Dirname

dirname is a shell command for extracting the directory path portion of a path, without the last name. The command is specified in the Single UNIX Specification and is primarily used in shell scripts.

The version in GNU Core Utilities was written by David MacKenzie and Jim Meyering.^[1] The command is available for Windows as part of the GnuWin32 project^[2] and UnxUtils^[3] and is in IBM i.^[4]

Usage

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

Examples

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
.

Performance

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.

See also

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

References

External links

The Wikibook Guide to Unix has a page on the topic of: Commands

• dirname: return the directory portion of a pathname – Shell and Utilities Reference, The Single UNIX Specification, Version 5 from The Open Group
• dirname(1) – Linux User Commands Manual
• dirname(1) – OpenBSD General Commands Manual