[ILUG] grep, egrep, fgrep

[Scanlan, Brian (5188)]

Hey,

This is on RH 6.1 and 6.2...

# ls -ali /bin/grep /bin/egrep /bin/fgrep
  16537 -rwxr-xr-x   1 root     root        47452 Mar 21  1999 /bin/egrep
  16538 -rwxr-xr-x   1 root     root        47452 Mar 21  1999 /bin/fgrep
  16539 -rwxr-xr-x   1 root     root        47452 Mar 21  1999 /bin/grep

Oooh, same sized file. Diff reckons they're different though.

# diff /bin/egrep /bin/grep
Binary files /bin/egrep and /bin/grep differ

Hmm. Let's get a strings output...

# strings /bin/egrep >/tmp/egrep.strings
# strings /bin/fgrep >/tmp/fgrep.strings
# diff /tmp/egrep.strings /tmp/fgrep.strings
272c272
< egrep
---
> fgrep

Is it just me, or are these three binarys the exact same apart 
from a string containing their name, it'd be silly if they don't 
act as their argv[0] says they should. 

Though this guy disagrees. 
http://mail.gnu.org/pipermail/bug-gnu-utils/2000-January/000616.html

Brian.

-----Original Message-----
From: Niall O Broin [mailto:niall at magicgoeshere.com]
Sent: 02 February 2001 14:04
To: ilug at linux.ie
Subject: [ILUG] grep, egrep, fgrep


Can anyone shed any light on why the above, at least on SuSE 6.4, are
entirely separate programs ? As egrep is e.g functionally identical to grep
-E and the man page for grep says

In addition, two variant programs egrep and fgrep are available.  Egrep is
the same as grep -E.  Fgrep is the same as grep -F.

why are grep, egrep, and fgrep not just links to the same file, and the
program decides what to do according to its name as is quie common behaviour
with Gnu tools ?


This anomalous behaviour has just cost me a couple of blank CDs and more
important, a couple of hours, so I'm pissed ! (Yes, I know it's my fault for
making unjustified assumptions, but I'm still pissed !)