Invalid parameters are flagged as missing parameters, and sometimes it segmentation faults.

-ctime n requires that the file's status was last changed n*24 hours ago.
-gid n requires that the file's numeric group ID is n.

$ ./find -ctime x
./find: missing argument to `-ctime'
(This should complain about an invalid argument for -ctime.)

$ ./find -ctime x -gid x
./find: invalid argument `-gid' to `-ctime'
This should complain about an invalid argument for -ctime.

$ ./find -gid x -ctime 2
Segmentation fault
This should complain about an invalid argument for -gid.

$ ./find -gid -ctime 2
Segmentation fault
This should complain about an missing argument for -gid.



