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>