From 534798dbd2c55c16f1c662bd60b30dba013a8943 Mon Sep 17 00:00:00 2001
From: Johannes 'josch' Schauer <josch@mister-muffin.de>
Date: Sun, 15 Nov 2020 11:27:51 +0100
Subject: [PATCH] add example for how to use a cache directory

---
 mmdebstrap | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/mmdebstrap b/mmdebstrap
index 446d173..87a4098 100755
--- a/mmdebstrap
+++ b/mmdebstrap
@@ -6448,6 +6448,17 @@ Build a non-Debian chroot like Ubuntu bionic:
     $ mmdebstrap --aptopt='Dir::Etc::Trusted
        "/usr/share/keyrings/ubuntu-keyring-2012-archive.gpg"' bionic bionic.tar
 
+If, for some reason, you cannot use a caching proxy like apt-cacher or
+apt-cacher-ng, you can use the B<sync-in> and B<sync-out> special hooks to
+synchronize a directory outside the chroot with F</var/cache/apt/archives>
+inside the chroot.
+
+    $ mmdebstrap --variant=apt --skip=download/empty --skip=essential/unlink \
+        --setup-hook='mkdir -p ./cache "$1"/var/cache/apt/archives/' \
+        --setup-hook='sync-in ./cache /var/cache/apt/archives/' \
+        --customize-hook='sync-out /var/cache/apt/archives ./cache' \
+        unstable /dev/null
+
 =head1 ENVIRONMENT VARIABLES
 
 =over 8