Predefined Variables list : Predefined Variables « Language Basics « Ruby






Predefined Variables list


variable   Description
$!         last exception raised. Access with => in a rescue clause.
$@         Stack backtrace of the last exception, retrievable via Exception#backtrace.
$&         String matched by the last successful pattern match, 
           or nil if the last pattern match failed. 
           Read only. 
           Local.
$'         String preceding what was matched by the last successful pattern match, 
           or nil if the last pattern match failed. 
           Same as m.pre_match where m is a MatchData object. 
           Read only. 
           Local.
$'         String following what was matched by the last successful pattern match, 
           or nil if the last pattern match failed. 
           Same as m.post_match where m is a MatchData object. 
           Read only. 
           Local.
$+         Last bracket matched by the last successful search pattern, 
           or nil if the last pattern match failed. 
           Read only. 
           Local.
$1, $2...  Subpattern from the corresponding set of parentheses in the last successful pattern matched, 
           or nil if the last pattern match failed. 
           Same as m[n] where m is a MatchData object. 
           Read only. 
           Local.
$~         Information about the last match in the current scope. 
           Regex#match returns the last match information. 
           Setting this variable affects match variables like $&, $+, $1, $2, etc. 
           The nth subexpression can be retrieved by $~[nth]. Local.
$=         Case-insensitive flag; 
           nil by default.
$/         Input record separator; 
           newline by default. 
           If it is set to nil, a whole file will be read at once. 
           gets, readline, etc., take the input record separator as an optional argument.
$\         Output record separator for print and IO#write; 
           nil by default.
$,         Output field separator between arguments; 
           the default separator for Array#join.
$;         Default separator for String#split; 
           nil by default.
$.         Input line number of the last file that was read. 
           Same as ARGF.lineno.
$<         Virtual concatenation file of the files given by command-line arguments
           $<.filename returns the current filename. 
           Synonym for ARGF.
$>         Default output for print, printf, and $stdout by default. 
           Synonym for $defout.
$_         Last input line of string by gets or readline in the current scope; 
           set to nil if gets or readline meets EOF. 
           Local.
$0         Name of the current Ruby program being executed.
$*         Command-line arguments given for the script. 
           The options for the Ruby interpreter are already removed.
$$         Process number (process.pid) of the Ruby program being executed.
$?         Exit status of the last executed process.
$:         Synonym for $LOAD_PATH.
$"         Array containing the module names loaded by require. 
           Used to prevent require from loading modules twice.
$DEBUG     True if -d or --debug switch is set.
$defout    Default output for print, printf, and $stdout by default. 
           Synonym for $>.
$F         Receives output from split when -a is specified. 
           Set if -a is set along with -p and -n.
$FILENAME  Name of the file currently being read from ARGF. Same as ARGF.filename or $<.filename.
$LOAD_PATH Synonym for $:.
$SAFE      Security level:
           0   No checks on externally supplied tainted data are allowed.
           1   tainted data are forbidden.
           2   files are forbidden.
           3   All newly created objects are considered tainted.
           4   Modification of global data is forbidden.

$stdin     standard input; 
           STDIN by default.
$stdout    standard output; STDOUT by default.
$stderr    standard error output; STDERR by default.
$VERBOSE   True if verbose flag is set by the -v, -w, or --verbose switch of the Ruby interpreter.
$-0        Alias of $/.
$-a        True if option -a is set. Read only.
$-d        Alias of $DEBUG.
$-F        Alias of $;.
$-i        In in-place-edit mode, holds the extension; 
           otherwise nil. 
           Can enable or disable in-place-edit mode.
$-I        Alias of $:.
$-l        True if option -lis is set. Read only.
$-p        True if option -pis is set. Read only.

 








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