How to check write permissions?

To check write permissions for a file in a shell script, you can use the -w option in a conditional expression. Here's an example:

filename="test_file.txt"
if [ -w "$filename" ]; then
    echo "You have write permissions for $filename."
else
    echo "You do not have write permissions for $filename."
fi

In this code:

• The -w option checks if the file specified by filename is writable.
• If the file is writable, the message indicating write permissions will be printed; otherwise, a message indicating lack of write permissions will be shown.