link(2)

NAME

link − link to a file

SYNOPSIS

#include <unistd.h>

int link(const char ∗existing, const char ∗new);

DESCRIPTION

link() creates a new link (directory entry) for the existing file and increments its link count by one. existing points to a path name naming an existing file. new points to a path name naming the new directory entry to be created.

To create hard links, both files must be on the same file system. Both the old and the new link share equal access and rights to the underlying object. The super-user may make multiple links to a directory. Unless the caller is the super-user, the file named by existing must not be a directory.

Upon successful completion, link() marks for update the st_ctime field of the file. Also, the st_ctime and st_mtime fields of the directory that contains the new entry are marked for update.

RETURN VALUES

Upon successful completion, a value of 0 is returned. Otherwise, a value of −1 is returned and errno is set to indicate the error.

ERRORS

link() will fail and no link will be created if one or more of the following are true:

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.

EEXIST The link named by new exists.

EFAULT existing or new points to an illegal address.

EINTR A signal was caught during the link() function.

ELOOP Too many symbolic links were encountered in translating path.

EMLINK The maximum number of links to a file would be exceeded.

EMULTIHOP Components of existing or new require hopping to multiple remote machines and the file system type does not allow it.

ENAMETOOLONG
The length of the existing or new argument exceeds {PATH_MAX}, or the length of a existing or new component exceeds {NAME_MAX} while {_POSIX_NO_TRUNC} is in effect.

ENOENT existing or new is a null path name.

ENOENT A component of either path prefix does not exist.

ENOENT The file named by existing does not exist.

ENOLINK existing or new points to a remote machine and the link to that machine is no longer active.

ENOSPC the directory that would contain the link cannot be extended.

ENOTDIR A component of either path prefix is not a directory.

EPERM The file named by existing is a directory and the effective user of the calling process is not super-user.

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

EXDEV The link named by new and the file named by existing are on different logical devices (file systems).

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