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Manual page for CHOWN(2V)

chown, fchown - change owner and group of a file

SYNOPSIS

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

SYSTEM V SYNOPSIS

#include <sys/types.h>
int chown(path, owner, group)
char *path;
uid_t owner;
gid_t group;

DESCRIPTION

The file that is named by path or referenced by fd has its owner and group changed as specified. Only the super-user may change the owner of the file, because if users were able to give files away, they could defeat the file-space accounting procedures (see NOTES). The owner of the file may change the group to a group of which he is a member. The super-user may change the group arbitrarily.

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

If owner or group is specified as -1, the corresponding ID of the file is not changed.

If a process whose effective user ID is not super-user successfully changes the group ID of a file, the set-user-ID and set-group-ID bits of the file mode, S_ISUID and S_ISGID respectively (see stat.2v will be cleared.

If the final component of path is a symbolic link, the ownership and group of the symbolic link is changed, not the ownership and group of the file or directory to which it points.

RETURN VALUES

chown() and fchown() return:

0: on success.
-1: on failure and set errno to indicate the error.

ERRORS

chown() will fail and the file will be unchanged if:

EACCES: Search permission is denied for a component of the path prefix of path.
EFAULT: path points outside the process's allocated address space.
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.
ENAMETOOLONG: The length of the path argument exceeds {PATH_MAX}.
: A pathname component is longer than {NAME_MAX} (see sysconf.2v while {_POSIX_NO_TRUNC} is in effect (see pathconf.2v
ENOENT: The file referred to by path does not exist.
ENOTDIR: A component of the path prefix of path is not a directory.
EPERM: The user ID specified by owner is not the current owner ID of the file
: The group ID specified by group is not the current group ID of the file and is not in the process' supplementary group IDs, and the effective user ID is not the super-user.
EROFS: The file referred to by path resides on a read-only file system.

fchown() will fail if:

EBADF: fd does not refer to a valid descriptor.
EINVAL: fd refers to a socket, not a file.
EIO: An I/O error occurred while reading from or writing to the file system.
EPERM: The user ID specified by owner is not the current owner ID of the file.
: The group ID specified by group is not the current group ID of the file and is not in the supplementary group IDs, and the effective user ID is not the super-user.
EROFS: The file referred to by fd resides on a read-only file system.

SYSTEM V ERRORS

In addition to the above, the following may also occur:

ENOENT: path points to an empty string.

NOTES

For chown() to behave as described above, {_POSIX_CHOWN_RESTRICTED} must be in effect (see pathconf.2v {_POSIX_CHOWN_RESTRICTED} is always in effect on SunOS systems, but for portability, applications should call pathconf() to determine whether {_POSIX_CHOWN_RESTRICTED} is in effect for path.

If {_POSIX_CHOWN_RESTRICTED} is in effect for the file system on which the file referred to by path or fd resides, only the super-user may change the owner of the file. Otherwise, processes with effective user ID equal to the file owner or super-user may change the owner of the file.