> A pcregrep utility also used to exist, if you want expansive perl-compatible regular expressions. This has been absorbed into GNU grep with the -P option.
'pcregrep' still exists. But with PCRE2 supplanting PCRE, it is now spelled 'pcre2grep'.
I don't know the precise history of 'grep -P' and whether 'pcregrep' was actually absorbed into it, but 'pcregrep' is its own thing with its own features. For example, it has a -M/--multiline flag that no standard grep (that I'm aware of) has. (Although there are some work-arounds, e.g., by treating NUL as the line terminator via the -z/--null-data flag in GNU grep.)
Oddly, there are pcre2 packages in RedHat/Alma 9, but they do not include a pcre2grep.
GNU grep is also linked to pcre, not pcre2.
# pcre2grep
bash: pcre2grep: command not found...
# yum install pcre2grep
Last metadata expiration check: 1:58:58 ago on Tue 13 Dec 2022 11:45:44 AM CST.
No match for argument: pcre2grep
Error: Unable to find a match: pcre2grep
# yum whatprovides pcre2grep
Last metadata expiration check: 2:09:25 ago on Tue 13 Dec 2022 11:45:44 AM CST.
Error: No matches found.
# rpm -qa | grep pcre2 | sort
pcre2-10.40-2.0.2.el9.x86_64
pcre2-syntax-10.40-2.0.2.el9.noarch
pcre2-utf32-10.40-2.0.2.el9.x86_64
# which grep
/usr/bin/grep
# ldd /usr/bin/grep | grep pcre
libpcre.so.1 => /lib64/libpcre.so.1 (0x00007efc473c4000)
'pcregrep' still exists. But with PCRE2 supplanting PCRE, it is now spelled 'pcre2grep'.
I don't know the precise history of 'grep -P' and whether 'pcregrep' was actually absorbed into it, but 'pcregrep' is its own thing with its own features. For example, it has a -M/--multiline flag that no standard grep (that I'm aware of) has. (Although there are some work-arounds, e.g., by treating NUL as the line terminator via the -z/--null-data flag in GNU grep.)