sed 's/foobar/$string/g'.... can't do this?

[Kris Stephens [Hail Eris!]]

>>In article <1991Jan17.003856.469 at unicorn.cc.wwu.edu> n8743196 at 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 at uts.amdahl.com | KC6DFS
Amdahl Corporation   |                |                    |
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