Regular expressions

[Tim Chase]

On 2015-11-04 09:57, Peter Otten wrote:
> Well, I didn't know that grep uses regular expressions by default.

It doesn't help that grep(1) comes in multiple flavors:

grep:  should use BRE (Basic REs)
fgrep:  same as "grep -F"; uses fixed strings, no REs
egrep:  same as "grep -E"; uses ERE (Extended REs)
grep -P: a GNUism to use PCREs (Perl Compatible REs)

there's also an "rgrep" which is just "grep -r" which I find kinda
silly/redundant. Though frankly I feel the same way about fgrep/egrep
since they just activate a command-line switch.

You get even crazier when you start adding zgrep/zegrep/zfgrep.

-tkc