzip2-0.9.5d: description + notes
Bzip2 compresses files using the Burrows-Wheeler block-sorting text compression algorithm, and Huffman coding.

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, bzip2 is slower and gives a slightly better compression. Decompression is significantly slower than gzip. 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. The input data was a 27172606 byte file, comprised of roughly 17.5MB of text and 9.5MB of binary data (a copy of /unix).

command user time size        command user time size
gzip -1 21.574s 10058082 bzip2 -1 136.902s 7755985
gzip -2 24.466s 9704716 bzip2 -2 146.684s 7440374
gzip -3 32.709s 9390728 bzip2 -3 153.654s 7284446
gzip -4 32.301s 8974083 bzip2 -4 162.805s 7204124
gzip -5 48.635s 8697843 bzip2 -5 167.191s 7141193
gzip -6[*] 75.872s 8569328 bzip2 -6 171.074s 7096121
gzip -7 96.364s 8542842 bzip2 -7 176.393s 7066566
gzip -8 145.333s 8516674 bzip2 -8 182.043s 7055641
gzip -9 227.150s 8508851 bzip2 -9[*] 187.077s 7006358
[*] -- default setting.
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