Dirname

dirname
dirname
Developers	Various open-source and commercial developers
Written in	C
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 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.

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.

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

v t e Unix command-line interface programs and shell builtins
File system	cat chattr chmod chown chgrp cksum cmp cp dd du df file fuser ln ls mkdir mv pax pwd rm rmdir split tee touch type umask
Processes	at bg crontab fg kill nice ps time
User environment	env exit logname mesg talk tput uname who write
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Shell builtins	alias cd echo test unset wait
Searching	find grep
Documentation	man
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Miscellaneous	bc cal expr lp od sleep true and false
Categories Standard Unix programs Unix SUS2008 utilities List

v t e GNU Core Utilities command-line interface programs
File system	chcon chmod chown chgrp cksum cp dd df dir dircolors install ln ls mkdir mkfifo mknod mktemp mv realpath rm rmdir shred sync touch truncate vdir
Text utilities	b2sum base32 base64 cat cksum comm csplit cut expand fmt fold head join md5sum nl numfmt od paste ptx pr sha1sum shuf sort split sum tac tail tr tsort unexpand uniq wc
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