## Indexes

### Index of Command-Line Options

These are the \IRB command-line options, with links to explanatory text:

- `-d`: Set `$DEBUG` and {$VERBOSE}[rdoc-ref:IRB@Verbosity]
  to `true`.
- `-E _ex_[:_in_]`: Set initial external (ex) and internal (in)
  {encodings}[rdoc-ref:IRB@Encodings] (same as `ruby -E>`).
- `-f`: Don't initialize from {configuration file}[rdoc-ref:IRB@Configuration+File].
- `-I _dirpath_`: Specify {$LOAD_PATH directory}[rdoc-ref:IRB@Load+Modules]
  (same as `ruby -I`).
- `-r _load-module_`: Require {load-module}[rdoc-ref:IRB@Load+Modules]
  (same as `ruby -r`).
- `-U`: Set external and internal {encodings}[rdoc-ref:IRB@Encodings] to UTF-8.
- `-w`: Suppress {warnings}[rdoc-ref:IRB@Warnings] (same as `ruby -w`).
- `-W[_level_]`: Set {warning level}[rdoc-ref:IRB@Warnings];
  0=silence, 1=medium, 2=verbose (same as `ruby -W`).
- `--autocomplete`: Use {auto-completion}[rdoc-ref:IRB@Automatic+Completion].
- `--back-trace-limit _n_`: Set a {backtrace limit}[rdoc-ref:IRB@Tracer];
  display at most the top `n` and bottom `n` entries.
- `--colorize`: Use {color-highlighting}[rdoc-ref:IRB@Color+Highlighting]
  for input and output.
- `--context-mode _n_`: Select method to create Binding object
  for new {workspace}[rdoc-ref:IRB@Commands]; `n` in range `0..4`.
- `--echo`: Print ({echo}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29])
  return values.
- `--extra-doc-dir _dirpath_`:
  Add a {documentation directory}[rdoc-ref:IRB@RI+Documentation+Directories]
  for the documentation dialog.
- `--inf-ruby-mode`: Set prompt mode to {:INF_RUBY}[rdoc-ref:IRB@Pre-Defined+Prompts]
  (appropriate for `inf-ruby-mode` on Emacs);
  suppresses --multiline and --singleline.
- `--inspect`: Use method `inspect` for printing ({echoing}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29])
  return values.
- `--multiline`: Use the multiline editor as the {input method}[rdoc-ref:IRB@Input+Method].
- `--noautocomplete`: Don't use {auto-completion}[rdoc-ref:IRB@Automatic+Completion].
- `--nocolorize`: Don't use {color-highlighting}[rdoc-ref:IRB@Color+Highlighting]
  for input and output.
- `--noecho`: Don't print ({echo}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29])
  return values.
- `--noecho-on-assignment`: Don't print ({echo}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29])
  result on assignment.
- `--noinspect`: Don't se method `inspect` for printing ({echoing}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29])
  return values.
- `--nomultiline`: Don't use the multiline editor as the {input method}[rdoc-ref:IRB@Input+Method].
- `--noprompt`: Don't print {prompts}[rdoc-ref:IRB@Prompt+and+Return+Formats].
- `--noscript`:  Treat the first command-line argument as a normal
  {command-line argument}[rdoc-ref:IRB@Initialization+Script],
  and include it in `ARGV`.
- `--nosingleline`: Don't use the singleline editor as the {input method}[rdoc-ref:IRB@Input+Method].
- `--noverbose`Don't print {verbose}[rdoc-ref:IRB@Verbosity] details.
- `--prompt _mode_`, `--prompt-mode _mode_`:
  Set {prompt and return formats}[rdoc-ref:IRB@Prompt+and+Return+Formats];
  `mode` may be a {pre-defined prompt}[rdoc-ref:IRB@Pre-Defined+Prompts]
  or the name of a {custom prompt}[rdoc-ref:IRB@Custom+Prompts].
- `--script`: Treat the first command-line argument as the path to an
  {initialization script}[rdoc-ref:IRB@Initialization+Script],
  and omit it from `ARGV`.
- `--simple-prompt`, `--sample-book-mode`:
  Set prompt mode to {:SIMPLE}[rdoc-ref:IRB@Pre-Defined+Prompts].
- `--singleline`: Use the singleline editor as the {input method}[rdoc-ref:IRB@Input+Method].
- `--tracer`: Use {Tracer}[rdoc-ref:IRB@Tracer] to print a stack trace for each input command.
- `--truncate-echo-on-assignment`: Print ({echo}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29])
  truncated result on assignment.
- `--verbose`Print {verbose}[rdoc-ref:IRB@Verbosity] details.
- `-v`, `--version`: Print the {IRB version}[rdoc-ref:IRB@Version].
- `-h`, `--help`: Print the {IRB help text}[rdoc-ref:IRB@Help].
- `--`: Separate options from {arguments}[rdoc-ref:IRB@Command-Line+Arguments]
  on the command-line.

### Index of \IRB.conf Entries

These are the keys for hash \IRB.conf entries, with links to explanatory text;
for each entry that is pre-defined, the initial value is given:

- `:AP_NAME`: \IRB {application name}[rdoc-ref:IRB@Application+Name];
  initial value: `'irb'`.
- `:AT_EXIT`: Array of hooks to call
  {at exit}[rdoc-ref:IRB@IRB];
  initial value: `[]`.
- `:AUTO_INDENT`: Whether {automatic indentation}[rdoc-ref:IRB@Automatic+Indentation]
  is enabled; initial value: `true`.
- `:BACK_TRACE_LIMIT`: Sets the {back trace limit}[rdoc-ref:IRB@Tracer];
  initial value: `16`.
- `:COMMAND_ALIASES`: Defines input {command aliases}[rdoc-ref:IRB@Command+Aliases];
  initial value:

        {
          "$": :show_source,
          "@": :whereami,
        }

- `:CONTEXT_MODE`: Sets the {context mode}[rdoc-ref:IRB@Context+Mode],
  the type of binding to be used when evaluating statements;
  initial value: `4`.
- `:ECHO`: Whether to print ({echo}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29])
  return values;
  initial value: `nil`, which would set `conf.echo` to `true`.
- `:ECHO_ON_ASSIGNMENT`: Whether to print ({echo}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29])
  return values on assignment;
  initial value: `nil`, which would set `conf.echo_on_assignment` to `:truncate`.
- `:EVAL_HISTORY`: How much {evaluation history}[rdoc-ref:IRB@Evaluation+History]
  is to be stored; initial value: `nil`.
- `:EXTRA_DOC_DIRS`: \Array of
  {RI documentation directories}[rdoc-ref:IRB@RI+Documentation+Directories]
  to be parsed for the documentation dialog;
  initial value: `[]`.
- `:IGNORE_EOF`: Whether to ignore {end-of-file}[rdoc-ref:IRB@End-of-File];
  initial value: `false`.
- `:IGNORE_SIGINT`: Whether to ignore {SIGINT}[rdoc-ref:IRB@SIGINT];
  initial value: `true`.
- `:INSPECT_MODE`: Whether to use method `inspect` for printing
  ({echoing}[rdoc-ref:IRB@Return-Value+Printing+-28Echoing-29]) return values;
  initial value: `true`.
- `:IRB_LIB_PATH`: The path to the {IRB library directory}[rdoc-ref:IRB@IRB+Library+Directory]; initial value:

      - `"<i>RUBY_DIR</i>/lib/ruby/gems/<i>RUBY_VER_NUM</i>/gems/irb-<i>IRB_VER_NUM</i>/lib/irb"`,

    where:

      - <i>RUBY_DIR</i> is the Ruby installation dirpath.
      - <i>RUBY_VER_NUM</i> is the Ruby version number.
      - <i>IRB_VER_NUM</i> is the \IRB version number.

- `:IRB_NAME`: {IRB name}[rdoc-ref:IRB@IRB+Name];
  initial value: `'irb'`.
- `:IRB_RC`: {Configuration monitor}[rdoc-ref:IRB@Configuration+Monitor];
  initial value: `nil`.
- `:LC_MESSAGES`: {Locale}[rdoc-ref:IRB@Locale];
  initial value: IRB::Locale object.
- `:LOAD_MODULES`: deprecated.
- `:MAIN_CONTEXT`: The {context}[rdoc-ref:IRB@Session+Context] for the main \IRB session;
  initial value: IRB::Context object.
- `:MEASURE`: Whether to
  {measure performance}[rdoc-ref:IRB@Performance+Measurement];
  initial value: `false`.
- `:MEASURE_CALLBACKS`: Callback methods for
  {performance measurement}[rdoc-ref:IRB@Performance+Measurement];
  initial value: `[]`.
- `:MEASURE_PROC`: Procs for
  {performance measurement}[rdoc-ref:IRB@Performance+Measurement];
  initial value:

        {
          :TIME=>#<Proc:0x0000556e271c6598 /var/lib/gems/3.0.0/gems/irb-1.8.3/lib/irb/init.rb:106>,
          :STACKPROF=>#<Proc:0x0000556e271c6548 /var/lib/gems/3.0.0/gems/irb-1.8.3/lib/irb/init.rb:116>
        }

- `:PROMPT`: \Hash of {defined prompts}[rdoc-ref:IRB@Prompt+and+Return+Formats];
  initial value:

        {
          :NULL=>{:PROMPT_I=>nil, :PROMPT_S=>nil, :PROMPT_C=>nil, :RETURN=>"%s\n"},
          :DEFAULT=>{:PROMPT_I=>"%N(%m):%03n> ", :PROMPT_S=>"%N(%m):%03n%l ", :PROMPT_C=>"%N(%m):%03n* ", :RETURN=>"=> %s\n"},
          :CLASSIC=>{:PROMPT_I=>"%N(%m):%03n:%i> ", :PROMPT_S=>"%N(%m):%03n:%i%l ", :PROMPT_C=>"%N(%m):%03n:%i* ", :RETURN=>"%s\n"},
          :SIMPLE=>{:PROMPT_I=>">> ", :PROMPT_S=>"%l> ", :PROMPT_C=>"?> ", :RETURN=>"=> %s\n"},
          :INF_RUBY=>{:PROMPT_I=>"%N(%m):%03n> ", :PROMPT_S=>nil, :PROMPT_C=>nil, :RETURN=>"%s\n", :AUTO_INDENT=>true},
          :XMP=>{:PROMPT_I=>nil, :PROMPT_S=>nil, :PROMPT_C=>nil, :RETURN=>"    ==>%s\n"}
        }

- `:PROMPT_MODE`: Name of {current prompt}[rdoc-ref:IRB@Prompt+and+Return+Formats];
  initial value: `:DEFAULT`.
- `:RC`: Whether a {configuration file}[rdoc-ref:IRB@Configuration+File]
  was found and interpreted;
  initial value: `true` if a configuration file was found, `false` otherwise.
- `:SAVE_HISTORY`: Number of commands to save in
  {input command history}[rdoc-ref:IRB@Input+Command+History];
  initial value: `1000`.
- `:SINGLE_IRB`: Whether command-line option `--single-irb` was given;
  initial value: `true` if the option was given, `false` otherwise.
  See {Single-IRB Mode}[rdoc-ref:IRB@Single-IRB+Mode].
- `:USE_AUTOCOMPLETE`: Whether to use
  {automatic completion}[rdoc-ref:IRB@Automatic+Completion];
  initial value: `true`.
- `:USE_COLORIZE`: Whether to use
  {color highlighting}[rdoc-ref:IRB@Color+Highlighting];
  initial value: `true`.
- `:USE_LOADER`: Whether to use the
  {IRB loader}[rdoc-ref:IRB@IRB+Loader] for `require` and `load`;
  initial value: `false`.
- `:USE_TRACER`: Whether to use the
  {IRB tracer}[rdoc-ref:IRB@Tracer];
  initial value: `false`.
- `:VERBOSE`: Whether to print {verbose output}[rdoc-ref:IRB@Verbosity];
  initial value: `nil`.
- `:__MAIN__`: The main \IRB object;
  initial value: `main`.