diff --git a/SysadminTips.page b/SysadminTips.page
index b56f17d..bdc9e2a 100644
--- a/SysadminTips.page
+++ b/SysadminTips.page
@@ -1,3 +1,10 @@
+After Debian/Ubuntu upgrade, merge local config files according to config files shipped in packages.
+
+```
+for file in $(find /etc -iname '*.dpkg-dist'); do vimdiff ${file%%.dpkg-dist} $file; done
+for file in $(find /etc -iname '*.ucf-dist'); do vimdiff ${file%%.ucf-dist} $file; done
+```
+
 Debug php with strace and php-cgi (especially useful for wp multisites).
 
 ```