Introduce command line option to disable shell

lib/init.g

@@ -938,16 +938,6 @@ BindGlobal ("ShowSystemInformation", function ()
 end );
 
 
-#############################################################################
-##
-## Initialize the IsLIBGAP variable (if not done before). If this variable
-## is false, an interactive session will be started.
-## Otherwise no interactive session is started.
-##
-if not IsBound( IsLIBGAP ) then
-  BIND_CONSTANT( "IsLIBGAP", false );
-fi;
-
 #############################################################################
 ##
 ##  Finally, deal with the lists of global variables.
@@ -1037,8 +1027,9 @@ InstallAndCallPostRestore( function()
     od;
 end );
 
-if IsLIBGAP then
-  # GAP is used as a library, do not start an interactive session
+
+if GAPInfo.CommandLineOptions.noshell then
+  # do not start an interactive session
 elif IsHPCGAP and THREAD_UI() then
   ReadLib("hpc/consoleui.g");
   MULTI_SESSION();

lib/system.g

@@ -111,7 +111,9 @@ BIND_GLOBAL( "GAPInfo", rec(
            help := [ "Run ProfileLineByLine(<filename>) with recordMem := true on GAP start"] ),
       rec( long := "cover", default := "", arg := "<file>",
            help := [ "Run CoverageLineByLine(<filename>) on GAP start"] ),
-      rec( long := "enableMemCheck", default := false)
+      rec( long := "enableMemCheck", default := false),
+      rec( long := "noshell", default := false,
+           help := [ "Disable the GAP shell" ] )
     ],
     ) );