#include <sys/types.h> /* For uid_t and gid_t / #include <unistd.h> / for fchown prototype */
The owner of the file specified by fd is changed. Only the super-user may change the owner of a file. The owner of a file may change the group of the file to any group of which that owner is a member. The super-user may change the group arbitrarily.
If the owner or group is specified as -1, then that ID is not changed.
When the owner or group of an executable file are changed by a non-super-user, the S_ISUID and S_ISGID mode bits are cleared. POSIX does not specify whether this also should happen when root does the chown; the Linux behaviour depends on the kernel version. In case of a non-group-executable file (with clear S_IXGRP bit) the S_ISGID bit indicates mandatory locking, and is not cleared by a chown.
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
Depending on the file system, other errors can be returned.
The prototype for fchown is only available if _BSD_SOURCE is defined (either explicitly, or implicitly, by not defining _POSIX_SOURCE or compiling with the -ansi flag).
The fchown(2) semantics are deliberately violated on NFS file systems which have UID mapping enabled. Additionally, the semantics of all system calls which access the file contents are violated, because fchown(2) may cause immediate access revocation on already open files. Client side caching may lead to a delay between the time where ownership have been changed to allow access for a user and the time where the file can actually be accessed by the user on other clients.
- include <errno.h> /* for errno prototype */
- define GID 100