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.Dd March 30, 2020 29.Dt READLINK 2 30.Os 31.Sh NAME 32.Nm readlink , 33.Nm readlinkat 34.Nd read value of a symbolic link 35.Sh LIBRARY 36.Lb libc 37.Sh SYNOPSIS 38.In unistd.h 39.Ft ssize_t 40.Fn readlink "const char *restrict path" "char *restrict buf" "size_t bufsiz" 41.Ft ssize_t 42.Fo readlinkat 43.Fa "int fd" "const char *restrict path" "char *restrict buf" "size_t bufsize" 44.Fc 45.Sh DESCRIPTION 46The 47.Fn readlink 48system call 49places the contents of the symbolic link 50.Fa path 51in the buffer 52.Fa buf , 53which has size 54.Fa bufsiz . 55The 56.Fn readlink 57system call does not append a 58.Dv NUL 59character to 60.Fa buf . 61.Pp 62The 63.Fn readlinkat 64system call is equivalent to 65.Fn readlink 66except in the case where 67.Fa path 68specifies a relative path. 69In this case the symbolic link whose content is read relative to the 70directory associated with the file descriptor 71.Fa fd 72instead of the current working directory. 73If 74.Fn readlinkat 75is passed the special value 76.Dv AT_FDCWD 77in the 78.Fa fd 79parameter, the current working directory is used and the behavior is 80identical to a call to 81.Fn readlink . 82.Sh RETURN VALUES 83The call returns the count of characters placed in the buffer 84if it succeeds, or a \-1 if an error occurs, placing the error 85code in the global variable 86.Va errno . 87.Sh ERRORS 88The 89.Fn readlink 90system call 91will fail if: 92.Bl -tag -width Er 93.It Bq Er ENOTDIR 94A component of the path prefix is not a directory. 95.It Bq Er ENAMETOOLONG 96A component of a pathname exceeded 255 characters, 97or an entire path name exceeded 1023 characters. 98.It Bq Er ENOENT 99The named file does not exist. 100.It Bq Er EACCES 101Search permission is denied for a component of the path prefix. 102.It Bq Er ELOOP 103Too many symbolic links were encountered in translating the pathname. 104.It Bq Er EINVAL 105The named file is not a symbolic link. 106.It Bq Er EIO 107An I/O error occurred while reading from the file system. 108.It Bq Er EINTEGRITY 109Corrupted data was detected while reading from the file system. 110.It Bq Er EFAULT 111The 112.Fa buf 113argument 114extends outside the process's allocated address space. 115.El 116.Pp 117In addition to the errors returned by the 118.Fn readlink , 119the 120.Fn readlinkat 121may fail if: 122.Bl -tag -width Er 123.It Bq Er EBADF 124The 125.Fa path 126argument does not specify an absolute path and the 127.Fa fd 128argument is neither 129.Dv AT_FDCWD 130nor a valid file descriptor open for searching. 131.It Bq Er ENOTDIR 132The 133.Fa path 134argument is not an absolute path and 135.Fa fd 136is neither 137.Dv AT_FDCWD 138nor a file descriptor associated with a directory. 139.El 140.Sh SEE ALSO 141.Xr fhreadlink 2 , 142.Xr lstat 2 , 143.Xr stat 2 , 144.Xr symlink 2 , 145.Xr symlink 7 146.Sh STANDARDS 147The 148.Fn readlinkat 149system call follows The Open Group Extended API Set 2 specification. 150.Sh HISTORY 151The 152.Fn readlink 153system call appeared in 154.Bx 4.2 . 155The 156.Fn readlinkat 157system call appeared in 158.Fx 8.0 . 159