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link(2) System Calls Manual link(2) NAME link - Creates an additional directory entry for an existing file on current file system SYNOPSIS #include <unistd.h> int link ( const char *path1, const char *path2 ); STANDARDS Interfaces documented on this reference page conform to industry stan- dards as follows: link(): POSIX.1, XPG4, XPG4-UNIX Refer to the standards(5) reference page for more information about in- dustry standards and associated tags. PARAMETERS Points to the pathname of an existing file. Points to the pathname for the directory entry to be created. If the path2 parameter names a sym- bolic link, an error is returned. DESCRIPTION The link() function creates an additional hard link (directory entry) for an existing file. The old and the new link share equal access rights to the underlying object. The link() function atomically cre- ates a new link for the existing file and increments the link count of the file by one. Both the path1 and path2 parameters must reside on the same file sys- tem. A hard link to a directory cannot be created. Upon successful completion, the link() function marks the st_ctime field of the file for update, and marks the st_ctime and st_mtime fields of the directory containing the new entry for update. A process must have write permission in the target directory with re- spect to all access control policies configured on the system. RETURN VALUES Upon successful completion, the link() function returns a value of 0 (zero). If the link() function fails, a value of -1 is returned, no link is created, and errno is set to indicate the error. ERRORS If the link() function fails, errno may be set to one of the following values: The requested link requires writing in a directory with a mode that denies write permission, or a component of either the path1 or path2 parameter denies search permission. The requested link requires writing in a directory to which the process does not have write access with respect to one or more of the system's configured access policies. The directory in which the entry for the new link is being placed can- not be extended because the user's quota of disk blocks on the file system containing the directory has been exhausted. The link named by the path2 parameter already exists. The path1 or path2 parameter is an invalid address. Too many links were encountered in translating path1 or path2. The number of links to the file named by path1 would exceed LINK_MAX. The length of the path1 or path2 string exceeds PATH_MAX or a pathname component is longer than NAME_MAX. The file named by the path1 parameter does not exist or the path1 or path2 parameter is an empty string. The directory in which the entry for the new link is be- ing placed cannot be extended because there is no space left on the file system containing the directory. A component of either path pre- fix is not a directory. The file named by the path1 parameter is a di- rectory. The requested link requires writing in a directory on a read- only file system. The link named by the path2 parameter and the file named by the path1 parameter are on different file systems. [Digital] For NFS file access, if the link() function fails, errno may also be set to one of the following values: Indicates that the system file table is full or there are too many files currently open in the system. Indicates a stale NFS file handle. An opened file was deleted by the server or another client; a client cannot open a file because the server has unmounted or unexported the remote directory; or the di- rectory that contains an opened file was unmounted or unexported by the server. RELATED INFORMATION Functions: unlink(2) Commands: link(1) Standards: standards(5) delim off link(2)