Embeddable" ?> This is a bit more complicated, and requires some knowledge of C, but it's very powerful - trust me!

Let's create a Tcl command: 

int Getpw_Init(Tcl_Interp *interp)
{
    Tcl_CreateObjCommand(interp,
			 "getpw",
			 GetPW,
			 NULL,
			 (Tcl_CmdDeleteProc *)NULL);
    return TCL_OK;
}