Merge pull request #91 from mhwombat/master

Miscellaneous minor clarifications

pills/03-enter-environment.xml

@@ -8,7 +8,7 @@
 
   <para>
     Welcome to the third Nix pill. In the <link
-    linkend="install-on-your-running-system">second pill</link> we 
+    linkend="install-on-your-running-system">second pill</link> we
     installed Nix on our running system. Now we can finally play with it a
     little, these things also apply to NixOS users.
   </para>
@@ -343,6 +343,8 @@
 
     <para>
       This is quite similar to <command>apt-get update</command>.
+      (See <link xlink:href="https://nixos.wiki/wiki/Cheatsheet">this table</link>
+      for a rough mapping between Ubuntu and NixOS package management.)
     </para>
   </section>
 
@@ -352,7 +354,7 @@
     <para>
       We learned how to query the user environment and to manipulate it by
       installing and uninstalling software. Upgrading software is also straightforward,
-      as you can read in 
+      as you can read in
       <link xlink:href="http://nixos.org/nix/manual/#idm47361539520832">the manual</link>
       (<command>nix-env -u</command> will upgrade all packages in the
       environment).

pills/03/install-hello.txt

@@ -1,4 +1,5 @@
 $ nix-env -i hello
 installing 'hello-2.10'
+[...]
 building '/nix/store/0vqw0ssmh6y5zj48yg34gc6macr883xk-user-environment.drv'...
 created 36 symlinks in user environment

pills/04-basics-of-language.xml

@@ -7,7 +7,7 @@
   <title>The Basics of the Language</title>
 
   <para>
-    Welcome to the fourth Nix pill. In the 
+    Welcome to the fourth Nix pill. In the
     <link linkend="enter-environment">previous article</link> we learned about Nix
     environments. We installed software as a user, managed their profile, switched
     between generations, and queried the Nix store. Those are the very basics of
@@ -62,6 +62,8 @@
       Launch <literal>nix repl</literal>. First of all, Nix supports basic arithmetic operations:
       <literal>+</literal>, <literal>-</literal>, and <literal>*</literal>. Integer division can be
       done with <literal>builtins.div</literal>.
+      (To exit <literal>nix repl</literal>, use the command <literal>:q</literal>.
+      Help is available through the <literal>:?</literal> command.)
     </para>
 
     <screen><xi:include href="./04/basics.txt" parse="text" /></screen>
@@ -288,7 +290,7 @@
     <screen><xi:include href="./04/let-nested.txt" parse="text" /></screen>
 
     <para>
-      With <literal>let</literal> you cannot assign twice to the same variable. However, you can 
+      With <literal>let</literal> you cannot assign twice to the same variable. However, you can
       shadow outer variables:
     </para>
 

pills/07-working-derivation.xml

@@ -65,6 +65,9 @@
 
       <programlisting><xi:include href="./07/builder.sh.txt" parse="text" /></programlisting>
 
+      The command <literal>declare -xp</literal>
+      lists exported variables.
+      (<literal>declare</literal> is a builtin bash function.)
       As we covered in the previous pill, Nix computes the output path of the
       derivation. The resulting <literal>.drv</literal> file contains a list of
       environment variables passed to the builder. One of these is