sed
Sed on Linux is not the same as sed on macOS!
One word of warning right away before you fall into the same pitfall as I did
(several times!). The sed that is shipped with macOS does not work the same
as GNU sed shipped with a Linux distribution. There are subtle differences
like handling regular expressions or i.e. the -i option.
If you want to be sure to have the same GNU sed as on Linux, install
gnu-sed using Homebrew and then use gsed instead of sed or make your
scripts platform-aware and build the commmands accordingly.