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REALPATH(3)		   Linux Programmer's Manual		   REALPATH(3)

NAME
       realpath	- return the canonicalized absolute pathname

SYNOPSIS
       #include	<limits.h>
       #include	<stdlib.h>

       char *realpath(const char *path,	char *resolved_path);

   Feature Test	Macro Requirements for glibc (see feature_test_macros(7)):

       realpath():
	   _BSD_SOURCE || _XOPEN_SOURCE	>= 500 ||
	   _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION
       realpath() expands all symbolic links and resolves references  to  /./,
       /../  and  extra	 '/' characters	in the null-terminated string named by
       path to produce a canonicalized absolute	pathname.  The resulting path-
       name is stored as a null-terminated string, up to a maximum of PATH_MAX
       bytes, in the buffer pointed to by resolved_path.  The  resulting  path
       will have no symbolic link, /./ or /../ components.

       If  resolved_path  is specified as NULL,	then realpath()	uses malloc(3)
       to allocate a buffer of up to PATH_MAX bytes to hold the	resolved path-
       name,  and returns a pointer to this buffer.  The caller	should deallo-
       cate this buffer	using free(3).

RETURN VALUE
       If there	 is  no	 error,	 realpath()  returns  a	 pointer  to  the  re-
       solved_path.

       Otherwise, it returns NULL, the contents	of the array resolved_path are
       undefined, and errno is set to indicate the error.

ERRORS
       EACCES Read or search permission	was denied for a component of the path
	      prefix.

       EINVAL path is NULL.  (In glibc versions	before 2.3, this error is also
	      returned if resolved_path	is NULL.)

       EIO    An I/O error occurred while reading from the filesystem.

       ELOOP  Too many symbolic	links  were  encountered  in  translating  the
	      pathname.

       ENAMETOOLONG
	      A	 component  of	a pathname exceeded NAME_MAX characters, or an
	      entire pathname exceeded PATH_MAX	characters.

       ENOENT The named	file does not exist.

       ENOTDIR
	      A	component of the path prefix is	not a directory.

CONFORMING TO
       4.4BSD, POSIX.1-2001.

       POSIX.1-2001 says that the behavior if resolved_path is NULL is	imple-
       mentation-defined.   POSIX.1-2008  specifies  the behavior described in
       this page.

NOTES
       In 4.4BSD and Solaris, the limit	on the pathname	length	is  MAXPATHLEN
       (found  in  _sys/param.h_).  SUSv2 prescribes PATH_MAX and NAME_MAX, as
       found in	_limits.h_ or provided by the pathconf(3) function.  A typical
       source fragment would be

	   #ifdef PATH_MAX
	     path_max =	PATH_MAX;
	   #else
	     path_max =	pathconf(path, _PC_PATH_MAX);
	     if	(path_max <= 0)
	       path_max	= 4096;
	   #endif

       (But see	the BUGS section.)

   GNU extensions
       If the call fails with either EACCES or ENOENT and resolved_path	is not
       NULL, then the prefix of	path that is not readable or does not exist is
       returned	in resolved_path.

BUGS
       The POSIX.1-2001	standard version of this function is broken by design,
       since it	is impossible to determine a suitable size for the output buf-
       fer,  resolved_path.   According	 to  POSIX.1-2001  a  buffer  of  size
       PATH_MAX	suffices, but PATH_MAX need not	be a defined constant, and may
       have to be obtained using pathconf(3).  And asking pathconf(3) does not
       really help, since, on the one hand POSIX  warns	 that  the  result  of
       pathconf(3) may be huge and unsuitable for mallocing memory, and	on the
       other hand pathconf(3) may return -1 to signify that  PATH_MAX  is  not
       bounded.	   The	resolved_path == NULL  feature,	 not  standardized  in
       POSIX.1-2001, but standardized  in  POSIX.1-2008,  allows  this	design
       problem to be avoided.

SEE ALSO
       realpath(1),  readlink(2),  canonicalize_file_name(3), getcwd(3), path-
       conf(3),	sysconf(3)

COLOPHON
       This page is part of release 3.74 of the	Linux  man-pages  project.   A
       description  of	the project, information about reporting bugs, and the
       latest	 version    of	  this	  page,	   can	   be	  found	    at
       http://www.kernel.org/doc/man-pages/.

				  2014-10-02			   REALPATH(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | BUGS | SEE ALSO | COLOPHON

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