NAME

basename — return the last component of a pathname

SYNOPSIS

[XSI]
#include <libgen.h>

char *basename(char *path);

DESCRIPTION

The basename () function shall take the pathname pointed to by path and return a pointer to the final component of the pathname, deleting any trailing ‘/’ characters.

If the string pointed to by path consists entirely of the ‘/’ character, basename () shall return a pointer to the string "/". If the string pointed to by path is exactly "//", it is implementation-defined whether ‘/’ or "//" is returned.

If path is a null pointer or points to an empty string, basename () shall return a pointer to the string ".".

The basename () function may modify the string pointed to by path, and may return a pointer to internal storage. The returned pointer might be invalidated or the storage might be overwritten by a subsequent call to basename (). The returned pointer might also be invalidated if the calling thread is terminated.

The basename () function need not be thread-safe.

RETURN VALUE

The basename () function shall return a pointer to the final component of path.

ERRORS

No errors are defined.

The following sections are informative.

EXAMPLES

Using basename()

The following program fragment returns a pointer to the value lib, which is the base name of /usr/lib.

#include <libgen.h>
...
char name[] = "/usr/lib";
char *base;


base = basename(name);
...

Sample Input and Output Strings for the basename() and dirname() Functions and the basename and dirname Utilities

basename() and dirname Functions path Argument	String returned by basename()	String returned by dirname()	basename and dirname Utilities string Operand	Output Written by basename utility	Output Written by dirname utility
usr	usr	.	usr	usr	.
usr/	usr	.	usr/	usr	.
	.	.		. or empty string	.
/	/	/	/	/	/
//	/ or //	/ or //	//	/ or //	/ or //
///	/	/	///	/	/
/usr/	usr	/	/usr/	usr	/
/usr/lib	lib	/usr	/usr/lib	lib	/usr
//usr//lib//	lib	//usr	//usr//lib//	lib	//usr
/home//dwc//test	test	/home//dwc	/home//dwc//test	test	/home//dwc

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

CHANGE HISTORY

First released in Issue 4, Version 2.

Issue 5

Moved from X/OPEN UNIX extension to BASE.

Normative text previously in the APPLICATION USAGE section is moved to the DESCRIPTION.

A note indicating that this function need not be reentrant is added to the DESCRIPTION.

Issue 6

In the DESCRIPTION, the note about reentrancy is expanded to cover thread-safety.

IEEE Std 1003.1-2001 (“POSIX.1”)/Cor 2-2004, item XSH/TC2/D6/20 is applied, changing the DESCRIPTION to make it clear that the string referenced is the string pointed to by path .

Issue 7

Austin Group Interpretation 1003.1-2001 #156 is applied.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0041 [75] is applied.

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0047 [656], XSH/TC2-2008/0048 [928], and XSH/TC2-2008/0049 [612] are applied.

End of informative text.