Command line:
Open terminal and type following command "#mv filename.oldextension filename.newextension"
For example if you want to change "index.html" to "index.php" you would type the following command.
#mv index.html index.php
Graphical Mode:
Same as Microsoft Windows right click and rename its extension.
Multiple file extension change.
for x in *.html; do mv "$x" "${x%.html}.php"; done
This script will change all files in current directory ending with html extension to
php extension. (*.html to *.php), You can customize it as per your requirment.
