--- a/debian-apt.rst Sun May 29 19:26:03 2016 +0300
+++ b/debian-apt.rst Sun May 29 22:12:07 2016 +0300
@@ -82,8 +82,8 @@
$ netselect-apt experimental
$ netselect-apt sid
-Package priority
-================
+Check package versions and priority
+===================================
``/etc/apt/preferences``::
@@ -286,3 +286,17 @@
$ apt-rdepends -r $PKG
$ apt-rdepends -d $PKG | dot -Tsvg >$PKG.svg && see $PKG.svg
$ apt-rdepends -d -r $PKG | dot -Tsvg >$PKG.svg && see $PKG.svg
+
+Simulation mode
+===============
+
+Simulation for ``apt-get`` and ``aptitude`` shows what happen without actually
+modifying or installing any packages.
+
+Simulate install or upgrade with ``-s`` key::
+
+ $ sudo apt-get install -s xterm
+ $ sudo aptitude install -s xterm
+ $ sudo apt-get upgrade -s
+ $ sudo aptitude upgrade -s
+