DIRNAME(3) Library Functions Manual DIRNAME(3)

dirname — extract the directory part of a pathname

#include <libgen.h>

char *
dirname(char *path);

char *
dirname_r(const char *path, char *dname);

The () function is the converse of basename(3); it returns a pointer to the parent directory of the pathname pointed to by path. Any trailing ‘/’ characters are not counted as part of the directory name. If path is a null pointer, the empty string, or contains no ‘/’ characters, dirname() returns a pointer to the string ".", signifying the current directory.

The dirname() function returns a pointer to internal storage space allocated on the first call that will be overwritten by subsequent calls. dirname_r() is therefore preferred for threaded applications.

Other vendor implementations of dirname() may modify the contents of the string passed to dirname(); if portability is desired, this should be taken into account when writing code which calls this function.

#include <libgen.h>

char *
(const char *path);;

In legacy mode, path will not be changed.

On successful completion, dirname() returns a pointer to the parent directory of path.

If dirname() fails, a null pointer is returned and the global variable errno is set to indicate the error.

The following error codes may be set in errno:

[]
The path component to be returned was larger than MAXPATHLEN.
[]
The static buffer used for storing the path in dirname() could not be allocated.

basename(1), dirname(1), basename(3), compat(5)

The dirname() function conforms to X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”).

The dirname() function first appeared in OpenBSD 2.2 and FreeBSD 4.2. The dirname_r() function first appeared in OS X 10.12.

Todd C. Miller

October 12, 2006 macOS 15.0