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

PROLOG
       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.
NAME
       realpath - resolve a pathname
SYNOPSIS
       #include <stdlib.h>
       char *realpath(const char *restrict file_name,
              char *restrict resolved_name);

DESCRIPTION
       The realpath() function shall derive, from the pathname pointed  to  by
       file_name, an absolute pathname that names the same file, whose resolu-
       tion does not involve '.', '..', or symbolic links. The generated path-
       name  shall  be  stored as a null-terminated string, up to a maximum of
       {PATH_MAX} bytes, in the buffer pointed to by resolved_name.
       If resolved_name is a null  pointer,  the  behavior  of  realpath()  is
       implementation-defined.
RETURN VALUE
       Upon  successful  completion,  realpath() shall return a pointer to the
       resolved name. Otherwise, realpath() shall return a  null  pointer  and
       set errno to indicate the error, and the contents of the buffer pointed
       to by resolved_name are undefined.
ERRORS
       The realpath() function shall fail if:
       EACCES Read  or  search  permission  was  denied  for  a  component  of
              file_name.
       EINVAL The file_name argument is a null pointer.
       EIO    An error occurred while reading from the file system.
       ELOOP  A loop exists in symbolic links encountered during resolution of
              the path argument.
       ENAMETOOLONG
              The length of the file_name argument  exceeds  {PATH_MAX}  or  a
              pathname component is longer than {NAME_MAX}.
       ENOENT A  component  of  file_name  does  not  name an existing file or
              file_name points to an empty string.
       ENOTDIR
              A component of the path prefix is not a directory.

       The realpath() function may fail if:
       ELOOP  More than {SYMLOOP_MAX} symbolic links were  encountered  during
              resolution of the path argument.
       ENAMETOOLONG
              Pathname  resolution of a symbolic link produced an intermediate
              result whose length exceeds {PATH_MAX}.
       ENOMEM Insufficient storage space is available.

       The following sections are informative.
EXAMPLES
   Generating an Absolute Pathname
       The following example generates an absolute pathname for the file iden-
       tified by the symlinkpath argument. The generated pathname is stored in
       the actualpath array.

              #include <stdlib.h>
              ...
              char *symlinkpath = "/tmp/symlink/file";
              char actualpath [PATH_MAX+1];
              char *ptr;

              ptr = realpath(symlinkpath, actualpath);
APPLICATION USAGE
       None.
RATIONALE
       Since the maximum pathname length is  arbitrary  unless  {PATH_MAX}  is
       defined,  an application generally cannot supply a resolved_name buffer
       with size {{PATH_MAX}+1}.
FUTURE DIRECTIONS
       In  the  future,  passing  a  null  pointer  to  realpath()   for   the
       resolved_name argument may be defined to have realpath() allocate space
       for the generated pathname.
SEE ALSO
       getcwd(),    sysconf(),    the    Base    Definitions     volume     of
       IEEE Std 1003.1-2001, <stdlib.h>
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  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 http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                         REALPATH(3P)