Autzoo.627
hacknews
utzoo!henry
Fri May 15 17:10:54 1981
fgrep vs grep vs egrep
Following a comment made by Ron, I ran some timings on the three greps
and uncovered some interesting things.  fgrep "is fast and compact";
I have no doubt about the compact part, but on the example I used
(grepping a single word out of several huge files) it is the SLOWEST
of the three, almost a factor of two slower than egrep, which is the
fastest.  The difference between grep and egrep is not so large but
is not zero.  So egrep is actually the best to use for general work.

A few reservations should accompany the above.  First, it is
indeed possible that fgrep is the fastest if one is searching for
many possible words rather than only one.  And egrep might run out
of space on complex patterns that grep could cope with easily.  Note
also that egrep's patterns are significantly different from the
familiar variety used by the editors, sed, and grep.  And finally,
you are unlikely to notice much of a difference between the greps on
files of ordinary size.