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From: krs@uts.amdahl.com (Kris Stephens [Hail Eris!])
Newsgroups: comp.unix.shell
Subject: Re: sed 's/foobar/$string/g'.... can't do this?
Keywords: sed
Message-ID: <7ejp01gY0c.900@amdahl.uts.amdahl.com>
Date: 21 Jan 91 22:09:46 GMT
References: <1991Jan17.003856.469@unicorn.cc.wwu.edu> <135@edi386.UUCP> <1991Jan21.124531.27867@siesoft.co.uk>
Reply-To: krs@amdahl.uts.amdahl.com (Kris Stephens [Hail Eris!])
Distribution: comp
Organization: Amdahl Corporation, Sunnyvale CA
Lines: 51

>>In article <1991Jan17.003856.469@unicorn.cc.wwu.edu> n8743196@unicorn.cc.wwu.edu (Jeff Wandling) writes:
>>-
>>-I tried:
>>-
>>-set string = newfoobar
>>-cat file | sed 's/foobar/$string/g' ....
>>-
>
>>You might try this :
>
>>	string=newfoobar
>>	cat file | sed 's/foobar/'$string'/g' ...
>

I usually do it like:

	string=newfoobar
	sed "s/foobar/$string/g" file

which saves a fork/exec and pipe for cat.  If you really don't want to
specify the file as an arg to sed,

	sed "s/foobar/$string/g" < file

If the matched string (foobar in the example) needs to include a shell-
special character, obviously you'd need to escape it.  For instance,
if foobar is double-quote delimited and so must the replacement text be:

	string='"newfoobar"'
	sed "s/\"foobar\"/$string/g" < file

The quotes around the definition of string keep the double-quotes from
being evaluated, and the double-quotes around the sed command keep them
from be evaluated there, too.  I think these are easier to read than the
composite string

	sed 's/foobar/'$string'/g'

and safer, too, because the value stored in string won't be evaluated
by the shell if it contains metacharacters.  For example, if string was
set to 'newfoobar?*' (without the contained double-quotes) and the files
newfoobar12 and newfoobar13 existed, sed would replace 'foobar' with
'newfoobar12 newfoobar13' if called 's/foobar/'$string'/g' , making its
editing PWD-dependent.

...Kris
-- 
Kristopher Stephens, | (408-746-6047) | krs@uts.amdahl.com | KC6DFS
Amdahl Corporation   |                |                    |
     [The opinions expressed above are mine, solely, and do not    ]
     [necessarily reflect the opinions or policies of Amdahl Corp. ]