Hi. I received a bug report for gawk by private email that a regexp of this form: '[^0-9---]' wasn't accepted. The bugaboo here is the "---"; it's a range expression consisting of minus through minus, and apparently long ago was how one got a minus into a bracket expression.
This can be seen in current grep also: $ ./src/grep --version ./src/grep (GNU grep) 2.21 Copyright (C) 2014 Free Software Foundation, Inc. ... $ ./src/grep '[^0-9---]' /dev/null ./src/grep: Invalid range end The underlying regex and, I believe, dfa routines don't accept this. Fixing either of them is beyond my skill range, so I thought I'd pass this one upstream to you folks. Thanks! Arnold