Dirname

The Single UNIX Specification is: dirname path. The required argument, path, is a file path string.

The command reports the directory path portion of a path ignoring any trailing slashes.

$ dirname /path/to/filename.ext
/path/to

$ dirname /path/to/
/path

$ dirname filename.ext
.

Since the command accepts only one operand, its usage within the inner loop of a shell script can be detrimental to performance. Consider:

while read file; do
    dirname "$file"
done < some-input

The above causes a separate process invocation for each line of input. For this reason, shell substitution is typically used instead:

echo "${file%/*}";

Or, if relative pathnames need to be handled as well:

if [ -n "${file##*/*}" ]; then
    echo "."
else
    echo "${file%/*}";
fi

Note that these handle trailing slashes differently than dirname.

• basename – Shell command for extracting the last name from a path
• List of POSIX commands