chown(2)chown(2)Name
chown, fchown - change owner and group of a file
Syntax
#include <sys/types.h>
chown(path, owner, group)
char *path;
uid_t owner;
gid_t group;
fchown(fd, owner, group)
int fd;
uid_t owner;
gid_t group;
Description
The and system calls change the owner and group of the file named by
path or referenced by fd . Only the superuser can change the owner of
a file. Other users can change the group-id of a file that they own to
another group to which they belong.
If you specify -1 in owner or group, the corresponding owner-id or
group-id of the file is unchanged.
The system call clears the set-user-id and set-group-id bits on the
file when it returns successfully, unless the call is made by the supe‐
ruser. Clearing these bits when a file's owner is changed protects the
file from remaining set-user-id or set-group-id after being modified.
If a file, specifically a program, remained set-user-id or set-group-id
after being modified, that file could allow unauthorized access to
other files or accounts.
You should use the system call with the file locking primitives because
preserves any locks you previously obtained with the system call. For
more information about file locking, see the reference page.
Return Values
The and calls return zero if the operation is successful; if an error
occurs they return -1 and store a more specific error code in the
global variable errno.
Environment
System Five
Differs from the System V definition in that only the superuser can
change the ownership of a file. In addition, ELOOP is a possible error
condition.
POSIX
When your program is compiled in the POSIX environment, the owner argu‐
ment is of type uid_t, and the group argument is of type gid_t.
Diagnostics
The system call fails and the file is unchanged under the following
conditions:
[ENOTDIR] A component of the path prefix is not a directory.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an
entire pathname exceeded 1023 characters.
[ENOENT] The named file does not exist.
[EACCES] Search permission is denied for a component of the path
prefix.
[EPERM] The effective user-id is not the superuser.
[EROFS] The named file resides on a read-only file system.
[EFAULT] The pathname points outside the process's allocated
address space.
[ELOOP] Too many symbolic links are encountered in translating
the pathname.
[EIO] An I/O error occurs while reading from or writing to the
file system.
[ESTALE] The fd argument is invalid because the file referred to
by that file handle no longer exists or has been
revoked.
The system call fails if:
[EBADF] The fd argument does not refer to a valid descriptor.
[EINVAL] The fd argument refers to a socket, not a file.
[EPERM] The effective user-id is not the superuser.
[EROFS] The named file resides on a read-only file system.
[EIO] An I/O error occurred while reading from or writing to
the file system.
[ETIMEDOUT] A connect request or remote file operation fails because
the connected party does not properly respond after a
period of time that is dependent on the communications
protocol.
See Alsochmod(2), flock(2)chown(2)
