Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!apple!veritas!amdcad!dgcad!dg-rtp!hunt
From: hunt@dg-rtp.rtp.dg.com (Greg Hunt)
Newsgroups: comp.unix.questions
Subject: Re: changing a file
Message-ID: <1991May21.211717.17685@dg-rtp.dg.com>
Date: 21 May 91 21:17:17 GMT
References: <91141.140213KJB6@psuvm.psu.edu>
Sender: hunt@hobbit.rtp.dg.com (Greg Hunt)
Reply-To: hunt@dg-rtp.rtp.dg.com
Organization: Data General Corp., Research Triangle Park, NC
Lines: 42

In article <91141.140213KJB6@psuvm.psu.edu>, KJB6@psuvm.psu.edu writes:
> 
> As a script, I would like to search a file and replace a string with
> another string. I know this can be done, but I have not figure out how to
> do it yet. Anyone have any suggestions. I think if I use awk or nawk
> somewhere
> along the line, I can get it done.
> 
> Any suggestions would be appreciated.

Ken, yes awk or nawk (new awk, which is better), can do the job.  If
it is a simple substitution, using sed might be easier, however.  Try
something like this:

    sed -e 's/old_string/new_string/g' old_file > new_file

This will change every occurrence of "old_string" to "new_string" in
the file.  The 's' is the substitute command, and the 'g' suffix says
to change all occurrences.  Note that you can't actually change the
existing file, you get a new file.  To get the new_file renamed so
that you'll be left with only a file that contains the modifications,
but has the original file name, do this after the sed:

    mv new_file old_file

Take a look at the man page for sed for more examples.  The commands
look much like regular expressions you might use in searches in vi.

Also take a look at the man page for awk for much more sophisticated
processing that you can do using a C like programming language.

Try:

    man sed | more
    man awk | more

Enjoy!

-- 
Greg Hunt                        Internet: hunt@dg-rtp.rtp.dg.com
DG/UX Kernel Development         UUCP:     {world}!mcnc!rti!dg-rtp!hunt
Data General Corporation
Research Triangle Park, NC, USA  These opinions are mine, not DG's.