Isn't that the very point of picking m4, as it's always there on a POSIX system, whereas a proper scripting language might not be? It's been a while since I saw

Isn't that the very point of picking m4, as it's always there on a POSIX system, whereas a proper scripting language might not be? It's been a while since I saw someone pick m4 when alternatives were present. These days it might be a bit different, as you might either be operating on a very stripped OS (container), and thus might need to provide all your tools anyways, or you might have a standard image with a more wider range of scripting opportunities (even Perl might be a good candidate here, as it's available on any system where you've got a non-restricted git installed).