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irb(1) [centos man page]

IRB(1)							 Ruby Programmers Reference Guide						    IRB(1)

irb -- Interactive Ruby Shell SYNOPSIS
irb [--version] [-dfm] [-I directory] [-r library] [--[no]inspect] [--[no]readline] [--prompt mode] [--prompt-mode mode] [--inf-ruby-mode] [--simple-prompt] [--noprompt] [--tracer] [--back-trace-limit n] [--irb_debug n] [--] [program_file] [argument ...] DESCRIPTION
irb is the REPL(read-eval-print loop) environment for Ruby programs. OPTIONS
--version Prints the version of irb. -E external[:internal] --encoding external[:internal] Same as `ruby -E' . Specifies the default value(s) for external encodings and internal encoding. Values should be separated with colon (:). You can omit the one for internal encodings, then the value (Encoding.default_internal) will be nil. -I path Same as `ruby -I' . Specifies $LOAD_PATH directory -U Same as `ruby -U' . Sets the default value for internal encodings (Encoding.default_internal) to UTF-8. -d Same as `ruby -d' . Sets $DEBUG to true. -f Suppresses read of ~/.irbrc. -h --help Prints a summary of the options. -m Bc mode (load mathn, fraction or matrix are available) -r library Same as `ruby -r'. Causes irb to load the library using require. --inspect Uses `inspect' for output (default except for bc mode) --noinspect Doesn't use inspect for output --readline Uses Readline extension module. --noreadline Doesn't use Readline extension module. --prompt mode --prompt-mode mode Switch prompt mode. Pre-defined prompt modes are `default', `simple', `xmp' and `inf-ruby'. --inf-ruby-mode Uses prompt appropriate for inf-ruby-mode on emacs. Suppresses --readline. --simple-prompt Makes prompts simple. --noprompt No prompt mode. --tracer Displays trace for each execution of commands. --back-trace-limit n Displays backtrace top n and tail n. The default value is 16. --irb_debug n Sets internal debug level to n (not for popular use) ENVIRONMENT
IRBRC Also irb depends on same variables as ruby(1). FILES
~/.irbrc Personal irb initialization. EXAMPLES
% irb irb(main):001:0> 1 + 1 2 irb(main):002:0> def t(x) irb(main):003:1> x+1 irb(main):004:1> end => nil irb(main):005:0> t(3) => 4 irb(main):006:0> if t(3) == 4 irb(main):007:1> p :ok irb(main):008:1> end :ok => :ok irb(main):009:0> quit % SEE ALSO
Security vulnerabilities should be reported via an email to <>. Reported problems will be published after being fixed. And you can report other bugs and feature requests via the Ruby Issue Tracking System ( Do not report security vulnerabilities via the system because it publishes the vulnerabilities immediately. AUTHORS
Written by Keiju ISHITSUKA. UNIX
November 7, 2012 UNIX

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JIRB1.3(1)						      General Commands Manual							JIRB1.3(1)

jirb1.3 - interactive JRuby SYNOPSIS
jirb [options] DESCRIPTION
irb stands for `interactive JRuby'. irb is a tool to execute interactively JRuby expressions read from stdin. Use of jirb is easy if you know JRuby. Executing jirb, prompts are displayed as follows. Then, enter expression of ruby. A input is executed when it is syntacticaly completed. $ jirb1.3 irb(main):001:0> 1+2 3 irb(main):002:0> class Foo irb(main):003:1> def foo irb(main):004:2> print 1 irb(main):005:2> end irb(main):006:1> end nil irb(main):007:0> And, Readline extesion module can be used with irb. Using Readline is the standard default action if Readline is installed. OPTIONS
-f suppress read ~/.irbrc -m bc mode (fraction or matrix are available) -d set $DEBUG to true (same as `ruby -d') -r load-module same as `ruby -r' --inspect uses `inspect' for output (the default except bc mode) --noinspect doesn't uses inspect for output --readline uses Readline extension module --noreadline doesn't use Readline extension module --prompt prompt-mode --prompt-mode prompt-mode switches prompt mode. Pre-defined prompt modes are `default', `simple', `xmp' and `inf-ruby' --inf-ruby-mode uses prompt appreciate for inf-ruby-mode on emacs. Suppresses --readline. --simple-prompt simple prompt mode --noprompt no prompt --tracer display trace for each execution of commands. --back-trace-limit n displayes backtrace top n and tail n. The default value is 16. --irb_debug n sets internal debug level to n (It shouldn't be used) -v, --version prints the version of irb CONFIGURATIONS
jirb reads `~/.irbrc' when it is invoked. If `~/.irbrb' doesn't exist jirb try to read in the order `.irbrc', `irb.rc', `_irbrc' then `$irbrc'. The following is altanative to the command line option. To use them type as follows in a jirb session. IRB.conf[:IRB_NAME]="irb" IRB.conf[:MATH_MODE]=false IRB.conf[:USE_TRACER]=false IRB.conf[:USE_LOADER]=false IRB.conf[:IGNORE_SIGINT]=true IRB.conf[:IGNORE_EOF]=false IRB.conf[:INSPECT_MODE]=nil IRB.conf[:IRB_RC] = nil IRB.conf[:BACK_TRACE_LIMIT]=16 IRB.conf[:USE_LOADER] = false IRB.conf[:USE_READLINE] = nil IRB.conf[:USE_TRACER] = false IRB.conf[:IGNORE_SIGINT] = true IRB.conf[:IGNORE_EOF] = false IRB.conf[:PROMPT_MODE] = :DEFALUT IRB.conf[:PROMPT] = {...} IRB.conf[:DEBUG_LEVEL]=0 IRB.conf[:VERBOSE]=true Customizing prompt To costomize the prompt you set a variable IRB.conf[:PROMPT] For example, describe as follows in `.irbrc'. IRB.conf[:PROMPT][:MY_PROMPT] = { # name of prompt mode :PROMPT_I => nil, # normal prompt :PROMPT_S => nil, # prompt for continuated strings :PROMPT_C => nil, # prompt for continuated statement :RETURN => " ==>%s " # format to return value } Then, invoke irb with the above prompt mode by $ jirb1.3 --prompt my-prompt Or add the following in `.irbrc'. IRB.conf[:PROMPT_MODE] = :MY_PROMPT Constants PROMPT_I, PROMPT_S and PROMPT_C specifies the format. In the prompt specification, some special strings are available. %N command name which is running %m to_s of main object (self) %M inspect of main object (self) %l type of string(", ', /, ]), `]' is inner %w[...] %NNi indent level. NN is degits and means as same as printf("%NNd"). It can be ommited %NNn line number. %% % For instance, the default prompt mode is defined as follows: IRB.conf[:PROMPT_MODE][:DEFAULT] = { PROMPT_I => "%N(%m):%03n:%i> ", PROMPT_S => "%N(%m):%03n:%i%l ", PROMPT_C => "%N(%m):%03n:%i* ", RETURN => "%s "} RETURN is used to printf. Configurating subirb The command line option or IRB.conf specify the default behavior of (sub)irb. On the other hand, each conf of in the next sction `6. Com- mand' is used to individually configurate (sub)irb. If proc is set to IRB.conf[:IRB_RC], its subirb will be invoked after execution of that proc under giving the context of irb as its aregument. By this mechanism each subirb can be configurated. Command For irb commands, both simple name and `irb_'-prefixed name are prepared. exit, quit, irb_exit Quits (sub)irb. if you've done cb (see below), exit from the binding mode. conf, irb_context Displays current configuration. Modifing the configuration is achieved by sending message to `conf'. conf.back_trace_limit Sets display lines of backtrace as top n and tail n. The default value is 16. conf.debug_level = N Sets debug level of irb. conf.ignore_eof = true/false Whether ^D (control-d) will be ignored or not. If false is set, ^D means quit. conf.ignore_sigint= true/false Whether ^C (control-c) will be ignored or not. If false is set, ^D means quit. If true, during input: cancel inputing then return to top level. during execute: abondon current execution. conf.inf_ruby_mode = true/false Whether inf-ruby-mode or not. The default value is false. conf.inspect_mode = true/false/nil Specifies inspect mode. true: display inspect false: display to_s nil: inspect mode in non math mode, non inspect mode in math mode. conf.irb_level The level of cb. conf.math_mode Whether bc mode or not. conf.use_loader = true/false Whether irb's own file reader method is used when load/require or not. This mode is globaly affected (irb wide). conf.prompt_c prompt for a continuating statement (e.g, immediately after of `if') conf.prompt_i standard prompt conf.prompt_s prompt for a continuating string conf.rc Whether ~/.irbrc is read or not. conf.use_prompt = true/false Prompting or not. conf.use_readline = true/false/nil Whether readline is used or not. true: uses false: doen't use nil: intends to use readline except for inf-reuby-mode (default) conf.verbose=T/F Whether verbose messages are display or not. cb, irb_change_binding [obj] Enter new binding which has a distinct scope of local variables. If obj is given, obj will be self. irb [obj] Invoke subirb. If obj is given, obj will be self. jobs, irb_jobs List of subirb fg n, irb_fg n Switch into specified subirb. The following is candidates of n: irb number thhread irb object self(obj which is specified of irb obj) kill n, irb_kill n Kill subirb. The means of n is as same as the case of irb_fg. System variable _ The latest value of evaluation (it is local) Session Example $ jirb1.3 irb(main):001:0> irb # invoke subirb irb#1(main):001:0> jobs # list of subirbs #0->irb on main (#<Thread:0x400fb7e4> : stop) #1->irb#1 on main (#<Thread:0x40125d64> : running) nil irb#1(main):002:0> fg 0 # switch job nil irb(main):002:0> class Foo;end nil irb(main):003:0> irb Foo # invoke subirb which has the # context of Foo irb#2(Foo):001:0> def foo # define Foo#foo irb#2(Foo):002:1> print 1 irb#2(Foo):003:1> end nil irb#2(Foo):004:0> fg 0 # switch job nil irb(main):004:0> jobs # list of job #0->irb on main (#<Thread:0x400fb7e4> : running) #1->irb#1 on main (#<Thread:0x40125d64> : stop) #2->irb#2 on Foo (#<Thread:0x4011d54c> : stop) nil irb(main):005:0> Foo.instance_methods # Foo#foo is defined asurely ["foo"] irb(main):006:0> fg 2 # switch job nil irb#2(Foo):005:0> def bar # define Foo#bar irb#2(Foo):006:1> print "bar" irb#2(Foo):007:1> end nil irb#2(Foo):010:0> Foo.instance_methods ["bar", "foo"] irb#2(Foo):011:0> fg 0 nil irb(main):007:0> f = #<Foo:0x4010af3c> irb(main):008:0> irb f # invoke subirb which has the # context of f (instance of Foo) irb#3(#<Foo:0x4010af3c>):001:0> jobs #0->irb on main (#<Thread:0x400fb7e4> : stop) #1->irb#1 on main (#<Thread:0x40125d64> : stop) #2->irb#2 on Foo (#<Thread:0x4011d54c> : stop) #3->irb#3 on #<Foo:0x4010af3c> (#<Thread:0x4010a1e0> : running) nil irb#3(#<Foo:0x4010af3c>):002:0> foo # evaluate 1nil irb#3(#<Foo:0x4010af3c>):003:0> bar # evaluate barnil irb#3(#<Foo:0x4010af3c>):004:0> kill 1, 2, 3# kill job nil irb(main):009:0> jobs #0->irb on main (#<Thread:0x400fb7e4> : running) nil irb(main):010:0> exit # exit Restrictions Because irb evaluates the inputs immediately after the imput is syntactically completed, irb gives slight different result than directly use ruby. Known difference is pointed out here. Declaration of the local variable The following causes an error in ruby: eval "foo = 0" foo -- -:2: undefined local variable or method `foo' for #<Object:0x40283118> (NameError) --- NameError Though, the above will successfully done by irb. >> eval "foo = 0" => 0 >> foo => 0 Ruby evaluates a code after reading entire of code and determination of the scope of local variables. On the other hand, irb do immedi- ately. More precisely, irb evaluate at first evel "foo = 0" then foo is defined on this timing. It is because of this incompatibility. If you'd like to detect those differences, begin...end can be used: >> begin ?> eval "foo = 0" >> foo >> end NameError: undefined local variable or method `foo' for #<Object:0x4013d0f0> (irb):3 (irb_local_binding):1:in `eval' Here-document Implementation of Here-document is incomplete. Symbol Irb can not always recognize a symbol as to be Symbol. Concretely, an expression have completed, however Irb regard it as continuation line. April 2007 JIRB1.3(1)
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