From: utzoo!decvax!ittvax!swatt
Newsgroups: net.unix-wizards
Title: Re: grep
Article-I.D.: ittvax.657
Posted: Wed Mar 16 10:07:07 1983
Received: Wed Mar 23 00:26:07 1983
References: floyd.1304

Andy's performed a valuable service showing USENET readers just what a
wonderful job "egrep" is.  I remember being completely blown away back
in 1979 when I discovered comparing the three "grep"s on multi-megabyte
listing files using an 11/70, and discovered "egrep" was the fastest of
the lot, even on very long expressions.  It demonstrates once again the
power of good algorithms.

However I still use good 'ol "grep" most of the time because (1) my
fingers are VERY good at typing it, and (2) it has fewer metacharacters
that I have to escape if I want them literally.

Also note that "egrep" takes a fair amount of time to just compile that
regular expression, whereas "grep" is very fast.  Take a look at
/bin/calendar: it creates a file with two egrep-style regular
expressions, and then "egrep"s through calendar files using that file
as the set of regular expressions.  The time required for egrep to
actually process the input is trivial, but it can take a significant
fraction of a CPU second to compile the expression.

Also, "grep" has some options which "egrep" lacks, notably the "ignore
case" flag.

Conclusion:  The grep man page authors are right -- there isn't yet one
grep for all seasons.

	- Alan S. Watt