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RedHat 9 (Linux i386) - man page for realpath (redhat section 3)

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);

DESCRIPTION
       realpath expands all symbolic links and resolves references to '/./', '/../' and extra '/'
       characters in the null terminated string named by path and stores the canonicalized  abso-
       lute  pathname  in the buffer of size PATH_MAX named by resolved_path.  The resulting path
       will have no symbolic link, '/./' or '/../' components.

RETURN VALUE
       If there is no error, it returns a pointer to the resolved_path.

       Otherwise it returns a NULL pointer, and the contents of the array resolved_path are unde-
       fined. The global variable errno is set to indicate the error.

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

       EINVAL Either path or resolved_path is NULL. (In libc5 this would just cause a segfault.)

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

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

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

       ENOENT The named file does not exist.

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

BUGS
       The libc4 and libc5 implementation contains a  buffer  overflow	(fixed	in  libc-5.4.13).
       Thus, suid programs like mount need a private version.

       The length of the output buffer should have been an additional parameter, especially since
       pathconf(3) warns that the result of pathconf() may be huge and unsuitable  for	mallocing
       memory.

HISTORY
       The  realpath  function	first  appeared  in BSD 4.4, contributed by Jan-Simon Pendry.  In
       Linux this function appears in libc 4.5.21.

CONFORMING TO
       In BSD 4.4 and  Solaris	the  limit  on	the  pathname  length  is  MAXPATHLEN  (found  in
       <sys/param.h>). The SUSv2 prescribes PATH_MAX and NAME_MAX, as found in <limits.h> or pro-
       vided by the pathconf() 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

       The BSD 4.4, Linux and SUSv2 versions always return an absolute	path  name.  Solaris  may
       return a relative path name when the path argument is relative.	The prototype of realpath
       is given in <unistd.h> in libc4 and libc5, but in <stdlib.h> everywhere else.

SEE ALSO
       readlink(2), getcwd(3), pathconf(3), sysconf(3)

					    1999-08-24				      REALPATH(3)


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