First Shell Script

1: #!/bin/sh 2: PS4="\#> " 3: set -x 4: gcc -Wall -o hello2 hello2.c 5: ./hello2 ece449 6: exit

Create the above script file in a text editor with the name first.

The first line is a “magic” code that identifies the file as a shell script and identifies the shell to be used to run the script.

The last line ensures that the script returns a sensible exit code. Exit codes are rarely checked when scripts are run interactively, as we will be doing, but may be checked when invoked by other scripts.

Making A Script Executable

You can invoke a script in two ways

• Use the shell command:

  1> sh first

• Execute the script directly:

  Make the script excutable for all users by running the chmod

  2> chmod +x first

  Then execute the script calling it by name.

  3> ./first

Maintained by John Loomis, last updated 2 February 2010