File rename script
I found plenty of shell scripts that rename the extension of a file however I need a script that, if a the file with a certain extension exists, changes the filename to a preset name and leaves the extension alone. For example if I had the file 123568.txt put into a directory, the script world then change it to file.txt. THe script would change the name to file no matter what the original file was. I want it to run every day and check to see if a file with a certain extension exists and renames it. I'm completely new to shell scripts and would appreciate any help.