BASENAME(3P) POSIX Programmer's Manual BASENAME(3P)

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

basename — return the last component of a pathname

#include <libgen.h>
char *basename(char *path);

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.

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

No errors are defined.

The following sections are informative.

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);

basename() basename Output Output
and dirname() String String and dirname Written by Written by
Functions path Returned by Returned by Utilities basename dirname
Argument basename() dirname() string Operand Utility 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" "/home//dwc" /home//dwc// test /home//dwc
test" test





The Base Definitions volume of POSIX.1‐2017, <libgen.h>

The Shell and Utilities volume of POSIX.1‐2017, basename

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at .

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2017 IEEE/The Open Group