anchor.diff:                   "[var=value,...] <command,...>",
                    [{"var=value", "rebar global variables (e.g. force=1)"},
                     {"command", "Command to run (e.g. compile)"}]).
  +
  +%%
  +%% print known commands
  +%%
  +commands() ->
  +    io:format(<<
  +"analyze                              Analyze with Dialyzer~n"
  +"build_plt                            Build Dialyzer PLT~n"
  +"check_plt                            Check Dialyzer PLT~n"
  +"~n"
  +"clean                                Clean~n"
  +"compile                              Compile sources~n"
  +"~n"
  +"create      template= [var=foo,...]  Create skel based on template and vars~n"
  +"create-app                           Create simple app skel~n"
  +"create-node                          Create simple node skel~n"
  +"~n"
  +"generate    [dump_spec=0/1]          Build release with reltool~n"
  +"install     [target=]                Install build into target~n"
  +"~n"
  +"eunit       [suite=foo]              Run eunit [test/foo_tests.erl] tests~n"
  +"~n"
  +"int_test    [suite=] [case=]         Run ct suites in ./int_test~n"
  +"perf_test   [suite=] [case=]         Run ct suites in ./perf_test~n"
  +"test        [suite=] [case=]         Run ct suites in ./test~n"
  +>>).
   
   %%
   %% options accepted via getopt
  
positive.code:     rebar_config:set_global(Flag, Value).
  
  %%
  %% print help/usage string
  %%
  help() ->
  
negative.code:     %% Parse getopt options
      OptSpecList = option_spec_list(),
      case getopt:parse(OptSpecList, Args) of
          {ok, {Options, NonOptArgs}} ->
              %% Check options and maybe halt execution
              {ok, continue} = print_help_maybe_halt(Options, NonOptArgs),
  
              %% Set global variables based on getopt options
              set_global_flag(Options, verbose),
              set_global_flag(Options, force),
              DefJobs = rebar_config:get_jobs(),
              case proplists:get_value(jobs, Options, DefJobs) of
                  DefJobs ->
                      ok;
                  Jobs ->
                      rebar_config:set_global(jobs, Jobs)
              end,
  
              %% Filter all the flags (i.e. strings of form key=value) from the
              %% command line arguments. What's left will be the commands to run.
              filter_flags(NonOptArgs, []);
  
          {error, {Reason, Data}} ->
              ?ERROR("Error: ~s ~p~n~n", [Reason, Data]),
              help(),
  