Bug 445875: Make it possible to open a CPAN shell with install-module

install-module.pl

@@ -43,7 +43,7 @@ use Pod::Usage;
 our %switch;
 
 GetOptions(\%switch, 'all|a', 'upgrade-all|u', 'show-config|s', 'global|g',
-                     'help|h');
+                     'shell', 'help|h');
 
 pod2usage({ -verbose => 1 }) if $switch{'help'};
 
@@ -69,6 +69,11 @@ if (substr(CPAN->VERSION, 0, 3) < 1.8) {
     print "* You can upgrade CPAN by doing: $^X install-module.pl CPAN\n";
 }
 
+if ($switch{'shell'}) {
+    CPAN::shell();
+    exit;
+}
+
 if ($switch{'all'} || $switch{'upgrade-all'}) {
     my @modules;
     if ($switch{'upgrade-all'}) {
@@ -114,6 +119,7 @@ This script does not run on Windows.
   ./install-module.pl --all [--global]
   ./install-module.pl --upgrade-all [--global]
   ./install-module.pl --show-config
+  ./install-module.pl --shell
 
   Do "./install-module.pl --help" for more information.
 
@@ -154,6 +160,10 @@ have them installed.
 
 Prints out the CPAN configuration in raw Perl format. Useful for debugging.
 
+=item B<--shell>
+
+Starts a CPAN shell using the configuration of F<install-module.pl>.
+
 =item B<--help>
 
 Shows this help.