LINK(2) MidnightBSD System Calls Manual LINK(2)

NAME

link — make a hard file link

LIBRARY

Standard C Library (libc, −lc)

SYNOPSIS

#include <unistd.h>

int

link(const char *name1, const char *name2);

DESCRIPTION

The link() system call atomically creates the specified directory entry (hard link) name2 with the attributes of the underlying object pointed at by name1. If the link is successful: the link count of the underlying object is incremented; name1 and name2 share equal access and rights to the underlying object.

If name1 is removed, the file name2 is not deleted and the link count of the underlying object is decremented.

The object pointed at by the name1 argument must exist for the hard link to succeed and both name1 and name2 must be in the same file system. The name1 argument may not be a directory.

RETURN VALUES

The link() function returns the value 0 if successful; otherwise the value −1 is returned and the global variable errno is set to indicate the error.

ERRORS

The link() system call will fail and no link will be created if:

[ENOTDIR]

A component of either path prefix is not a directory.

[ENAMETOOLONG]

A component of either pathname exceeded 255 characters, or entire length of either path name exceeded 1023 characters.

[ENOENT]

A component of either path prefix does not exist.

[EOPNOTSUPP]

The file system containing the file named by name1 does not support links.

[EMLINK]

The link count of the file named by name1 would exceed 32767.

[EACCES]

A component of either path prefix denies search permission.

[EACCES]

The requested link requires writing in a directory with a mode that denies write permission.

[ELOOP]

Too many symbolic links were encountered in translating one of the pathnames.

[ENOENT]

The file named by name1 does not exist.

[EEXIST]

The link named by name2 does exist.

[EPERM]

The file named by name1 is a directory.

[EPERM]

The file named by name1 has its immutable or append-only flag set, see the chflags(2) manual page for more information.

[EPERM]

The parent directory of the file named by name2 has its immutable flag set.

[EXDEV]

The link named by name2 and the file named by name1 are on different file systems.

[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.

[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.

[EIO]

An I/O error occurred while reading from or writing to the file system to make the directory entry.

[EROFS]

The requested link requires writing in a directory on a read-only file system.

[EFAULT]

One of the pathnames specified is outside the process’s allocated address space.

SEE ALSO

chflags(2), readlink(2), symlink(2), unlink(2)

STANDARDS

The link() system call is expected to conform to ISO/IEC 9945-1:1990 (‘‘POSIX.1’’).

HISTORY

The link() function appeared in Version 7 AT&T UNIX.

The link() system call traditionally allows the super-user to link directories which corrupts the file system coherency. This implementation no longer permits it.

MidnightBSD 0.3 December 9, 2006 MidnightBSD 0.3