topic Re: programming and scripting variable substitution question in Operating System - Linux

programming and scripting variable substitution question

rmueller58 — Thu, 25 Mar 2004 11:32:24 GMT

All,

Attempting to setup a installation/configuration script to quicking blow down a complex setup of applications on RH9.

I have the "software download and installation" complete however, I still have several files that require editing, I would prefer to add these edits to my script using inline editing with perl or sed..

for example:

I have a "/etc/foo/foo.conf"

with in the foo.conf

I have several variables that are set usually manually with vi or emacs,
For example I have a variable with a path attached..
var FOOCONF_PATH ../fooconf

I want to change the FOO_PATH in the foo.conf to a full path

var FOOCONF_PATH /etc/foo/fooconf

I've tried the following:

export FOOPATHOLD "var FOOCONF_PATH ../fooconf"
echo "Enter the new path for FOO Configs"
read $FOOPATHNEW
export FOOPATHNEW
///then I attempt to inline edit using variable substitutions.

I am doing as follows:

cp -p foo.conf foo.conf.orig

perl -p -i -e s/$FOOPATHOLD/$FOOPATHNEW/g foo.conf

the substitution flakes out on me..
I've tried:
perl -p -i -e s/"$FOOPATHOLD"/"$FOOPATHNEW"/g foo.conf

Any thoughts appreciated..

Rex M - Omaha NE

Re: programming and scripting variable substitution question

delahaye_1 — Thu, 25 Mar 2004 11:47:43 GMT

s/FOOPATHOLD/$FOOPATHNEW/g

Re: programming and scripting variable substitution question

Alexander Chuzhoy — Thu, 25 Mar 2004 11:51:22 GMT

How about using File::Basename module?
dirname and basename will be usefull here...

Re: programming and scripting variable substitution question

rmueller58 — Thu, 25 Mar 2004 11:55:47 GMT

Alex not familiar with the module, I will look into it

An down and dirty examples you can throw at me?

Re: programming and scripting variable substitution question

Stuart Browne — Thu, 25 Mar 2004 18:58:35 GMT

Simply put, your issue is with slashes.

Here's an example:

FOOPATH="var FOOCONF_PATH ../fooconf"
FOOPATHNEW="var FOOCONF_PATH /etc/foo/fooconf"

perl -pi -e "s/$FOOPATH/$FOOPATHNEW/g" foo.conf

Expand the -e, and you get:

"s/var FOOCONF_PATH ../fooconf/var FOOCONF_PATH /etc/foo/fooconf/g"

Way broken.

Using something like:

perl -pi -e "s#$FOOPATH#$FOOPATHNEW#g" foo.conf

works just fine however.

Re: programming and scripting variable substitution question

rmueller58 — Fri, 26 Mar 2004 08:50:50 GMT

Stu,
using the "#" is new for me..

Need to get my regexp book out, I tried "!" yesterday, I think I got it now.. Thanks!!!

s#$FOOPATHOLD#$FOONEWPATH# worked.

Rex

Re: programming and scripting variable substitution question

Stuart Browne — Fri, 26 Mar 2004 18:14:36 GMT

You can actually use *any* character. Go Regular Expressions. It's in the documentation somewhere (I read it once upon a time), but can't find it at the moment.

It's just usual to use /'s as they are the default.