Dirname

dirname
Example of dirname command
Developer(s)	Various open-source and commercial developers
Operating system	Unix, Unix-like, IBM i
Platform	Cross-platform
Type	Command
License	coreutils: GPLv3+

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 via UnxUtils,^[2] and is in IBM i.^[3]

The Single UNIX Specification is: dirname path.

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

$ dirname /home/martin/docs/base.wiki
/home/martin/docs

$ dirname /home/martin/docs/
/home/martin

$ dirname base.wiki
.

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

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