Bash source Command: $0 Can Not Determine Its Own Location

In a Bash script, the $0 variable represents the name of the script itself. However, if the script is being sourced (executed within the current shell environment) rather than run as a separate process, the $0 variable may not behave as expected.

For example, if you use the source command to execute a script within the current shell environment, the $0 variable will not contain the full path to the script, but rather the name of the script as it appears on the command line. For example:

$ source script.sh

In this case, within the script.sh script, the $0 variable will contain the value script.sh, rather than the full path to the script. This can cause issues if the script needs to determine its own location or access other files in the same directory.

To work around this issue, you can use the BASH_SOURCE array, which contains the source filenames for all the scripts that are being sourced. The first element of the BASH_SOURCE array, ${BASH_SOURCE[0]}, will contain the full path to the script, even when the script is being sourced.

For example, to determine the full path to the script when it is being sourced, you can use the following code:

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

This will set the SCRIPT_DIR variable to the full path of the directory containing the script, even when the script is being sourced.

It is important to note that the BASH_SOURCE array is only available in Bash version 4.0 and higher. If you are using an older version of Bash, you