chown(2) manual page
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chown, lchown, fchown - change owner and group of a file
#include <unistd.h>
#include <sys/types.h>
int chown(const char *path, uid_t owner, gid_t group);
int lchown(const
char *path, uid_t owner, gid_t group);
int fchown(int fildes, uid_t owner,
gid_t group);
chown() is Async-Signal-Safe
.B chown()
sets the owner ID
and group ID
of the file specified by path or referenced
by the open file descriptor fildes to owner and group respectively. If owner
or group is specified as -1, chown() does not change the corresponding ID
of the file.
The function lchown() sets the owner ID
and group ID
of the
named file just as chown() does, except in the case where the named file
is a symbolic link. In this case, lchown() changes the ownership of the
symbolic link file itself, while chown() changes the ownership of the
file or directory to which the symbolic link refers.
If chown(), lchown(),
or fchown() is invoked by a process other than super-user, the set-user-ID
and set-group-ID
bits of the file mode, S_ISUID and S_ISGID respectively,
are cleared (see chmod(2)
).
The operating system has a configuration option,
{_POSIX_CHOWN_RESTRICTED}, to restrict ownership changes for the chown(),
lchown(), and fchown() functions. When {_POSIX_CHOWN_RESTRICTED} is not
in effect, the effective user ID
of the process must match the owner of
the file or the process must be the super-user to change the ownership
of a file. When {_POSIX_CHOWN_RESTRICTED} is in effect, the chown(), lchown(),
and fchown() functions, for users other than super-user, prevent the owner
of the file from changing the owner ID
of the file and restrict the change
of the group of the file to the list of supplementary group ID
s.
Upon successful
completion, chown(), fchown() and lchown() mark for update the st_ctime
field of the file.
Upon successful completion, a value of 0
is returned. Otherwise, a value of -1 is returned and errno is set to indicate
the error.
chown() and lchown() fail and the owner and group of the
named file remain unchanged if one or more of the following are true:
- EACCES
- Search permission is denied on a component of the path prefix of path.
- EFAULT
- path points to an illegal address.
- EINTR
- A signal was caught during
the chown() or lchown() functions.
- EINVAL
- group or owner is out of range.
- EIO
- An I/O error occurred while reading from or writing to the file system.
- ELOOP
- Too many symbolic links were encountered in translating path.
- EMULTIHOP
- Components of path require hopping to multiple remote machines and file
system type does not allow it. Too many symbolic links were encountered
in translating path.
- ENAMETOOLONG
- The length of the path argument exceeds
{PATH_MAX}, or the length of a path component exceeds {NAME_MAX} while
{_POSIX_NO_TRUNC} is in effect.
- ENOLINK
- path points to a remote machine
and the link to that machine is no longer active.
- ENOENT
- Either a component
of the path prefix or the file referred to by path does not exist or is
a null pathname.
- ENOTDIR
- A component of the path prefix of path is not
a directory.
- EPERM
- The effective user ID
does not match the owner of the
file or the process is not the super-user and {_POSIX_CHOWN_RESTRICTED}
indicates that such privilege is required.
- EROFS
- The named file resides
on a read-only file system.
fchown() fails and the owner and group of the
named file remain unchanged if one or more of the following are true:
- EBADF
- fildes is not an open file descriptor.
- EIO
- An I/O error occurred while
reading from or writing to the file system.
- EINTR
- A signal was caught during
execution of the function.
- ENOLINK
- fildes points to a remote machine and
the link to that machine is no longer active.
- EINVAL
- group or owner is
out of range.
- EPERM
- The effective user ID
does not match the owner of the
file or the process is not the super-user and {_POSIX_CHOWN_RESTRICTED}
indicates that such privilege is required.
- EROFS
- The named file referred
to by fildes resides on a read-only file system.
chgrp(1)
, chown(1)
,
chmod(2)
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