realpath

 

---

 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 refer­
        ences to '/./', '/../' and extra  '/'  characters  in  the
        null terminated string named by path and stores the canon­
        icalized absolute 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 undefined. The global variable
        errno is set to indicate the error.
 
 ERRORS
        EACCES Read  or  search permission was denied for a compo­
               nent 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  trans­
               lating the pathname.
 
        ENAMETOOLONG
               A  component of a path name exceeded NAME_MAX char­
               acters, 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 over­
        flow  (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  addi­
        tional  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, con­
        tributed 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 provided
        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)

---