link - 爲一個文件的起新名稱

內容簡介

#include <unistd.h>

int link(const char **oldpath*, const char **newpath*);

描述

link () 創建一個新的鏈接（也稱爲硬鏈接）到現有文件中。

If newpath exists it will not be overwritten.

This new name may be used exactly as the old one for any operation; both names refer to the same file (and so have the same permissions and ownership) and it is impossible to tell which name was the `original’.

返回值

On success, zero is returned. On error, -1 is returned, and  errno  is set appropriately.

錯誤

標籤

描述

EACCES

Write access to the directory containing newpath is denied, or search permission is denied for one of the directories in the path prefix of oldpath or newpath. (See also path_resolution(2).)

EEXIST

newpath already exists.

EFAULT

oldpath or newpath yiibais outside your accessible address space.

EIO

An I/O error occurred.

ELOOP

Too many symbolic links were encountered in resolving oldpathor newpath.

EMLINK

The file referred to by oldpath already has the maximum number of links to it.

ENAMETOOLONG

 

oldpath or newpath was too long.

ENOENT

A directory component in oldpath or newpath does not exist or is a dangling symbolic link.

ENOMEM

Insufficient kernel memory was available.

ENOSPC

The device containing the file has no room for the new directory entry.

ENOTDIR

 

A component used as a directory in oldpath or newpath is not, in fact, a directory.

EPERM

oldpath is a directory.

EPERM

The filesystem containing oldpath and newpath does not support the creation of hard links.

EROFS

The file is on a read-only filesystem.

EXDEV

oldpath and newpath are not on the same mounted filesystem. (Linux permits a filesystem to be mounted at multiple yiibais, butlink(2) does not work across different mount yiibais, even if the same filesystem is mounted on both.)

注意

Hard links, as created by  link (), cannot span filesystems. Use  symlink () if this is required.

POSIX.1-2001 says that link() should dereference oldpath if it is a symbolic link. However, Linux does not do so: if oldpath is a symbolic link, then newpath is created as a (hard) link to the same symbolic link file (i.e., newpath becomes a symbolic link to the same file that oldpath refers to). Some other implementations behave in the same manner as Linux.

遵循於

SVr4, 4.3BSD, POSIX.1-2001 (except as noted above).

BUGS

On NFS file systems, the return code may be wrong in case the NFS server performs the link creation and dies before it can say so. Use  stat (2) to find out if the link got created.

另請參閱

• ln (1)

• linkat (2)

• open (2)

• path_resolution (2)

• rename (2)

• stat (2)

• symlink (2)

• unlink (2)