man lchown () - change the owner and group of a symbolic link

NAME

lchown - change the owner and group of a symbolic link

SYNOPSIS

#include <unistd.h>

int lchown(const char *path, uid_t owner, gid_t group);

DESCRIPTION

The lchown() function shall be equivalent to chown(), except in the case where the named file is a symbolic link. In this case, lchown() shall change the ownership of the symbolic link file itself, while chown() changes the ownership of the file or directory to which the symbolic link refers.

RETURN VALUE

Upon successful completion, lchown() shall return 0. Otherwise, it shall return -1 and set errno to indicate an error.

ERRORS

The lchown() function shall fail if:

EACCES
Search permission is denied on a component of the path prefix of path.
EINVAL
The owner or group ID is not a value supported by the implementation.
ELOOP
A loop exists in symbolic links encountered during resolution of the path argument.
ENAMETOOLONG
The length of a pathname exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.
ENOENT
A component of path does not name an existing file or path is an empty string.
ENOTDIR
A component of the path prefix of path is not a directory.
EOPNOTSUPP
The path argument names a symbolic link and the implementation does not support setting the owner or group of a symbolic link.
EPERM
The effective user ID does not match the owner of the file and the process does not have appropriate privileges.
EROFS
The file resides on a read-only file system.

The lchown() function may fail if:

EIO
An I/O error occurred while reading or writing to the file system.
EINTR
A signal was caught during execution of the function.
ELOOP
More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.
ENAMETOOLONG
Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.

The following sections are informative.

EXAMPLES

Changing the Current Owner of a File

The following example shows how to change the ownership of the symbolic link named /modules/pass1 to the user ID associated with "jones" and the group ID associated with "cnd".

The numeric value for the user ID is obtained by using the getpwnam() function. The numeric value for the group ID is obtained by using the getgrnam() function. 

#include <sys/types.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>


struct passwd *pwd;
struct group  *grp;
char          *path = "/modules/pass1";
...
pwd = getpwnam("jones");
grp = getgrnam("cnd");
lchown(path, pwd->pw_uid, grp->gr_gid);



APPLICATION USAGE

On implementations which support symbolic links as directory entries
rather than files, lchown() may fail.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

chown() , symlink() , the Base Definitions volume of
IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .