From: bob@... (Bob Proulx)
Date: 2007-09-07T12:22:13+09:00
Subject: Re: subject line

M. Edward (Ed) Borasky wrote:
> "grep" standing for "Generalized Regular Expression Processor", etc.

Being the pedant that I am I have to clarify this statement.  The
'grep' name came from use in 'ed' and similar editors.  Of course
ed-like editors were the standard editors at the time that grep was
written.  Why were line editors used?  Because a screen editor just
does not function well on the paper printing terminals commonly in use
at that time. :-)

A common operation by anyone who uses a line editor is to print lines
matching a pattern in the file.  The way to do this in 'ed' is the
following:

  $ ed somefile
  g/RE/p
  q

The 'q' quits the editor (in case you try this and need to know how to
get out of the program).  The /RE/ is a regular expression pattern.
If the RE matches then invoke the command-list.  The 'g' is a suffix
to globally operate on every line in the file.  Without the 'g'
(global) suffix the command would operate only on the current line.
The 'p' is the command-list item to print.

Putting this all together the command reads, globally operate on every
line of the file, if a line matches the regular expression then print
it.  Global Regular Expression Print.  grep.

Bob