In the Bash shell, it’s often essential to ascertain the outcome of the last executed command, whether it succeeded or failed. This can be achieved through the utilization of a special parameter: $?
Here’s a straightforward example:
# Execute a command (Example: ls command)
ls non_existent_file.txt
# Retrieve the exit status code
exit_status=$?
# Output the exit status code
echo "Exit status code: $exit_status"
In this example, we tried to list a file (non_existent_file.txt) using ls. After that, we captured the exit status code with $?, stored it in a variable (exit_status), and then displayed it. Understanding and using exit status codes like this can greatly improve your Bash scripting, making error handling clearer and more effective.
Start mastering Bash scripting by learning how to get and use exit status codes for better error handling and smoother automation tasks.
This approach is particularly useful in shell scripts, where you may need to halt execution if a command fails. You can achieve this by checking the exit status code and exiting the script if it indicates failure. Here’s an example:
#!/bin/bash
# Execute a command (e.g., ls)
ls non_existent_file.txt
# Check the exit status code
if [ $? -ne 0 ]; then
echo "Command failed. Exiting script."
exit 1
fi
# Continue with the remaining part of the script
echo "Command succeeded. Continuing with the script."
In this script, if the ls command fails (i.e., exits with a non-zero status code), the script will exit immediately without proceeding further. This ensures that your script behaves as expected, handling errors gracefully and preventing potential issues.