Apropos of regex engines: PCRE [1] is an interesting and somewhat widely used [2] C library for Perl-Compatible Regular Expressions. I was once on a product te

Apropos of regex engines: PCRE [1] is an interesting and somewhat widely used [2] C library for Perl-Compatible Regular Expressions. I was once on a product team where we used PCRE, and one of my tasks was building it from its C source on many Unix variants (such as Linux, Solaris, HP-UX, AIX, Tru64 UNIX, etc.) and Windows (x 32/64-bit OS versions for some of them). I learned something about the differences between the C compiler toolchains on all those OSes in the process. There was quite a bit of variation between them, in the commands and steps needed to compile and link programs. [1] https://www.pcre.org/ https://www.pcre.org/ https://en.wikipedia.org/wiki/Perl_Compatible_Regular_Expressions https://en.wikipedia.org/wiki/Perl_Compatible_Regular_Expres... https://en.wikipedia.org/wiki/Philip_Hazel https://en.wikipedia.org/wiki/Philip_Hazel (PCRE creator) [2] From the Wikipedia article about PCRE: >A number of prominent open-source programs, such as the Apache and Nginx HTTP Servers, and the PHP and R scripting languages, incorporate the PCRE library; proprietary software can do likewise, as the library is BSD licensed. As of Perl 5.10, PCRE is also available as a replacement for Perl's default regular expression engine through the re::engine::PCRE module. >The library can be built on Unix, Windows, and several other environments. PCRE is distributed with a POSIX C wrapper, a native C++ wrapper,[a] several test programs, and the utility program pcregrep built in tandem with the library.