For example I am hosting multiple web applications, the development might have several pg_connect command to connect database, in the event I am migrating database to other IP address, it might be hard for them to dig the file and replace the IP Address with new IP Addresses.

In Linux/Unix, you can search through the directories, looking for the files and replace it with the new IP address. Here is the sample.

shell> find /path/to/dir/* -type f -exec sed -i .backup20100714 -e "s/host=x.x.x.x/host=y.y.y.y/g" {} \\;

The command above will search for files in the directory.
find -type f mean look for File only.
find -exec is to execute something from returned results.
sed -i means backup the files, in case you would like to restore later.
sed -e “s/host=x.x.x.x/host=y.y.y.y/g” is to replace x.x.x.x to y.y.y.y

You have backup files name filename.php.backup20100714, now what you need to do is move the files in a backup directory.

shell> find /path/to/dir/* -name "*.backup20100714" -exec mv {} /your/backup/dir/ \\;

You might want to explore on find command, it can do a lot of cool stuffs.

Create a sample file file random name ended with *.sample. Example

touch apple.sample.cfg
touch microsoft.sample.cfg
touch php.sample.cfg
touch config.sample.cfg
touch apache.sample.cfg
touch mysql.sample.cfg
touch pgsql.sample.cfg
touch cacti.sample.cfg
touch wordpress.sample.cfg
touch jessicaalba.sample.cfg

Now you have all the sample configuration, you are going to use them. Are you going to copy one by another and change the same with .cfg prefix? We can do it, in a better and faster way.

Make a new directory to store all the sample file

mkdir sample
cp *.sample.cfg sample/

After that, go to sample directory and copy the files to a location

cd sample 
for d  in `ls *.sample.cfg`; do cp $d `echo $d | sed s/sample.cfg/cfg`; done

That one simple line will easily save you 1-2 minutes.