Mastering Linux Shell Scripting - Second Edition

Checking the exit status

This script is simple, but we still need to know how to make use of the exit codes from scripts and other applications. The command-line list that we generated earlier, while creating the $HOME/bin directory, is a good example of how we can use the exit code:

$ command1 || command 2 

In the preceding example, command2 is executed only if command1 fails in some way. To be specific, command2 will run if command1 exits with a status code other than 0.

Similarly, in the following extract, we will only execute command2 if command1 succeeds and issues an exit code of 0:

$ command1 && command2  

To read the exit code from our script explicitly, we can view the $? variable, as shown in the following example:

$ hello1.sh