Yep. I was slightly incorrect in my original message, though. SUSv2 (1997) specified egrep and fgrep but marked them LEGACY. POSIX.1-2001 removed them.

The only place that that doesn't support 'grep -E' and 'grep -F' nowadays is Solaris 10. But if you are still using that you will certainly run into many other missing options.

[1] https://pubs.opengroup.org/onlinepubs/007908775/xcu/egrep.ht... [2] https://pubs.opengroup.org/onlinepubs/007908775/xcu/fgrep.ht...