$output =~ s/^((#.*)?\n)*\K/.POSIX:\n\n/; Solaris 10 'perl --version' says it's Perl v5.8.4. v5.8.4 is dated 2004 but \K was added in v5.10
I simply removed the \K, since its only purpose is to optimize use of $& (matched text), but we aren't using $& with this regexp, so far as I can discern. (This line was added for bug#55025, so cc-ing that bug.) This line with the \K didn't exist in 1.16 (it was added in October 2023), so there may well be something else lurking that makes "automake --help" fail on Solaris. We'll see. Now to look into the help2man call in the first place. --thanks, karl. P.S. We could probably replace all uses of $& with other variables, and save some small amount of time, as explained in "Performance issues" in perlvar. I'm not going to go down that road.