Pre-defined

Variables

  • $!
  • The exception information message set by ‘raise’.
  • $@
  • Array of backtrace of the last exception thrown.
  • $&
  • The string matched by the last successful pattern match in this scope.
  • $`
  • The string to the left of the last successful match.
  • $'
  • The string to the right of the last successful match.
  • $+
  • The last bracket matched by the last successful match.
  • $1
  • The Nth group of the last successful match. May be > 1.
  • $~
  • The information about the last match in the current scope.
  • $=
  • The flag for case insensitive, nil by default.
  • $/
  • The input record separator, newline by default.
  • $\
  • The output record separator for the print and IO#write. Default is nil.
  • $,
  • The output field separator for the print and Array#join.
  • $;
  • The default separator for String#split.
  • $.
  • The current input line number of the last file that was read.
  • $<
  • The virtual concatenation file of the files given on command line.
  • $>
  • The default output for print, printf. $stdout by default.
  • $_
  • The last input line of string by gets or readline.
  • $0
  • Contains the name of the script being executed. May be assignable.
  • $*
  • Command line arguments given for the script sans args.
  • $$
  • The process number of the Ruby running this script.
  • $?
  • The status of the last executed child process.
  • $:
  • Load path for scripts and binary modules by load or require.
  • $"
  • The array contains the module names loaded by require.
  • $DEBUG
  • The status of the -d switch.
  • $FILENAME
  • Current input file from $<. Same as $<.filename.
  • $LOAD_PATH
  • The alias to the $:.
  • $stderr
  • The current standard error output.
  • $stdin
  • The current standard input.
  • $stdout
  • The current standard output.
  • $VERBOSE
  • The verbose flag, which is set by the -v switch.
  • $-0
  • The alias to $/
  • $-a
  • True if option -a is set. Read-only variable.
  • $-d
  • The alias to $DEBUG.
  • $-F
  • The alias to $;.
  • $-i
  • In in-place-edit mode, this variable holds the extention, otherwise nil.
  • $-I
  • The alias to $:.
  • $-l
  • True if option -l is set. Read-only variable.
  • $-p
  • True if option -p is set. Read-only variable.
  • $-v
  • The alias to $VERBOSE.

Global Constant

  • TRUE
  • The typical true value.
  • FALSE
  • The false itself.
  • NIL
  • The nil itself.
  • STDIN
  • The standard input. The default value for $stdin.
  • STDOUT
  • The standard output. The default value for $stdout.
  • STDERR
  • The standard error output. The default value for $stderr.
  • ENV
  • The hash contains current environment variables.
  • ARGF
  • The alias to the $<.
  • ARGV
  • The alias to the $*.
  • DATA
  • The file object of the script, pointing just after __END__.
  • RUBY_VERSION
  • The ruby version string (VERSION was depricated).
  • RUBY_RELEASE_DATE
  • The relase date string.
  • RUBY_PLATFORM
  • The platform identifier

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