Quick reference to some features of the Ruby programming language.

Reference

Code Description
$! latest error message
$@ location of error
$_ string last read by gets
$. line number last read by interpreter
$& string last matched by regexp
$~ the last regexp match, as an array of subexpressions
$n the nth subexpression in the last match (same as $~[n])
$= case-insensitivity flag
$/ input record separator
$\ output record separator
$0 the name of the ruby script file
$* (or ARGV) the command line arguments
$$ interpreter’s process ID
$? exit status of last executed child process
$-i $-l $-p $-v Command line switches
$-v (or $VERBOSE) verbose mode
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