With tcsh you can execute files containing TC Shell commands, just as bash can execute files containing Bourne Again Shell commands. The concepts of writing and executing scripts in the two shells are similar. However, the methods of declaring and assigning values to variables and the syntax of control structures are different.
You can run bash and tcsh scripts while using any one of the shells as a command interpreter. Various methods exist for selecting the shell that runs a script. Refer to "#! Specifies a Shell" on page 267 for more information.
If the first character of a shell script is a pound sign (#) and the following character is not an exclamation point (!), the TC Shell executes the script under tcsh. If the first character is anything other than #, tcsh calls the sh copy of bash to execute the script.