10 Aug
2020
10 Aug
'20
5:44 a.m.
On Sat, 1 Aug 2020, Doug McIlroy wrote:
This lesson came home with a vengeance when Al Aho
wrote egrep, which
implemented full regular expressions as DFA's. I happened to be writing
calendar(1) at the same time, and used egrep to search calendar files
for dates in rather free formats for today and all days through the next
working day. [...]
I heard somewhere (a Usenix paper?) that "egrep" turned out to be faster
than "fgrep" (designed to look for fixed strings only), thus "egrep"
is
now symlinked everywhere.
On my FreeBSD box (in /usr/bin):
aneurin% ls -li *grep
25471 -r-xr-xr-x 7 root wheel 40744 Oct 15 2017 bsdgrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 bzegrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 bzfgrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 bzgrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 egrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 fgrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 grep
25471 -r-xr-xr-x 7 root wheel 40744 Oct 15 2017 lzegrep
25471 -r-xr-xr-x 7 root wheel 40744 Oct 15 2017 lzfgrep
25471 -r-xr-xr-x 7 root wheel 40744 Oct 15 2017 lzgrep
23554 lrwxr-xr-x 1 root wheel 10 Feb 18 2011 pgrep -> /bin/pgrep
25471 -r-xr-xr-x 7 root wheel 40744 Oct 15 2017 xzegrep
25471 -r-xr-xr-x 7 root wheel 40744 Oct 15 2017 xzfgrep
25471 -r-xr-xr-x 7 root wheel 40744 Oct 15 2017 xzgrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 zegrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 zfgrep
25480 -r-xr-xr-x 9 root wheel 82136 Oct 15 2017 zgrep
OK, there's a few strays in there...
-- Dave