Perl Variables

$_	default input and pattern-searching space
$a/$b	special package variables when using sort()
$	contains the subpattern from the corresponding set of capturing parentheses from the last pattern match
$&	string matched by the last successful pattern match
$'	string preceding whatever was matched by the last successful pattern match
$'	the string following whatever was matched by the last successful pattern match
$+	text matched by the last bracket of the last successful search pattern
$^N	text matched by the used group most-recently closed of the last successful search pattern
@+	arrays holds the offsets of the ends of the last successful submatches in the currently active dynamic scope
$*	set to a non-zero integer value to do multi-line matching within a string, 0 to tell Perl that it can assume that strings contain a single line, for pattern matches.
$.	current line number for the last filehandle accessed
$/	input record separator, newline by default.
$\|	if set to nonzero, forces a flush right away and after every write or print to the currently selected output channel
$,	output field separator for the print operator
$\	output record separator for the print operator
$"	like $, except that it applies to array and slice values interpolated into a double-quoted string
$;	subscript separator for multidimensional array emulation
$#	output format for printed numbers
$%	current page number of the currently selected output channel
$=	current page length (in printable lines) of the currently selected output channel
$-	number of lines left on the page of the currently selected output channel
@-	$-[n] is the offset of the start of the substring matched by the n-th subpattern. $-[0] is the offset of the start of the last succesful match
$~	name of the current report format for the currently selected output channel
$^	name of the current top-of-page format for the currently selected output channel
$^L	what formats output as a form feed
$^A	current value of the write() accumulator for format() lines
$?	status returned by the last pipe close, backtick command, successful call to wait() or waitpid(), or from the system() operator.
$^[ENCODING]	object reference to the Encode object that is used to convert the source code to Unicode
$!	1. numerically: yields the current value of the C errno variable 2. string: yields the corresponding system error string
%!	each element of %! has a true value only if $! is set to that value
$^E	error information specific to the current OS
$@	Perl syntax error message from the last eval() operator
$$	process number of the Perl running this script
$<	real uid of this process
$>	effective uid of this process
$(	real gid of this process
$)	effective gid of this process
$0	name of the program being executed
$[	index of the first element in an array, and of the first character in a substring
$]	version + patchlevel/1000 of the Perl interpreter
$^C	current value of the flag associated with the -c switch
$^D	current value of the debugging (-D) flags
$^F	maximum system file descriptor, ordinarily 2
$^H	compile-time hints for the Perl interpreter (internal use only)
%^H	same scoping semantic as $^H
$^\|	current value of the inplace-edit extension
$^M	contents are a possible emergency memory pool Perl can use after die()ing
$^O	name of the OS under which this copy of Perl was built, as determined during the configuration process
${^OPEN}	inter variable used by PerlIO...
$^P	internal variable (bits) for debugging support
$^R	rresult of evaluation of the last successful (?{code}) regular expression assertion
$^S	current state of the interpreter
$^T	time at which the program began running, in seconds since the epoch
${^TAINT}	reflects if taint mode is on or off
$^V	revision, version, and subversion of the Perl interpreter
$^W	current value of the warning switch
${^WARNING_BITS}	current set of warning checks enabled by the use warnings pragma
${^WIDE_SYSTEM_CALLS}	global flag that enables system call made by Perl to use wide character API's native to the system, if available (Windows only!)
$^X	filename used to execute the curreny copy of Perl, from C's argv[0].
ARGV	special filehandle that iterates over command-line filenames in @ARGV
$ARGV	contains the name of the current file when reading from <>
@ARGV	contains the command-line arguments intended for the script
ARGVOUT	special filehandle that points to the currently open output file when doing edit-in-place processing with -i
@F	contains the fields of each line read in when autosplit mode is turned on
@INC	contains the list of places that the do EXPR, require, or use constructs look for their library files
@_	within a subroutine, contains the parameters passed
%INC	contains entries for each filename included via the do, require, or use operators (key: filename/value: location of the file found)
%ENV	current environment
%SIG	signal handlers for signals
$@/$!/$^E/$?	information about different types of error conditions encountered during execution of a Perl program