fchown man page

Prolog

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

fchown — change owner and group of a file

Synopsis

#include <unistd.h>

int fchown(int fildes, uid_t owner, gid_t group);

Description

The fchown() function shall be equivalent to chown() except that the file whose owner and group are changed is specified by the file descriptor fildes.

Return Value

Upon successful completion, fchown() shall return 0. Otherwise, it shall return -1 and set errno to indicate the error.

Errors

The fchown() function shall fail if:

EBADF
The fildes argument is not an open file descriptor.
EPERM
The effective user ID does not match the owner of the file or the process does not have appropriate privileges and _POSIX_CHOWN_RESTRICTED indicates that such privilege is required.
EROFS
The file referred to by fildes resides on a read-only file system.

The fchown() function may fail if:

EINVAL
The owner or group ID is not a value supported by the implementation. The fildes argument refers to a pipe or socket or an fattach()-ed STREAM and the implementation disallows execution of fchown() on a pipe.
EIO
A physical I/O error has occurred.
EINTR
The fchown() function was interrupted by a signal which was caught.

The following sections are informative.

Examples

Changing the Current Owner of a File

The following example shows how to change the owner of a file named /home/cnd/mod1 to “jones” and the group to “cnd”.

The numeric value for the user ID is obtained by extracting the user ID from the user database entry associated with “jones”. Similarly, the numeric value for the group ID is obtained by extracting the group ID from the group database entry associated with “cnd”. This example assumes the calling program has appropriate privileges.

#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>

struct passwd *pwd;
struct group  *grp;
int            fildes;
...
fildes = open("/home/cnd/mod1", O_RDWR);
pwd = getpwnam("jones");
grp = getgrnam("cnd");
fchown(fildes, pwd->pw_uid, grp->gr_gid);

See Also

chown()

The Base Definitions volume of POSIX.1‐2008, <unistd.h>

Info

2013 IEEE/The Open Group POSIX Programmer's Manual