The join utility is actually a part of POSIX[1], so every UNIX should have one. Here's one from OpenBSD[2], for example. The GNU version probably has more flags though.
[1] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/j...
[2] https://man.openbsd.org/join.1
BTW, there's never a bad time to mention http://johnkerl.org/miller/doc/ ...
The join utility is actually a part of POSIX[1], so every UNIX should have one. Here's one from OpenBSD[2], for example. The GNU version probably has more flags though.
[1] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/j...
[2] https://man.openbsd.org/join.1