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.\"     @(#)readlink.2	8.1 (Berkeley) 6/4/93
.\"
.Dd $Mdocdate: May 31 2015 $
.Dt READLINK 2
.Os
.Sh NAME
.Nm readlink ,
.Nm readlinkat
.Nd read value of a symbolic link
.Sh SYNOPSIS
.In unistd.h
.Ft ssize_t
.Fn readlink "const char *restrict path" "char *restrict buf" "size_t bufsiz"
.In fcntl.h
.In unistd.h
.Ft ssize_t
.Fn readlinkat "int fd" "const char *path" "char *buf" "size_t bufsiz"
.Sh DESCRIPTION
The
.Fn readlink
function places the contents of the symbolic link
.Fa path
in the buffer
.Fa buf ,
which has size
.Fa bufsiz .
.Fn readlink
does not append a
.Dv NUL
character to
.Fa buf .
.Pp
The
.Fn readlinkat
function is equivalent to
.Fn readlink
except that where
.Fa path
specifies a relative path,
the symbolic link whose contents are read is determined relative to
the directory associated with file descriptor
.Fa fd
instead of the current working directory.
.Pp
If
.Fn readlinkat
is passed the special value
.Dv AT_FDCWD
(defined in
.In fcntl.h )
in the
.Fa fd
parameter, the current working directory is used
and the behavior is identical to a call to
.Fn readlink .
.Sh 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
.Va errno .
.Sh ERRORS
.Fn readlink
and
.Fn readlinkat
will fail if:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Dv NAME_MAX
characters, or an entire pathname (including the terminating NUL)
exceeded
.Dv PATH_MAX
bytes.
.It Bq Er ENOENT
The named file does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EINVAL
The named file is not a symbolic link.
.It Bq Er EIO
An I/O error occurred while reading from the file system.
.It Bq Er EFAULT
.Fa buf
or
.Fa path
extends outside the process's allocated address space.
.El
.Pp
Additionally,
.Fn readlinkat
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa path
argument specifies a relative path and the
.Fa fd
argument is neither
.Dv AT_FDCWD
nor a valid file descriptor.
.It Bq Er ENOTDIR
The
.Fa path
argument specifies a relative path and the
.Fa fd
argument is a valid file descriptor but it does not reference a directory.
.It Bq Er EACCES
The
.Fa path
argument specifies a relative path but search permission is denied
for the directory which the
.Fa fd
file descriptor references.
.El
.Sh SEE ALSO
.Xr lstat 2 ,
.Xr stat 2 ,
.Xr symlink 2 ,
.Xr symlink 7
.Sh STANDARDS
The
.Fn readlink
and
.Fn readlinkat
functions conform to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn readlink
system call first appeared in
.Bx 4.1c .
The
.Fn readlinkat
system call has been available since
.Ox 5.0 .