John H. Robinson, IV wrote:
Todd Walton wrote:
I want to use sed to take a config file, find an option in the file
and change its value, and to leave the file in place. I want a
portable, scriptable way to do 'vi settings.config', find setting,
edit text, ":wq".
I don't know sed at all, I just know that it does this kind of thing.
What's the best way for a new person to approach getting a basic
understanding of its use?
perl excels at this kind of in-place editing. With sed, you need to
make a copy of the file, use the copy as an input, then write the
changes out to the file itself. With perl, you can specify the file
changes in a sed form, and have perl make the changes in place. You can
also have perl make a backup copy, if that makes you feel safer, all in
one command.
% perl -pi -e 's/(key)=.*/$1=new_value/' file.config
% perl -pi.bak -e 's/(key)=.*/$1=new_value/' file.config
Both of those do the same thing, but the latter will make a copy of the
original file prior to editing. I would recommend reading through the
perlrequick, perlretut, and perlre man pages. They go through regular
expressions quite thoroughly.
-john
As a long time sed and awk user, I find myself using Perl more and more
unless modifying existing scripts. For someone not already familiar
with either sed or awk, your time would be better spent learning Perl.
--
[email protected]
http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
