readlink(2) [osf1 man page]

readlink(2)							System Calls Manual						       readlink(2)

NAME

       readlink - Reads the value of a symbolic link

SYNOPSIS

       #include <unistd.h>

       int readlink (
	       const char *path,
	       char *buffer,
	       size_t buf_size);

       The following version of the buf_size argument does not conform to current standards and is supported only for backward compatibility:

	       int buf_size

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       readlink():  XSH5.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Specifies  the  pathname  of the destination file or directory.	Points to the user's buffer. The buffer should be at least as large as the
       buf_size parameter.  Specifies the size of the buffer.

DESCRIPTION

       The readlink() function places the contents of the symbolic link named by the path parameter in buffer, which has size buf_size.

       If the actual length of the symbolic link is greater than buf_size, an error is returned.  The length of a symbolic link  will  not  exceed
       PATH_MAX.

       [Tru64 UNIX]  If the actual length of the symbolic link is less than buf_size, the string copied into the buffer is null-terminated.

       For a readlink() function to complete successfully, the calling process must have search access to the directory containing the link.

RETURN VALUES

       Upon successful completion, the readlink() function returns a count of bytes placed in the buffer (not including any terminating null).	If
       the readlink() function fails, the buffer is not modified, a value of -1 is returned, and errno is set to indicate the error.

ERRORS

       The readlink() function sets errno to the specified values for the following conditions:

       Search permission is denied on a component of the path prefix of the path parameter, or read permission is denied on the final component of
       the  path  prefix of the path parameter.  The file named by the path parameter is not a symbolic link.  An I/O error occurred while reading
       from or writing to the file system.  Too many symbolic links were encountered in resolving path.  The length of the path parameter  exceeds
       PATH_MAX,  or a pathname component is longer than NAME_MAX while {_POSIX_NO_TRUNC} is in effect.  The file named by the path parameter does
       not exist or the path parameter points to an empty string.  A component of the path prefix of  the  path  parameter  is	not  a	directory.
       [Tru64 UNIX]  The pathname in the symbolic link is longer than buf_size.

       For  NFS  file  access,	if the readlink() function fails, errno may also be set to one of the following values: [Tru64 UNIX]  The owner or
       group ID is not a value supported by this implementation.  [Tru64 UNIX]	Indicates a stale NFS file handle.  An opened file was deleted	by
       the  server  or	another  client;  a  client cannot open a file because the server has unmounted or unexported the remote directory; or the
       directory that contains an opened file was either unmounted or unexported by the server.

RELATED INFORMATION

       Functions: link(2), stat(2), symlink(2), unlink(2)

       Standards: standards(5) delim off

																       readlink(2)

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READLINK(2)						      BSD System Calls Manual						       READLINK(2)

NAME

     readlink, readlinkat -- read value of a symbolic link

SYNOPSIS

     #include <unistd.h>

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

     ssize_t
     readlinkat(int fd, const char *restrict path, char *restrict buf, size_t bufsize);

DESCRIPTION

     readlink() places the contents of the symbolic link path in the buffer buf, which has size bufsize.  Readlink does not append a NUL character
     to buf.

     The readlinkat() system call is equivalent to readlink() except in the case where path specifies a relative path.	In this case the symbolic
     link whose content is read relative to the directory associated with the file descriptor fd instead of the current working directory.  If
     readlinkat() is passed the special value AT_FDCWD in the fd parameter, the current working directory is used and the behavior is identical to
     a call to readlink().

RETURN VALUES

     The call returns the count of characters placed in the buffer if it succeeds, or a -1 if an error occurs, placing the error code in the
     global variable errno.

ERRORS

     readlink() will fail if:

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

     [EFAULT]		Buf extends outside the process's allocated address space.

     [EINVAL]		The named file is not a symbolic link.

     [EIO]		An I/O error occurred while reading from the file system.

     [ELOOP]		Too many symbolic links are encountered in translating the pathname.  This is taken to be indicative of a looping symbolic
			link.

     [ENAMETOOLONG]	A component of a pathname exceeded {NAME_MAX} characters, or an entire path name (possibly expanded by a symbolic link)
			exceeded {PATH_MAX} characters.

     [ENOENT]		The named file does not exist.

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

     In addition to the errors returned by the readlink(), the readlinkat() may fail if:

     [EBADF]		The path argument does not specify an absolute path and the fd argument is neither AT_FDCWD nor a valid file descriptor
			open for searching.

     [ENOTDIR]		The path argument is not an absolute path and fd is neither AT_FDCWD nor a file descriptor associated with a directory.

LEGACY SYNOPSIS

     #include <unistd.h>

     int
     readlink(const char *path, char *buf, int bufsize);

     The function type and the type of bufsize have changed.

SEE ALSO

     lstat(2), stat(2), symlink(2), compat(5), symlink(7)

STANDARDS

     The readlinkat() system call is expected to conform to POSIX.1-2008 .

HISTORY

     The readlink() function call appeared in 4.2BSD.  The readlinkat() system call appeared in OS X 10.10

4.2 Berkeley Distribution					   June 4, 1993 					 4.2 Berkeley Distribution

Linux and UNIX Man Pages

readlink(2) [osf1 man page]

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