add short version of help, as in quit (#10055)

* MetaSema: add short version of help, as in quit
Primer: join help and ?, mention .quit and .exit
TRint: mention .?
TApplication: mention .? and CINT 2 Cling

* clarify class name with ROOT7

core/base/src/TApplication.cxx

@@ -1040,7 +1040,7 @@ void TApplication::OpenReferenceGuideFor(const TString &strippedClass)
 ////////////////////////////////////////////////////////////////////////////////
 /// The function lists useful commands (".help") or opens the online reference
 /// guide, generated with Doxygen (".help scope" or ".help scope::member").
-///
+/// \note You can use ".?" as the short version of ".help"
 /// \param[in] line command from the command line
 
 void TApplication::Help(const char *line)
@@ -1051,12 +1051,12 @@ void TApplication::Help(const char *line)
    if ((strippedCommand == ".help") || (strippedCommand == ".?")) {
       gInterpreter->ProcessLine(line);
       Printf("\nROOT special commands.");
-      Printf("==========================================================================");
+      Printf("==============================================================================");
       Printf("   .pwd                : show current directory, pad and style");
       Printf("   .ls                 : list contents of current directory");
       Printf("   .which [file]       : shows path of macro file");
-      Printf("   .help Class         : opens the reference guide for that class");
-      Printf("   .help Class::Member : opens the reference guide for function/member");
+      Printf("   .help Class         : opens the reference guide for that class (or .?)");
+      Printf("   .help Class::Member : opens the reference guide for function/member (or .?)");
       return;
    } else {
       // If the user wants to use the extended ".help scopeName" command to access
@@ -1439,7 +1439,7 @@ Longptr_t TApplication::ProcessLine(const char *line, Bool_t sync, Int_t *err)
    }
 
    if (!strcmp(line, ".reset")) {
-      // Do nothing, .reset disabled in CINT because too many side effects
+      // Do nothing, .reset disabled in Cling because too many side effects
       Printf("*** .reset not allowed, please use gROOT->Reset() ***");
       return 0;
 

core/rint/src/TRint.cxx

@@ -541,7 +541,7 @@ void TRint::PrintLogo(Bool_t lite)
       }
       lines.emplace_back(TString::Format("With %s %%s",
                                          gSystem->GetBuildCompilerVersionStr()));
-      lines.emplace_back(TString("Try '.help', '.demo', '.license', '.credits', '.quit'/'.q'%s"));
+      lines.emplace_back(TString("Try '.help'/'.?', '.demo', '.license', '.credits', '.quit'/'.q'%s"));
 
       // Find the longest line and its length:
       auto itLongest = std::max_element(lines.begin(), lines.end(),

documentation/primer/ROOT_as_calculator.md

@@ -221,9 +221,9 @@ root [1] .<command>
 
 This is a selection of the most common commands.
 
--   **quit root**, simply type `.q`
+-   **quit root**, simply type `.q` or `.quit` or `.exit`
 
--   obtain a **list of commands**, use `.?`
+-   obtain the full **list of commands**, use `.?` or `.help`
 
 -   **access the shell** of the operating system, type `.!<OS_command>`;
     try, e.g. `.!ls` or `.!pwd`
@@ -243,8 +243,6 @@ This is a selection of the most common commands.
     in order to obtain better performance or to get nearer to the
     production environment.
 
-Use `.help` at the prompt to inspect the full list.
-
 ## Plotting Measurements ##
 
 To display measurements in ROOT, including errors, there exists a
@@ -517,4 +515,5 @@ features of ROOT.
 ***Please move on to become an expert!***
 
 [^2]: All ROOT classes' names start with the letter T. A notable exception is
-RooFit. In this context all classes' names are of the form Roo*.
+RooFit. In this context all classes' names are of the form Roo*. Starting with
+ROOT7, all names start with and R.

interpreter/cling/lib/MetaProcessor/MetaSema.cpp

@@ -372,7 +372,7 @@ namespace cling {
                              "\t\t\t\t  'decl' dump ast declarations\n"
                              "\t\t\t\t  'undo' show undo stack\n"
       "\n"
-      "   " << metaString << "help\t\t\t- Shows this information\n"
+      "   " << metaString << "help\t\t\t- Shows this information (also .?)\n"
       "\n"
       "   " << metaString << "q\t\t\t\t- Exit the program\n"
       "\n";