BASH - How To (Replace specific text within a file)?

I want to take a template file; which will later be used for an application configuration file and have certain lines within that configuration have a tag that I can later replace with any value when using a script. Example:
(template file)
Max Hold Time: %time%
Path: %path%

-the script runs and would replace those values in that template file with my own values
%time% replaced with 14400
%path% replaced with /somepath/somedirectory

Any ideas?

Thanks...

I know bash itself might not have all the answers, however, any perl or other external applications that you know would do this - an example using that code to do the job would be greatly appreciated. Thanks

#!/bin/bash

time=14400
path=/somepath/somedirectory
sed -e "s!%time%!$time!; s!%path%!$path!" template.txt > file.txt

Bash doesn't have sufficient text manipulation abilities built-in to achieve this; it's a shell after all. You could use bash to execute other programs which could perform these operations, such as sed, or perl.

If you have Perl, I would recommend you use that, and install the Template Toolkit (TT2). http://www.template-toolkit.org/

There are plenty of examples, and TT2 comes with some handy utilities for performing bulk template operations.

I use TT2 for producing HTML, XML, e-mail, CSV, and occasionally TeX. It works well.