IEEE/The Open Group
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
int fchown(int fildes, uid_t owner, gid_t group);
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.
Upon successful completion, fchown() shall return 0. Otherwise, it shall return -1 and set errno to indicate the error.
The fchown() function shall fail if:
The following sections are informative.
|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.|
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);
The Base Definitions volume of POSIX.1-2008, <unistd.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.unix.org/online.html .
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