ash: expr -e support

commands/ash/bltin/expr.c

@@ -279,6 +279,9 @@ expr_operator(op, sp, fs)
 	    sp->u.num = expr_is_false(sp);
 	    sp->type = BOOLEAN;
 	    break;
+      case EXISTS:
+	    if (fs->rcode >= 0) goto true;
+	    goto false;
       case ISREAD:
 	    i = 04;
 	    goto permission;

commands/ash/bltin/unary_op

@@ -5,6 +5,7 @@
 # by the Ash General Public License.  See the file named LICENSE.
 
 NOT	 !	3
+EXISTS	 -e	12   OP_FILE
 ISREAD	 -r	12   OP_FILE
 ISWRITE  -w	12   OP_FILE
 ISEXEC	 -x	12   OP_FILE