int main( int argc, char **argv )
{
        char *prog_name = basename( *argv );
        print_prompt( prog_name );
        read_command();
        for ( ;; ) {
                int pid = fork();
                if ( pid == 0 ) {
                        execvp( args[ 0 ], args );
                }
                wait( NULL );
                print_prompt( prog_name );
                read_command();
        }
}