m4

last updated: Oct 20, 2023

https://www.gnu.org/software/m4/manual/m4.html
https://ericscrivner.me/2018/07/m4-as-a-basic-templating-system/

The only widely-available tool on unix systems, but it's a pretty insane tool that doesn't fit with modern sensibilities.

I wish the unix ecosystem were upgrading tools like this more rapidly.

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