-DPKG_NO_TSTP - if set to a non-null value, this variable causes dpkg to run a
-child shell process instead of sending itself a SIGTSTP, when the user selects
-to background the dpkg process when it asks about conffiles.
-</para>
-</listitem>
-<listitem>
-<para>
-SHELL - used to determine which shell to run in the case when DPKG_NO_TSTP
-is set.