bsd/man/man2/link.2

   1 .\"     $NetBSD: link.2,v 1.7 1995/02/27 12:34:01 cgd Exp $
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  34 .\"     @(#)link.2      8.3 (Berkeley) 1/12/94
  35 .\"
  36 .Dd October 29, 2008
  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 .Pp
  85 .Fn link
  86 will resolve and follow symbolic links contained within both
  87 .Fa path1
  88 and
  89 .Fa path2 .
  90 If the last component of
  91 .Fa path1
  92 is a symbolic link,
  93 .Fn link
  94 will point the hard link,
  95 .Fa path2 ,
  96 to the underlying object pointed to by
  97 .Fa path1 ,
  98 not to the symbolic link itself.
  99 .Sh RETURN VALUES
 100 Upon successful completion, a value of 0 is returned.  Otherwise,
 101 a value of -1 is returned and
 102 .Va errno
 103 is set to indicate the error.
 104 .Sh ERRORS
 105 .Fn Link
 106 will fail and no link will be created if:
 107 .Bl -tag -width Er
 108 .\" ==========
 109 .It Bq Er EACCES
 110 A component of either path prefix denies search permission.
 111 .\" ==========
 112 .It Bq Er EACCES
 113 The requested link requires writing in a directory with a mode
 114 that denies write permission.
 115 .\" ==========
 116 .It Bq Er EACCES
 117 The current process cannot access the existing file.
 118 .\" ==========
 119 .It Bq Er EDQUOT
 120 The directory in which the entry for the new link
 121 is being placed cannot be extended because the
 122 user's quota of disk blocks on the file system
 123 containing the directory has been exhausted.
 124 .\" ==========
 125 .It Bq Er EEXIST
 126 The link named by
 127 .Fa path2
 128 already exists.
 129 .\" ==========
 130 .It Bq Er EFAULT
 131 One of the pathnames specified
 132 is outside the process's allocated address space.
 133 .\" ==========
 134 .It Bq Er EIO
 135 An I/O error occurs while reading from or writing to
 136 the file system to make the directory entry.
 137 .\" ==========
 138 .It Bq Er ELOOP
 139 Too many symbolic links are encountered in translating one of the pathnames.
 140 This is taken to be indicative of a looping symbolic link.
 141 .\" ==========
 142 .It Bq Er EMLINK
 143 The file already has {LINK_MAX} links.
 144 .\" ==========
 145 .It Bq Er ENAMETOOLONG
 146 A component of a pathname exceeds
 147 .Dv {NAME_MAX}
 148 characters, or an entire path name exceeded
 149 .Dv {PATH_MAX}
 150 characters.
 151 .\" ==========
 152 .It Bq Er ENOENT
 153 A component of either path prefix does not exist, or is a dangling symbolic link.
 154 .\" ==========
 155 .It Bq Er ENOENT
 156 The file named by
 157 .Fa path1
 158 does not exist, or is a dangling symbolic link.
 159 .\" ==========
 160 .It Bq Er ENOSPC
 161 The directory in which the entry for the new link is being placed
 162 cannot be extended because there is no space left on the file
 163 system containing the directory.
 164 .\" ==========
 165 .It Bq Er ENOTDIR
 166 A component of either path prefix is not a directory.
 167 .\" ==========
 168 .It Bq Er EPERM
 169 The file named by
 170 .Fa path1
 171 is a directory.
 172 .\" ==========
 173 .It Bq Er EROFS
 174 The requested link requires writing in a directory
 175 on a read-only file system.
 176 .\" ==========
 177 .It Bq Er EXDEV
 178 The link named by
 179 .Fa path2
 180 and the file named by
 181 .Fa path1
 182 are on different file systems.
 183 .El
 184 .Sh SEE ALSO
 185 .Xr symlink 2 ,
 186 .Xr unlink 2
 187 .Sh STANDARDS
 188 The
 189 .Fn link
 190 function is expected to conform to
 191 .St -p1003.1-88 .