SQ

 

NAME

sq, unsq – squeeze or unsqueeze a sorted word list  

SYNOPSIS

sq < infile > outfile

unsq < infile > outfile  

DESCRIPTION

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

sort -u /usr/share/dict/words | sq | gzip -9 > words.sq.gz

will compress dict by about a factor of 5.

unsq uncompress the output of sq. For example:

gunzip < words.sq.gz | 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.  

BUGS

sq and unsq can only handle words of up to 256 characters. The input must be sorted, and duplicates must be suppressed.  

AUTHOR

Mike Wexler