How to Determine the Script File Name in a Bash Script

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Knowing the script file name within a Bash script is often necessary for logging, debugging, and dynamic script behavior. This guide will explain how to retrieve the script file name, providing clear and practical instructions.

Why Knowing the Script File Name is Useful

  1. Logging: Including the script name in log messages helps in identifying which script generated the logs.
  2. Debugging: Knowing the script name helps in debugging issues when multiple scripts are involved.
  3. Dynamic Behavior: Scripts can change behavior based on their name, making them more versatile.

Retrieving the Script File Name Using $0

In Bash, the special variable $0 holds the name of the script being executed. This variable includes the path used to call the script.

Example Script

#!/bin/bash

script_name="$0"
echo "The script file name is: $script_name"

Explanation:

  • #!/bin/bash: Specifies that the script should be run using the Bash shell.
  • script_name="$0": Assigns the name of the script to the variable script_name.
  • echo "The script file name is: $script_name": Prints the script file name.

When you run this script, the output will be something like:

The script file name is: ./your_script.sh

Removing the Path from the Script Name

If you only want the script name without the path, use the basename command.

Example Script with basename

#!/bin/bash

script_name=$(basename "$0")
echo "The script file name is: $script_name"

Explanation:

  • basename "$0": Extracts the file name from the full path, removing any directory components.

When you run this script, the output will be:

The script file name is: your_script.sh

Handling Different Execution Contexts

When a script is sourced (source script.sh or . script.sh), $0 will contain the name of the current shell (e.g., bash or sh) instead of the script name. To handle this, you can use a function to determine if the script is being sourced.

Example Script to Handle Sourcing

#!/bin/bash

get_script_name() {
  if [ "${BASH_SOURCE[0]}" != "${0}" ]; then
    echo "This script is being sourced."
  else
    echo "The script file name is: $(basename "${BASH_SOURCE[0]}")"
  fi
}

get_script_name

Explanation:

  • BASH_SOURCE[0]: Provides the name of the script even when sourced.
  • The condition [ "${BASH_SOURCE[0]}" != "${0}" ] checks if the script is being sourced.

When run normally:

./your_script.sh

Output:

The script file name is: your_script.sh

When sourced:

source your_script.sh

Output:

This script is being sourced.

Conclusion

Determining the script file name in a Bash script using $0 or basename "$0" provides essential information for logging, debugging, and dynamic behavior. By incorporating these methods, you can enhance the functionality and usability of your Bash scripts, ensuring they operate effectively in different environments and scenarios. This approach not only makes your scripts more robust but also aids in maintaining clear and informative logs, crucial for efficient troubleshooting and monitoring.