man fchown (2): change owner and group of a file

Other Alias

chown, lchown, fchownat

LIBRARY

Lb libc

SYNOPSIS

In unistd.h Ft int Fn chown const char *path uid_t owner gid_t group Ft int Fn fchown int fd uid_t owner gid_t group Ft int Fn lchown const char *path uid_t owner gid_t group Ft int Fn fchownat int fd const char *path uid_t owner gid_t group int flag

DESCRIPTION

The owner ID and group ID of the file named by Fa path or referenced by Fa fd is changed as specified by the arguments Fa owner and Fa group . The owner of a file may change the Fa group to a group of which he or she is a member, but the change Fa owner capability is restricted to the super-user.

The Fn chown system call clears the set-user-id and set-group-id bits on the file to prevent accidental or mischievous creation of set-user-id and set-group-id programs if not executed by the super-user. The Fn chown system call follows symbolic links to operate on the target of the link rather than the link itself.

The Fn fchown system call is particularly useful when used in conjunction with the file locking primitives (see flock(2)).

The Fn lchown system call is similar to Fn chown but does not follow symbolic links.

The Fn fchownat system call is equivalent to the Fn chown and Fn lchown except in the case where Fa path specifies a relative path. In this case the file to be changed is determined relative to the directory associated with the file descriptor Fa fd instead of the current working directory.

Values for Fa flag are constructed by a bitwise-inclusive OR of flags from the following list, defined in In fcntl.h :

AT_SYMLINK_NOFOLLOW: If Fa path names a symbolic link, ownership of the symbolic link is changed.

If Fn fchownat is passed the special value AT_FDCWD in the Fa fd parameter, the current working directory is used and the behavior is identical to a call to Fn chown or Fn lchown respectively, depending on whether or not the AT_SYMLINK_NOFOLLOW bit is set in the Fa flag argument.

One of the owner or group id's may be left unchanged by specifying it as -1.

RETURN VALUES

Rv -std

ERRORS

The Fn chown and Fn lchown will fail and the file will be unchanged if:

Bq Er ENOTDIR: A component of the path prefix is not a directory.
Bq Er ENAMETOOLONG: A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
Bq Er ENOENT: The named file does not exist.
Bq Er EACCES: Search permission is denied for a component of the path prefix.
Bq Er ELOOP: Too many symbolic links were encountered in translating the pathname.
Bq Er EPERM: The operation would change the ownership, but the effective user ID is not the super-user.
Bq Er EPERM: The named file has its immutable or append-only flag set, see the chflags(2) manual page for more information.
Bq Er EROFS: The named file resides on a read-only file system.
Bq Er EFAULT: The Fa path argument points outside the process's allocated address space.
Bq Er EIO: An I/O error occurred while reading from or writing to the file system.

The Fn fchown system call will fail if:

Bq Er EBADF: The Fa fd argument does not refer to a valid descriptor.
Bq Er EINVAL: The Fa fd argument refers to a socket, not a file.
Bq Er EPERM: The effective user ID is not the super-user.
Bq Er EROFS: The named file resides on a read-only file system.
Bq Er EIO: An I/O error occurred while reading from or writing to the file system.

In addition to the errors specified for Fn chown and Fn lchown , the Fn fchownat system call may fail if:

Bq Er EBADF: The Fa path argument does not specify an absolute path and the Fa fd argument is neither AT_FDCWD nor a valid file descriptor open for searching.
Bq Er EINVAL: The value of the Fa flag argument is not valid.
Bq Er ENOTDIR: The Fa path argument is not an absolute path and Fa fd is neither AT_FDCWD nor a file descriptor associated with a directory.

STANDARDS

The Fn chown system call is expected to conform to St -p1003.1-90 . The Fn fchownat system call follows The Open Group Extended API Set 2 specification.

HISTORY

The Fn chown function appeared in AT&T System v7 . The Fn fchown system call appeared in BSD 4.2

The Fn chown system call was changed to follow symbolic links in BSD 4.4 The Fn lchown system call was added in Fx 3.0 to compensate for the loss of functionality.

The Fn fchownat system call appeared in Fx 8.0 .