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lib/libc/sys/link.2
268 строк
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millert
The source of a link (name1) may not be a directory.
18 июл 2024, 18:38
18 июл 2024, 18:38
070ee79
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.\" $OpenBSD: link.2,v 1.31 2024/07/18 15:38:57 millert Exp $ .\" $NetBSD: link.2,v 1.7 1995/02/27 12:34:01 cgd Exp $ .\" .\" Copyright (c) 1980, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)link.2 8.3 (Berkeley) 1/12/94 .\" .Dd $Mdocdate: July 18 2024 $ .Dt LINK 2 .Os .Sh NAME .Nm link , .Nm linkat .Nd make hard link to a file .Sh SYNOPSIS .In unistd.h .Ft int .Fn link "const char *name1" "const char *name2" .In fcntl.h .In unistd.h .Ft int .Fn linkat "int fd1" "const char *name1" "int fd2" "const char *name2" "int flag" .Sh DESCRIPTION The .Fn link function atomically creates the specified directory entry (hard link) .Fa name2 with the attributes of the underlying object pointed at by .Fa name1 . If the link is successful: the link count of the underlying object is incremented; .Fa name1 and .Fa name2 share equal access and rights to the underlying object. .Pp If .Fa name1 is removed, the file .Fa name2 is not deleted and the link count of the underlying object is decremented. .Pp For the hard link to succeed, .Fa name1 must exist and not be a directory, and both .Fa name1 and .Fa name2 must be in the same file system. .Pp The .Fn linkat function is equivalent to .Fn link except that where .Fa name1 or .Fa name2 specifies a relative path, the directory entries linked are resolved relative to the directories associated with file descriptors .Fa fd1 or .Fa fd2 (respectively) instead of the current working directory. .Pp If .Fn linkat is passed the special value .Dv AT_FDCWD (defined in .In fcntl.h ) in the .Fa fd1 or .Fa fd2 parameter, the current working directory is used for resolving the respective .Fa name1 or .Fa name2 argument. .Pp The .Fa flag argument is the bitwise OR of zero or more of the following values: .Pp .Bl -tag -width AT_SYMLINK_FOLLOW -offset indent -compact .It Dv AT_SYMLINK_FOLLOW If .Fa name1 names a symbolic link, a new link for the target of the symbolic link is created. .El .Pp If the .Dv AT_SYMLINK_FOLLOW flag is clear and .Fa name1 names a symbolic link, a new link is created for the symbolic link .Fa name1 and not its target. .Sh RETURN VALUES .Rv -std .Sh ERRORS .Fn link and .Fn linkat will fail and no link will be created if: .Bl -tag -width Er .It Bq Er ENOTDIR A component of either path prefix is not a directory. .It Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv NAME_MAX characters, or an entire pathname (including the terminating NUL) exceeded .Dv PATH_MAX bytes. .It Bq Er ENOENT A component of either path prefix does not exist. .It Bq Er EOPNOTSUPP The file system containing the file named by .Fa name1 does not support links. .It Bq Er EMLINK The link count of the file named by .Fa name1 would exceed .Dv LINK_MAX . .It Bq Er EACCES A component of either path prefix denies search permission. .It Bq Er EACCES The requested link requires writing in a directory with a mode that denies write permission. .It Bq Er ELOOP Too many symbolic links were encountered in translating one of the pathnames. .It Bq Er ENOENT The file named by .Fa name1 does not exist. .It Bq Er EEXIST The link named by .Fa name2 does exist. .It Bq Er EPERM The file named by .Fa name1 is a directory. .It Bq Er EPERM The file named by .Fa name1 is flagged immutable or append-only. .It Bq Er EXDEV The link named by .Fa name2 and the file named by .Fa name1 are on different file systems. .It Bq Er ENOSPC The directory in which the entry for the new link is being placed cannot be extended because there is no space left on the file system containing the directory. .It Bq Er EDQUOT The directory in which the entry for the new link is being placed cannot be extended because the user's quota of disk blocks on the file system containing the directory has been exhausted. .It Bq Er EIO An I/O error occurred while reading from or writing to the file system to make the directory entry. .It Bq Er EROFS The requested link requires writing in a directory on a read-only file system. .It Bq Er EFAULT One of the pathnames specified is outside the process's allocated address space. .El .Pp Additionally, .Fn linkat will fail if: .Bl -tag -width Er .It Bq Er EINVAL The value of the .Fa flag argument was neither zero nor .Dv AT_SYMLINK_FOLLOW . .It Bq Er EBADF The .Fa name1 or .Fa name2 argument specifies a relative path and the .Fa fd1 or .Fa fd2 argument, respectively, is neither .Dv AT_FDCWD nor a valid file descriptor. .It Bq Er ENOTDIR The .Fa name1 or .Fa name2 argument specifies a relative path and the .Fa fd1 or .Fa fd2 argument, respectively, is a valid file descriptor but it does not reference a directory. .It Bq Er EACCES The .Fa name1 or .Fa name2 argument specifies a relative path but search permission is denied for the directory which the .Fa fd1 or .Fa fd2 file descriptor, respectively, references. .El .Sh SEE ALSO .Xr ln 1 , .Xr readlink 2 , .Xr symlink 2 , .Xr unlink 2 .Sh STANDARDS The .Fn link and .Fn linkat functions are expected to conform to .St -p1003.1-2008 . .Sh HISTORY The .Fn link system call first appeared in .At v1 . The .Fn linkat function appeared in .Ox 5.0 .