Calculates the parent directory of a given file or directory path.

# To calculate the parent directory of a given path:
dirname <path/to/file_or_directory>

# To calculate the parent directory of multiple paths:
dirname <path/to/file_a> <path/to/directory_b>

# To delimit output with a NUL character instead of a newline (useful when combining with 'xargs'):
dirname --zero <path/to/directory_a> <path/to/file_b>