CHOWN(2)

NAME
chown, fchown - change ownership of a file

SYNOPSIS
#include <sys/types.h>
#include <unistd.h>

int chown(const char *path, uid_t owner, gid_t group);
int fchown(int fd, uid_t owner, gid_t group);

DESCRIPTION
The owner of the file specified by path or by fd is changed. Only the super-user may change the owner of a file. The owner of a file may change the group of the file to any group of which that owner is a member. The super-user may change the group arbitrarily. If the owner or group is specified as -1, then that ID is not changed.

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

ERRORS
Depending on the file system, other errors can be returned. The more general errors for chown are listed below:

EPERM
    The effective UID does not match the owner of the file, and is not zero; or the owner or group were specified incorrectly.

EROFS
    The named file resides on a read-only file system.

EFAULT
    path points outside your accessible address space.

ENAMETOOLONG
    path is too long.

ENOENT
    The file does not exist.

ENOMEM
    Insufficient kernel memory was available.

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

EACCES
    Search permission is denied on a component of the path prefix.

ELOOP
    Too many symbolic links were encountered in resolving path.

The general errors for fchown are listed below:

EBADF
    The descriptor is not valid.

ENOENT
    See above.

EPERM
    See above.

EROFS
    See above. EIO A low-level I/O error occurred while modifying the inode.

NOTES
chown does not follow symbolic links. The prototype for fchown is only available if __USE_BSD is defined.

CONFORMING TO
The chown call conforms to SVr4, SVID, POSIX, X/OPEN. The 4.4BSD version can only be usaed by the superuser (that is, ordinary users cannot give away files). SVr4 documents EINVAL, EINTR, ENOLINK and EMULTIHOP returns, but no ENOMEM. POSIX.1 does not document ENOMEM or ELOOP error conditions.

The fchown call conforms to 4.4BSD and SVr4. SVr4 documents additional EINVAL, EIO, EINTR, and ENOLINK error conditions.

RESTRICTIONS
The chown() semantics are deliberately violated on NFS file systems which have UID mapping enabled. Additionally, the semantics of all system calls which access the file contents are violated, because chown() may cause immediate access revocation on already open files. Client side caching may lead to a delay between the time where ownership have been changed to allow access for a user and the time where the file can actually be accessed by the user on other clients.

SEE ALSO
chmod(2), flock(2)