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.\" 30.Dd March 30, 2020 31.Dt READLINK 2 32.Os 33.Sh NAME 34.Nm readlink , 35.Nm readlinkat 36.Nd read value of a symbolic link 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In unistd.h 41.Ft ssize_t 42.Fn readlink "const char *restrict path" "char *restrict buf" "size_t bufsiz" 43.Ft ssize_t 44.Fo readlinkat 45.Fa "int fd" "const char *restrict path" "char *restrict buf" "size_t bufsize" 46.Fc 47.Sh DESCRIPTION 48The 49.Fn readlink 50system call 51places the contents of the symbolic link 52.Fa path 53in the buffer 54.Fa buf , 55which has size 56.Fa bufsiz . 57The 58.Fn readlink 59system call does not append a 60.Dv NUL 61character to 62.Fa buf . 63.Pp 64The 65.Fn readlinkat 66system call is equivalent to 67.Fn readlink 68except in the case where 69.Fa path 70specifies a relative path. 71In this case the symbolic link whose content is read relative to the 72directory associated with the file descriptor 73.Fa fd 74instead of the current working directory. 75If 76.Fn readlinkat 77is passed the special value 78.Dv AT_FDCWD 79in the 80.Fa fd 81parameter, the current working directory is used and the behavior is 82identical to a call to 83.Fn readlink . 84.Sh RETURN VALUES 85The call returns the count of characters placed in the buffer 86if it succeeds, or a \-1 if an error occurs, placing the error 87code in the global variable 88.Va errno . 89.Sh ERRORS 90The 91.Fn readlink 92system call 93will fail if: 94.Bl -tag -width Er 95.It Bq Er ENOTDIR 96A component of the path prefix is not a directory. 97.It Bq Er ENAMETOOLONG 98A component of a pathname exceeded 255 characters, 99or an entire path name exceeded 1023 characters. 100.It Bq Er ENOENT 101The named file does not exist. 102.It Bq Er EACCES 103Search permission is denied for a component of the path prefix. 104.It Bq Er ELOOP 105Too many symbolic links were encountered in translating the pathname. 106.It Bq Er EINVAL 107The named file is not a symbolic link. 108.It Bq Er EIO 109An I/O error occurred while reading from the file system. 110.It Bq Er EINTEGRITY 111Corrupted data was detected while reading from the file system. 112.It Bq Er EFAULT 113The 114.Fa buf 115argument 116extends outside the process's allocated address space. 117.El 118.Pp 119In addition to the errors returned by the 120.Fn readlink , 121the 122.Fn readlinkat 123may fail if: 124.Bl -tag -width Er 125.It Bq Er EBADF 126The 127.Fa path 128argument does not specify an absolute path and the 129.Fa fd 130argument is neither 131.Dv AT_FDCWD 132nor a valid file descriptor open for searching. 133.It Bq Er ENOTDIR 134The 135.Fa path 136argument is not an absolute path and 137.Fa fd 138is neither 139.Dv AT_FDCWD 140nor a file descriptor associated with a directory. 141.El 142.Sh SEE ALSO 143.Xr lstat 2 , 144.Xr stat 2 , 145.Xr symlink 2 , 146.Xr symlink 7 147.Sh STANDARDS 148The 149.Fn readlinkat 150system call follows The Open Group Extended API Set 2 specification. 151.Sh HISTORY 152The 153.Fn readlink 154system call appeared in 155.Bx 4.2 . 156The 157.Fn readlinkat 158system call appeared in 159.Fx 8.0 . 160