AT&T test data from: http://www2.research.att.com/~gsf/testregex/ The above link does not exist anymore; a copy of it is maintained at: https://github.com/gburd/testregex Quoting from the page: testregex.c 2004-05-31 is the latest source for the AT&T Research regression test harness for the X/Open regex pattern match interface. See testregex(1) for option and test input details. The source and test data posted here are license free.