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CHOWN(2) | System Calls Manual | CHOWN(2) |
NAME¶
chown
,
fchown
,
lchown
,
fchownat
—
change owner and group of a file
LIBRARY¶
Standard C Library (libc, -lc)SYNOPSIS¶
#include
<unistd.h>
int
chown
(const
char *path,
uid_t owner,
gid_t group);
int
fchown
(int
fd, uid_t
owner, gid_t
group);
int
lchown
(const
char *path,
uid_t owner,
gid_t group);
int
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 path or referenced by fd is changed as specified by the arguments owner and group. The owner of a file may change the group to a group of which he or she is a member, but the change owner capability is restricted to the super-user. Thechown
() 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 chown
() system call
follows symbolic links to operate on the target of the link rather than the
link itself.
The fchown
() system call is particularly
useful when used in conjunction with the file locking primitives (see
flock(2)).
The lchown
() system call is similar to
chown
() but does not follow symbolic links.
The fchownat
() system call is equivalent to
the chown
() and
lchown
() except in the case where
path specifies a relative path. In this case
the file to be changed is determined relative to the directory associated with
the file descriptor fd instead of the current
working directory.
Values for flag are constructed by a
bitwise-inclusive OR of flags from the following list, defined in
<fcntl.h>
:
AT_SYMLINK_NOFOLLOW
- If path names a symbolic link, ownership of the symbolic link is changed.
fchownat
() is passed the special value
AT_FDCWD
in the
fd parameter, the current working directory
is used and the behavior is identical to a call to
chown
() or
lchown
() respectively, depending on whether
or not the AT_SYMLINK_NOFOLLOW
bit is set
in the flag argument.
One of the owner or group id's may be left unchanged by specifying it as -1.
RETURN VALUES¶
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.ERRORS¶
Thechown
() and
lchown
() will fail and the file will be
unchanged if:
- [
ENOTDIR
] - A component of the path prefix is not a directory.
- [
ENAMETOOLONG
] - A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
- [
ENOENT
] - The named file does not exist.
- [
EACCES
] - Search permission is denied for a component of the path prefix.
- [
ELOOP
] - Too many symbolic links were encountered in translating the pathname.
- [
EPERM
] - The operation would change the ownership, but the effective user ID is not the super-user.
- [
EPERM
] - The named file has its immutable or append-only flag set, see the chflags(2) manual page for more information.
- [
EROFS
] - The named file resides on a read-only file system.
- [
EFAULT
] - The path argument points outside the process's allocated address space.
- [
EIO
] - An I/O error occurred while reading from or writing to the file system.
fchown
() system call will fail 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 super-user.
- [
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.
chown
() and
lchown
(), the
fchownat
() system call may fail if:
- [
EBADF
] - The path argument does not specify an
absolute path and the fd argument is
neither
AT_FDCWD
nor a valid file descriptor open for searching. - [
EINVAL
] - The value of the flag argument is not valid.
- [
ENOTDIR
] - The path argument is not an absolute path
and fd is neither
AT_FDCWD
nor a file descriptor associated with a directory.
SEE ALSO¶
chgrp(1), chflags(2), chmod(2), flock(2), chown(8)STANDARDS¶
Thechown
() system call is expected to
conform to IEEE Std 1003.1-1990
(“POSIX.1”). The
fchownat
() system call follows The Open
Group Extended API Set 2 specification.
HISTORY¶
Thechown
() function appeared in
Version 7 AT&T UNIX. The
fchown
() system call appeared in
4.2BSD.
The chown
() system call was changed to follow
symbolic links in 4.4BSD. The
lchown
() system call was added in
FreeBSD 3.0 to compensate for the loss of
functionality.
The fchownat
() system call appeared in
FreeBSD 8.0.April 10, 2008 | Debian |