change the user ID and group ID of a file
#include <sys/types.h> #include <unistd.h> int chown( const char *path, uid_t owner, gid_t group );
The chown() function changes the user ID and group ID of the file specified by path to be the numeric values contained in owner and group, respectively.
Only processes with an effective user ID equal to the user ID of the file or with appropriate privileges (for example, the super user) may change the ownership of a file.
In QNX4.1 or later, the _POSIX_CHOWN_RESTRICTED flag is enforced. This means that only the super user may change the ownership of a file. The group of a file may be changed by the super user, or also by a process with the effective user ID equal to the user ID of the file, if (and only if) owner is equal to the user ID of the file and group is equal to the effective group ID of the calling process.
If the path argument refers to a regular file, the set-user-ID (S_ISUID) and set-group-ID (S_ISGID) bits of the file mode are cleared, if the function is successful.
If chown() succeeds, the st_ctime field of the file is marked for update.
/* * change the ownership of a list of files * to the current user/group */ #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <unistd.h> int main( int argc, char **argv ) { int i; int ecode = 0; for( i = 1; i < argc; i++ ) { if( chown( argv[i], getuid(), getgid() ) == -1 ) { perror( argv[i] ); ecode++; } } return( ecode ); }
POSIX 1003.1
Safety: | |
---|---|
Interrupt handler | No |
Signal handler | Yes, but modifies errno |
Thread | Yes |
chmod(), errno, fstat(), open(), stat()