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 resolution does not involve '.'  ,  '..'
       ,  or  symbolic links. The generated pathname 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  identified  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 .