If you can enter commands into the shell, you can write shell scripts (also known as Bourne shell scripts). A shell script is a series of commands written in a file; the shell reads the commands from the file just as it would if you typed them into a terminal.
Bourne shell scripts generally start with the following line, which indicates that the
/bin/sh program should execute the commands in the script file. (Make sure that no whitespace appears at the beginning of the script file.)
#! part is called a shebang; you’ll see it in other scripts in this book. You can list any ...