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Linux 2.6 - man page for realpath (linux section 3posix)

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

       realpath - resolve a pathname

       #include <stdlib.h>

       char *realpath(const char *restrict file_name,
	      char *restrict resolved_name);

       The  realpath() function shall derive, from the pathname pointed to by file_name, an abso-
       lute 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.

       Upon successful completion, realpath() shall return a pointer to the resolved name. Other-
       wise,  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.

       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.

	      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.

	      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.

	      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.

   Generating an Absolute Pathname
       The following example generates an absolute pathname for the file identified by	the  sym-
       linkpath 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);


       Since  the  maximum pathname length is arbitrary unless {PATH_MAX} is defined, an applica-
       tion generally cannot supply a resolved_name buffer with size {{PATH_MAX}+1}.

       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.

       getcwd() , sysconf() , the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>

       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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				      REALPATH(P)

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