diff --git a/how_to b/how_to
index e9d150d..8e3e1a3 100644
--- a/how_to
+++ b/how_to
@@ -439,3 +439,10 @@ Get hardware informations:
 Music fingerprinting
     for f in *.mp3;do echo $f; python ~/src/pyacoustid/aidmatch.py $f;done > ident
     awk '/\.mp3/{f = $0;next} f{printf "mv %s \"../%s.mp3\"\n", f, $0; f=0}' ident > rename.sh
+
+Echo to stderr
+    >&2 echo "message"
+
+Reset gpg-agent passphrase cache
+    Useful mainly for testing purposes
+    echo RELOADAGENT | gpg-connect-agent