SQ

sq ? squeeze a sorted word list unsq ? unsqueeze a sorted word list

sq < infile > outfile

unsq < infile > outfile

sq compresses a sorted list of words (a dictionary). For example:

sort /usr/dict/words | sq | compress > words.sq.Z

will compress dict by about a factor of 4.

unsq uncompress the output of sq. For example:

compress -d < words.sq.Z | unsq | sort -f -o words

will uncompress a dictionary compressed with sq.

The squeezing is achieved by eliminating common prefixes, and replacing them with a single character which encodes the number of characters shared with the preceding word. The prefix size is encoded as a single printable character: 0-9 represent 0-9, A-Z represent 10-35, and a-z represent 36-61.

Mike Wexler

compress(1), sort(1).