centos man page for readlink

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

PROLOG
       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
       readlink - read the contents of a symbolic link

SYNOPSIS
       #include <unistd.h>

       ssize_t readlink(const char *restrict path, char *restrict buf,
	      size_t bufsize);

DESCRIPTION
       The readlink() function shall place the contents of the symbolic link referred to by path in the buffer buf which has size bufsize. If  the
       number of bytes in the symbolic link is less than bufsize, the contents of the remainder of buf are unspecified. If the buf argument is not
       large enough to contain the link content, the first bufsize bytes shall be placed in buf.

       If the value of bufsize is greater than {SSIZE_MAX}, the result is implementation-defined.

RETURN VALUE
       Upon successful completion, readlink() shall return the count of bytes placed in the buffer. Otherwise, it shall  return  a  value  of  -1,
       leave the buffer unchanged, and set errno to indicate the error.

ERRORS
       The readlink() function shall fail if:

       EACCES Search permission is denied for a component of the path prefix of path.

       EINVAL The path argument names a file that is not a symbolic link.

       EIO    An I/O 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 path argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.

       ENOENT A component of path does not name an existing file or path is an empty string.

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

       The readlink() function may fail if:

       EACCES Read permission is denied for the directory.

       ELOOP  More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.

       ENAMETOOLONG
	      As  a  result  of  encountering  a  symbolic  link in resolution of the path argument, the length of the substituted pathname string
	      exceeded {PATH_MAX}.

       The following sections are informative.

EXAMPLES
   Reading the Name of a Symbolic Link
       The following example shows how to read the name of a symbolic link named /modules/pass1.

	      #include <unistd.h>

	      char buf[1024];
	      ssize_t len;
	      ...
	      if ((len = readlink("/modules/pass1", buf, sizeof(buf)-1)) != -1)
		  buf[len] = '';

APPLICATION USAGE
       Conforming applications should not assume that the returned contents of the symbolic link are null-terminated.

RATIONALE
       Since IEEE Std 1003.1-2001 does not require any association of file times with symbolic links, there is no requirement that file  times	be
       updated	by  readlink(). The type associated with bufsiz is a size_t in order to be consistent with both the ISO C standard and the defini-
       tion of read().	The behavior specified for readlink() when bufsiz is zero represents historical practice.  For	this  case,  the  standard
       developers  considered a change whereby readlink() would return the number of non-null bytes contained in the symbolic link with the buffer
       buf remaining unchanged; however, since the stat structure member st_size value can be used to determine the size of  buffer  necessary	to
       contain the contents of the symbolic link as returned by readlink(), this proposal was rejected, and the historical practice retained.

FUTURE DIRECTIONS
       None.

SEE ALSO
       lstat(), stat(), symlink(), the Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- 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							      READLINK(3P)