bsd/man/man2/link.2

   1 .\"     $NetBSD: link.2,v 1.7 1995/02/27 12:34:01 cgd Exp $
   2 .\"
   3 .\" Copyright (c) 1980, 1991, 1993
   4 .\"     The Regents of the University of California.  All rights reserved.
   5 .\"
   6 .\" Redistribution and use in source and binary forms, with or without
   7 .\" modification, are permitted provided that the following conditions
   8 .\" are met:
   9 .\" 1. Redistributions of source code must retain the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer.
  11 .\" 2. Redistributions in binary form must reproduce the above copyright
  12 .\"    notice, this list of conditions and the following disclaimer in the
  13 .\"    documentation and/or other materials provided with the distribution.
  14 .\" 3. All advertising materials mentioning features or use of this software
  15 .\"    must display the following acknowledgement:
  16 .\"     This product includes software developed by the University of
  17 .\"     California, Berkeley and its contributors.
  18 .\" 4. Neither the name of the University nor the names of its contributors
  19 .\"    may be used to endorse or promote products derived from this software
  20 .\"    without specific prior written permission.
  21 .\"
  22 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32 .\" SUCH DAMAGE.
  33 .\"
  34 .\"     @(#)link.2      8.3 (Berkeley) 1/12/94
  35 .\"
  36 .Dd January 12, 1994
  37 .Dt LINK 2
  38 .Os BSD 4
  39 .Sh NAME
  40 .Nm link
  41 .Nd make a hard file link
  42 .Sh SYNOPSIS
  43 .Fd #include <unistd.h>
  44 .Ft int
  45 .Fo link
  46 .Fa "const char *path1"
  47 .Fa "const char *path2"
  48 .Fc
  49 .Sh DESCRIPTION
  50 The
  51 .Fn link
  52 function call
  53 atomically creates the specified directory entry (hard link)
  54 .Fa path2
  55 with the attributes of the underlying object pointed at by
  56 .Fa path1 .
  57 If the link is successful,
  58 the link count of the underlying object is incremented;
  59 .Fa path1
  60 and
  61 .Fa path2
  62 share equal access and rights
  63 to the
  64 underlying object.
  65 .Pp
  66 If
  67 .Fa path1
  68 is removed, the file
  69 .Fa path2
  70 is not deleted and the link count of the
  71 underlying object is
  72 decremented.
  73 .Pp
  74 In order for the system call to succeed,
  75 .Fa path1
  76 must exist and both
  77 .Fa path1
  78 and
  79 .Fa path2
  80 must be in the same file system.
  81 As mandated by POSIX.1,
  82 .Fa path1
  83 may not be a directory.
  84 .Sh RETURN VALUES
  85 Upon successful completion, a value of 0 is returned.  Otherwise,
  86 a value of -1 is returned and
  87 .Va errno
  88 is set to indicate the error.
  89 .Sh ERRORS
  90 .Fn Link
  91 will fail and no link will be created if:
  92 .Bl -tag -width Er
  93 .\" ==========
  94 .It Bq Er EACCES
  95 A component of either path prefix denies search permission.
  96 .\" ==========
  97 .It Bq Er EACCES
  98 The requested link requires writing in a directory with a mode
  99 that denies write permission.
 100 .\" ==========
 101 .It Bq Er EACCES
 102 The current process cannot access the existing file.
 103 .\" ==========
 104 .It Bq Er EDQUOT
 105 The directory in which the entry for the new link
 106 is being placed cannot be extended because the
 107 user's quota of disk blocks on the file system
 108 containing the directory has been exhausted.
 109 .\" ==========
 110 .It Bq Er EEXIST
 111 The link named by
 112 .Fa path2
 113 already exists.
 114 .\" ==========
 115 .It Bq Er EFAULT
 116 One of the pathnames specified
 117 is outside the process's allocated address space.
 118 .\" ==========
 119 .It Bq Er EIO
 120 An I/O error occurs while reading from or writing to
 121 the file system to make the directory entry.
 122 .\" ==========
 123 .It Bq Er ELOOP
 124 Too many symbolic links are encountered in translating one of the pathnames.
 125 This is taken to be indicative of a looping symbolic link.
 126 .\" ==========
 127 .It Bq Er EMLINK
 128 The file already has {LINK_MAX} links.
 129 .\" ==========
 130 .It Bq Er ENAMETOOLONG
 131 A component of a pathname exceeds
 132 .Dv {NAME_MAX}
 133 characters, or an entire path name exceeded
 134 .Dv {PATH_MAX}
 135 characters.
 136 .\" ==========
 137 .It Bq Er ENOENT
 138 A component of either path prefix does not exist.
 139 .\" ==========
 140 .It Bq Er ENOENT
 141 The file named by
 142 .Fa path1
 143 does not exist.
 144 .\" ==========
 145 .It Bq Er ENOSPC
 146 The directory in which the entry for the new link is being placed
 147 cannot be extended because there is no space left on the file
 148 system containing the directory.
 149 .\" ==========
 150 .It Bq Er ENOTDIR
 151 A component of either path prefix is not a directory.
 152 .\" ==========
 153 .It Bq Er EPERM
 154 The file named by
 155 .Fa path1
 156 is a directory.
 157 .\" ==========
 158 .It Bq Er EROFS
 159 The requested link requires writing in a directory
 160 on a read-only file system.
 161 .\" ==========
 162 .It Bq Er EXDEV
 163 The link named by
 164 .Fa path2
 165 and the file named by
 166 .Fa path1
 167 are on different file systems.
 168 .El
 169 .Sh SEE ALSO
 170 .Xr symlink 2 ,
 171 .Xr unlink 2
 172 .Sh STANDARDS
 173 The
 174 .Fn link
 175 function is expected to conform to
 176 .St -p1003.1-88 .