31 Jan
2016
31 Jan
'16
11:38 p.m.
Mary Ann Horton scripsit:
When I tell this story to nontechical folks, I prefix
it with the
brief note that fgrep ought to be fastest, because it's simple, and
egrep ought to be slowest, because it's complex, but in reality
fgrep is slowest and egrep is fastest.
Is it really? The one time I used fgrep in production, I was checking
a a few hundred documents at a time to see which ones contained any of a
few thousand keywords. "fgrep -l -f keywords" seemed to do the job quite
quickly: would it really have been faster to assemble the keywords into
a single egrep regex and use egrep? (This was on Solaris, so using more
or less classic fgrep, not GNU grep.) For a while I referred to myself as
"just another desperate fgrep hacker".
I use "ex" as my normal text editor (including for this email); I drop
into vi mode occasionally, mostly to bounce on the % key when writing
Lisp. Because there is no support for | in ex regexes, I rely on the
low entropy of English text (about 2.7 bits per letter) and search
for e.g. "open|shut" by searching for "[os][ph][eu][nt]". I may
get a few false positives, but they will easily be removed by vgrep.
--
John Cowan http://www.ccil.org/~cowan cowan(a)ccil.org
After fixing the Y2K bug in an application:
WELCOME TO <censored>
DATE: MONDAK, JANUARK 1, 1900