make $inittab append as a for loop

zlibs/bootstrap

@@ -204,16 +204,14 @@ EOF
 
 	chroot-script -d postunpack || zerr
 
-	## below typically used in arm-sdk
-	[[ -n "$inittab" ]] && {
-		print $inittab | sudo tee -a $strapdir/etc/inittab >/dev/null
-	}
+	for i in $inittab; do
+		grep -q "^$i" $strapdir/etc/inittab && continue
+		print "$i" | sudo tee -a $strapdir/etc/inittab >/dev/null
 
 	for i in $custmodules; do
-		print $i | sudo tee -a $strapdir/etc/modules >/dev/null
+		grep -q "^$i" $strapdir/etc/modules && continue
+		print "$i" | sudo tee -a $strapdir/etc/modules >/dev/null
 	done || return 0
 
-	[[ -n "$TAR_STAGE4" ]] && {
-		bootstrap_tar_pack "$bootstrap_tgz_stage4"
-	}
+	[[ -n "$TAR_STAGE4" ]] bootstrap_tar_pack "$bootstrap_tgz_stage4"
 }