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http://sed.sourceforge.net/sedfaq3.html http://sed.sourceforge.net/sedfaq3.html > Grouping and backreferences: All versions of sed support grouping and backref
by Normal_gaussian 10y ago
http://sed.sourceforge.net/sedfaq3.html http://sed.sourceforge.net/sedfaq3.html
> Grouping and backreferences: All versions of sed support grouping and backreferences on the LHS and backreferences only on the RHS.
- dllthomas 10y agoI saw that. I wasn't sufficiently confident as to whether it meant "all historical versions" or just "all current versions." If the former, then it predated perl by quite a bit, of course.
- Normal_gaussian 10y agoAh I get you. I've tried finding some source for early versions but all the links I've found are dead. It's an interesting question!
- btilly 10y agoPerl started with Henry Spenser's regular expression library, which was written in the mid-1980s. That got used in a lot of places, and may have been used in sed. It includes backreferences. I don't know what predates that. Perl used that as a starting place and began adding extensions such as the difference between .* and .*?. So using "non-regular thing" as a regular expression predates Perl. But the dialect we standardized on with the features people now expect is due to Perl's influence.