blkspl
t->t_dcom = blkspl(pv, av);
st = blkspl(vp, st); /* Splice up the new arglst */
Char **blkspl(Char **, Char **);
STR_environ = blkspl(STR_environ, blk);
STR_environ = blkspl(STR_environ, ep + 1);
Char **av = blkspl(t->t_dcom, &pv[1]);