What is the purpose of using the -r test in the script?

The -r test in a script is used to check if a specified file or directory is readable. It returns true if the file exists and the user has read permissions for it. This is particularly useful for ensuring that a script can access the necessary files before attempting to read from them, which helps prevent errors and improves the robustness of the script.

For example, in a bash script, you might see something like this:

if [ -r filename.txt ]; then
    echo "File is readable."
else
    echo "File is not readable."
fi

In this snippet, the script checks if filename.txt is readable and provides feedback accordingly.