1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)readlink.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD$ 30.\" 31.Dd March 30, 2020 32.Dt READLINK 2 33.Os 34.Sh NAME 35.Nm readlink , 36.Nm readlinkat 37.Nd read value of a symbolic link 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In unistd.h 42.Ft ssize_t 43.Fn readlink "const char *restrict path" "char *restrict buf" "size_t bufsiz" 44.Ft ssize_t 45.Fo readlinkat 46.Fa "int fd" "const char *restrict path" "char *restrict buf" "size_t bufsize" 47.Fc 48.Sh DESCRIPTION 49The 50.Fn readlink 51system call 52places the contents of the symbolic link 53.Fa path 54in the buffer 55.Fa buf , 56which has size 57.Fa bufsiz . 58The 59.Fn readlink 60system call does not append a 61.Dv NUL 62character to 63.Fa buf . 64.Pp 65The 66.Fn readlinkat 67system call is equivalent to 68.Fn readlink 69except in the case where 70.Fa path 71specifies a relative path. 72In this case the symbolic link whose content is read relative to the 73directory associated with the file descriptor 74.Fa fd 75instead of the current working directory. 76If 77.Fn readlinkat 78is passed the special value 79.Dv AT_FDCWD 80in the 81.Fa fd 82parameter, the current working directory is used and the behavior is 83identical to a call to 84.Fn readlink . 85.Sh RETURN VALUES 86The call returns the count of characters placed in the buffer 87if it succeeds, or a \-1 if an error occurs, placing the error 88code in the global variable 89.Va errno . 90.Sh ERRORS 91The 92.Fn readlink 93system call 94will fail if: 95.Bl -tag -width Er 96.It Bq Er ENOTDIR 97A component of the path prefix is not a directory. 98.It Bq Er ENAMETOOLONG 99A component of a pathname exceeded 255 characters, 100or an entire path name exceeded 1023 characters. 101.It Bq Er ENOENT 102The named file does not exist. 103.It Bq Er EACCES 104Search permission is denied for a component of the path prefix. 105.It Bq Er ELOOP 106Too many symbolic links were encountered in translating the pathname. 107.It Bq Er EINVAL 108The named file is not a symbolic link. 109.It Bq Er EIO 110An I/O error occurred while reading from the file system. 111.It Bq Er EINTEGRITY 112Corrupted data was detected while reading from the file system. 113.It Bq Er EFAULT 114The 115.Fa buf 116argument 117extends outside the process's allocated address space. 118.El 119.Pp 120In addition to the errors returned by the 121.Fn readlink , 122the 123.Fn readlinkat 124may fail if: 125.Bl -tag -width Er 126.It Bq Er EBADF 127The 128.Fa path 129argument does not specify an absolute path and the 130.Fa fd 131argument is neither 132.Dv AT_FDCWD 133nor a valid file descriptor open for searching. 134.It Bq Er ENOTDIR 135The 136.Fa path 137argument is not an absolute path and 138.Fa fd 139is neither 140.Dv AT_FDCWD 141nor a file descriptor associated with a directory. 142.El 143.Sh SEE ALSO 144.Xr lstat 2 , 145.Xr stat 2 , 146.Xr symlink 2 , 147.Xr symlink 7 148.Sh STANDARDS 149The 150.Fn readlinkat 151system call follows The Open Group Extended API Set 2 specification. 152.Sh HISTORY 153The 154.Fn readlink 155system call appeared in 156.Bx 4.2 . 157The 158.Fn readlinkat 159system call appeared in 160.Fx 8.0 . 161