diff -up lockdev-1.0.3/src/sample.c.cli lockdev-1.0.3/src/sample.c --- lockdev-1.0.3/src/sample.c.cli 2009-12-05 15:40:16.000000000 +0100 +++ lockdev-1.0.3/src/sample.c 2009-12-05 15:48:39.000000000 +0100 @@ -32,6 +32,8 @@ main (int argc, } else dev = p; } + if (dev == NULL) + usage(); i = 0; (void) dev_setpid(getppid()); switch( ch ) {