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.

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

This function is a member of Unison's IOLIB family of functions. IOLIB is implemented as a message passing and generalized interface layer. Each Unison I/O server is responsible for its own error reporting.

For an exact list of error codes returned by a particular server, refer to that server's documentation in the Unison Programmer's Guide for each specific platform.

Servers may implement these errors codes in response to this function.

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

EACCES

A component of either argument denies search permission. Or, 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.

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. Or, a component of either the path prefix or the file named by existing does not exist.

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 either the caller does not have appropriate privileges or the implementation prohibits using link() on directories.

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).

SEE ALSO

unlink()

< Copyright Rowebots Research Inc. and Multiprocessor Toolsmiths Inc. 1987-2011 >