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basename(3) — Linux manual page

basename(3)              Library Functions Manualbasename(3)

NAME        top

       basename, dirname - parse pathname components

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

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

DESCRIPTION        top

       Warning: there are two different functionsbasename(); see below.       The functionsdirname() andbasename() break a null-terminated       pathname string into directory and filename components.  In the       usual case,dirname() returns the string up to, but not including,       the final '/', andbasename() returns the component following the       final '/'.  Trailing '/' characters are not counted as part of the       pathname.       Ifpath does not contain a slash,dirname() returns the string "."       whilebasename() returns a copy ofpath.  Ifpath is the string       "/", then bothdirname() andbasename() return the string "/".  Ifpath is a null pointer or points to an empty string, then bothdirname() andbasename() return the string ".".       Concatenating the string returned bydirname(), a "/", and the       string returned bybasename() yields a complete pathname.       Bothdirname() andbasename() may modify the contents ofpath, so       it may be desirable to pass a copy when calling one of these       functions.       These functions may return pointers to statically allocated memory       which may be overwritten by subsequent calls.  Alternatively, they       may return a pointer to some part ofpath, so that the string       referred to bypath should not be modified or freed until the       pointer returned by the function is no longer required.       The following list of examples (taken from SUSv2) shows the       strings returned bydirname() andbasename() for different paths:path       dirname   basename              /usr/lib   /usr      lib              /usr/      /         usr              usr        .         usr              /          /         /              .          .         .              ..         .         ..

RETURN VALUE        top

       Bothdirname() andbasename() return pointers to null-terminated       strings.  (Do not pass these pointers tofree(3).)

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────────────────────┬───────────────┬─────────┐       │Interface│Attribute│Value│       ├──────────────────────────────────────┼───────────────┼─────────┤       │basename(),dirname()                │ Thread safety │ MT-Safe │       └──────────────────────────────────────┴───────────────┴─────────┘

VERSIONS        top

       There are two different versions ofbasename() - the POSIX version       described above, and the GNU version, which one gets after#define _GNU_SOURCE/* See feature_test_macros(7) */#include <string.h>       The GNU version never modifies its argument, and returns the empty       string whenpath has a trailing slash, and in particular also when       it is "/".  There is no GNU version ofdirname().       With glibc, one gets the POSIX version ofbasename() when<libgen.h> is included, and the GNU version otherwise.

STANDARDS        top

       POSIX.1-2008.

HISTORY        top

       POSIX.1-2001.

BUGS        top

       In the glibc implementation, the POSIX versions of these functions       modify thepath argument, and segfault when called with a static       string such as "/usr/".       Before glibc 2.2.1, the glibc version ofdirname() did not       correctly handle pathnames with trailing '/' characters, and       generated a segfault if given a NULL argument.

EXAMPLES        top

       The following code snippet demonstrates the use ofbasename() anddirname():           char *dirc, *basec, *bname, *dname;           char *path = "/etc/passwd";           dirc = strdup(path);           basec = strdup(path);           dname = dirname(dirc);           bname = basename(basec);           printf("dirname=%s, basename=%s\n", dname, bname);

SEE ALSO        top

basename(1),dirname(1)

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17basename(3)

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