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PERLVAR(1)	       Perl Programmers	Reference Guide		    PERLVAR(1)

NAME
       perlvar - Perl predefined variables

DESCRIPTION
   The Syntax of Variable Names
       Variable	names in Perl can have several formats.	 Usually, they must
       begin with a letter or underscore, in which case	they can be
       arbitrarily long	(up to an internal limit of 251	characters) and	may
       contain letters,	digits,	underscores, or	the special sequence "::" or
       "'".  In	this case, the part before the last "::" or "'"	is taken to be
       a package qualifier; see	perlmod.  A Unicode letter that	is not ASCII
       is not considered to be a letter	unless "use utf8" is in	effect,	and
       somewhat	more complicated rules apply; see "Identifier parsing" in
       perldata	for details.

       Perl variable names may also be a sequence of digits, a single
       punctuation character, or the two-character sequence: "^" (caret	or
       CIRCUMFLEX ACCENT) followed by any one of the characters	"[][A-Z^_?\]".
       These names are all reserved for	special	uses by	Perl; for example, the
       all-digits names	are used to hold data captured by backreferences after
       a regular expression match.

       Since Perl v5.6.0, Perl variable	names may also be alphanumeric strings
       preceded	by a caret.  These must	all be written in the form "${^Foo}";
       the braces are not optional.  "${^Foo}" denotes the scalar variable
       whose name is considered	to be a	control-"F" followed by	two "o"'s.
       These variables are reserved for	future special uses by Perl, except
       for the ones that begin with "^_" (caret-underscore).  No name that
       begins with "^_"	will acquire a special meaning in any future version
       of Perl;	such names may therefore be used safely	in programs.  $^_
       itself, however,	is reserved.

       Perl identifiers	that begin with	digits or punctuation characters are
       exempt from the effects of the "package"	declaration and	are always
       forced to be in package "main"; they are	also exempt from "strict
       'vars'" errors.	A few other names are also exempt in these ways:

	   ENV	    STDIN
	   INC	    STDOUT
	   ARGV	    STDERR
	   ARGVOUT
	   SIG

       In particular, the special "${^_XYZ}" variables are always taken	to be
       in package "main", regardless of	any "package" declarations presently
       in scope.

SPECIAL	VARIABLES
       The following names have	special	meaning	to Perl.  Most punctuation
       names have reasonable mnemonics,	or analogs in the shells.
       Nevertheless, if	you wish to use	long variable names, you need only
       say:

	   use English;

       at the top of your program.  This aliases all the short names to	the
       long names in the current package.  Some	even have medium names,
       generally borrowed from awk.  For more info, please see English.

       Before you continue, note the sort order	for variables.	In general, we
       first list the variables	in case-insensitive, almost-lexigraphical
       order (ignoring the "{" or "^" preceding	words, as in "${^UNICODE}" or
       $^T), although $_ and @_	move up	to the top of the pile.	 For variables
       with the	same identifier, we list it in order of	scalar,	array, hash,
       and bareword.

   General Variables
       $ARG
       $_      The default input and pattern-searching space.  The following
	       pairs are equivalent:

		   while (<>) {...}    # equivalent only in while!
		   while (defined($_ = <>)) {...}

		   /^Subject:/
		   $_ =~ /^Subject:/

		   tr/a-z/A-Z/
		   $_ =~ tr/a-z/A-Z/

		   chomp
		   chomp($_)

	       Here are	the places where Perl will assume $_ even if you don't
	       use it:

	       o  The following	functions use $_ as a default argument:

		  abs, alarm, chomp, chop, chr,	chroot,	cos, defined, eval,
		  evalbytes, exp, fc, glob, hex, int, lc, lcfirst, length,
		  log, lstat, mkdir, oct, ord, pos, print, printf, quotemeta,
		  readlink, readpipe, ref, require, reverse (in	scalar context
		  only), rmdir,	say, sin, split	(for its second	argument),
		  sqrt,	stat, study, uc, ucfirst, unlink, unpack.

	       o  All file tests ("-f",	"-d") except for "-t", which defaults
		  to STDIN.  See "-X" in perlfunc

	       o  The pattern matching operations "m//", "s///"	and "tr///"
		  (aka "y///") when used without an "=~" operator.

	       o  The default iterator variable	in a "foreach" loop if no
		  other	variable is supplied.

	       o  The implicit iterator	variable in the	"grep()" and "map()"
		  functions.

	       o  The implicit variable	of "given()".

	       o  The default place to put the next value or input record when
		  a "<FH>", "readline",	"readdir" or "each" operation's	result
		  is tested by itself as the sole criterion of a "while" test.
		  Outside a "while" test, this will not	happen.

	       $_ is a global variable.

	       However,	between	perl v5.10.0 and v5.24.0, it could be used
	       lexically by writing "my	$_".  Making $_	refer to the global $_
	       in the same scope was then possible with	"our $_".  This
	       experimental feature was	removed	and is now a fatal error, but
	       you may encounter it in older code.

	       Mnemonic: underline is understood in certain operations.

       @ARG
       @_      Within a	subroutine the array @_	contains the parameters	passed
	       to that subroutine.  Inside a subroutine, @_ is the default
	       array for the array operators "pop" and "shift".

	       See perlsub.

       $LIST_SEPARATOR
       $"      When an array or	an array slice is interpolated into a double-
	       quoted string or	a similar context such as "/.../", its
	       elements	are separated by this value.  Default is a space.  For
	       example,	this:

		   print "The array is:	@array\n";

	       is equivalent to	this:

		   print "The array is:	" . join($", @array) . "\n";

	       Mnemonic: works in double-quoted	context.

       $PROCESS_ID
       $PID
       $$      The process number of the Perl running this script.  Though you
	       can set this variable, doing so is generally discouraged,
	       although	it can be invaluable for some testing purposes.	 It
	       will be reset automatically across "fork()" calls.

	       Note for	Linux and Debian GNU/kFreeBSD users: Before Perl
	       v5.16.0 perl would emulate POSIX	semantics on Linux systems
	       using LinuxThreads, a partial implementation of POSIX Threads
	       that has	since been superseded by the Native POSIX Thread
	       Library (NPTL).

	       LinuxThreads is now obsolete on Linux, and caching "getpid()"
	       like this made embedding	perl unnecessarily complex (since
	       you'd have to manually update the value of $$), so now $$ and
	       "getppid()" will	always return the same values as the
	       underlying C library.

	       Debian GNU/kFreeBSD systems also	used LinuxThreads up until and
	       including the 6.0 release, but after that moved to FreeBSD
	       thread semantics, which are POSIX-like.

	       To see if your system is	affected by this discrepancy check if
	       "getconf	GNU_LIBPTHREAD_VERSION | grep -q NPTL" returns a false
	       value.  NTPL threads preserve the POSIX semantics.

	       Mnemonic: same as shells.

       $PROGRAM_NAME
       $0      Contains	the name of the	program	being executed.

	       On some (but not	all) operating systems assigning to $0
	       modifies	the argument area that the "ps"	program	sees.  On some
	       platforms you may have to use special "ps" options or a
	       different "ps" to see the changes.  Modifying the $0 is more
	       useful as a way of indicating the current program state than it
	       is for hiding the program you're	running.

	       Note that there are platform-specific limitations on the
	       maximum length of $0.  In the most extreme case it may be
	       limited to the space occupied by	the original $0.

	       In some platforms there may be arbitrary	amount of padding, for
	       example space characters, after the modified name as shown by
	       "ps".  In some platforms	this padding may extend	all the	way to
	       the original length of the argument area, no matter what	you do
	       (this is	the case for example with Linux	2.2).

	       Note for	BSD users: setting $0 does not completely remove
	       "perl" from the ps(1) output.  For example, setting $0 to
	       "foobar"	may result in "perl: foobar (perl)" (whether both the
	       "perl: "	prefix and the " (perl)" suffix	are shown depends on
	       your exact BSD variant and version).  This is an	operating
	       system feature, Perl cannot help	it.

	       In multithreaded	scripts	Perl coordinates the threads so	that
	       any thread may modify its copy of the $0	and the	change becomes
	       visible to ps(1)	(assuming the operating	system plays along).
	       Note that the view of $0	the other threads have will not	change
	       since they have their own copies	of it.

	       If the program has been given to	perl via the switches "-e" or
	       "-E", $0	will contain the string	"-e".

	       On Linux	as of perl v5.14.0 the legacy process name will	be set
	       with prctl(2), in addition to altering the POSIX	name via
	       "argv[0]" as perl has done since	version	4.000.	Now system
	       utilities that read the legacy process name such	as ps, top and
	       killall will recognize the name you set when assigning to $0.
	       The string you supply will be cut off at	16 bytes, this is a
	       limitation imposed by Linux.

	       Mnemonic: same as sh and	ksh.

       $REAL_GROUP_ID
       $GID
       $(      The real	gid of this process.  If you are on a machine that
	       supports	membership in multiple groups simultaneously, gives a
	       space separated list of groups you are in.  The first number is
	       the one returned	by "getgid()", and the subsequent ones by
	       "getgroups()", one of which may be the same as the first
	       number.

	       However,	a value	assigned to $( must be a single	number used to
	       set the real gid.  So the value given by	$( should not be
	       assigned	back to	$( without being forced	numeric, such as by
	       adding zero.  Note that this is different to the	effective gid
	       ($)) which does take a list.

	       You can change both the real gid	and the	effective gid at the
	       same time by using "POSIX::setgid()".  Changes to $( require a
	       check to	$!  to detect any possible errors after	an attempted
	       change.

	       Mnemonic: parentheses are used to group things.	The real gid
	       is the group you	left, if you're	running	setgid.

       $EFFECTIVE_GROUP_ID
       $EGID
       $)      The effective gid of this process.  If you are on a machine
	       that supports membership	in multiple groups simultaneously,
	       gives a space separated list of groups you are in.  The first
	       number is the one returned by "getegid()", and the subsequent
	       ones by "getgroups()", one of which may be the same as the
	       first number.

	       Similarly, a value assigned to $) must also be a	space-
	       separated list of numbers.  The first number sets the effective
	       gid, and	the rest (if any) are passed to	"setgroups()".	To get
	       the effect of an	empty list for "setgroups()", just repeat the
	       new effective gid; that is, to force an effective gid of	5 and
	       an effectively empty "setgroups()" list,	say " $) = "5 5" ".

	       You can change both the effective gid and the real gid at the
	       same time by using "POSIX::setgid()" (use only a	single numeric
	       argument).  Changes to $) require a check to $! to detect any
	       possible	errors after an	attempted change.

	       $<, $>, $( and $) can be	set only on machines that support the
	       corresponding set[re][ug]id() routine.  $( and $) can be
	       swapped only on machines	supporting "setregid()".

	       Mnemonic: parentheses are used to group things.	The effective
	       gid is the group	that's right for you, if you're	running
	       setgid.

       $REAL_USER_ID
       $UID
       $<      The real	uid of this process.  You can change both the real uid
	       and the effective uid at	the same time by using
	       "POSIX::setuid()".  Since changes to $< require a system	call,
	       check $!	after a	change attempt to detect any possible errors.

	       Mnemonic: it's the uid you came from, if	you're running setuid.

       $EFFECTIVE_USER_ID
       $EUID
       $>      The effective uid of this process.  For example:

		   $< =	$>;	       # set real to effective uid
		   ($<,$>) = ($>,$<);  # swap real and effective uids

	       You can change both the effective uid and the real uid at the
	       same time by using "POSIX::setuid()".  Changes to $> require a
	       check to	$! to detect any possible errors after an attempted
	       change.

	       $< and $> can be	swapped	only on	machines supporting
	       "setreuid()".

	       Mnemonic: it's the uid you went to, if you're running setuid.

       $SUBSCRIPT_SEPARATOR
       $SUBSEP
       $;      The subscript separator for multidimensional array emulation.
	       If you refer to a hash element as

		   $foo{$x,$y,$z}

	       it really means

		   $foo{join($;, $x, $y, $z)}

	       But don't put

		   @foo{$x,$y,$z}      # a slice--note the @

	       which means

		   ($foo{$x},$foo{$y},$foo{$z})

	       Default is "\034", the same as SUBSEP in	awk.  If your keys
	       contain binary data there might not be any safe value for $;.

	       Consider	using "real" multidimensional arrays as	described in
	       perllol.

	       Mnemonic: comma (the syntactic subscript	separator) is a	semi-
	       semicolon.

       $a
       $b      Special package variables when using "sort()", see "sort" in
	       perlfunc.  Because of this specialness $a and $b	don't need to
	       be declared (using "use vars", or "our()") even when using the
	       "strict 'vars'" pragma.	Don't lexicalize them with "my $a" or
	       "my $b" if you want to be able to use them in the "sort()"
	       comparison block	or function.

       %ENV    The hash	%ENV contains your current environment.	 Setting a
	       value in	"ENV" changes the environment for any child processes
	       you subsequently	"fork()" off.

	       As of v5.18.0, both keys	and values stored in %ENV are
	       stringified.

		   my $foo = 1;
		   $ENV{'bar'} = \$foo;
		   if( ref $ENV{'bar'} ) {
		       say "Pre	5.18.0 Behaviour";
		   } else {
		       say "Post 5.18.0	Behaviour";
		   }

	       Previously, only	child processes	received stringified values:

		   my $foo = 1;
		   $ENV{'bar'} = \$foo;

		   # Always printed 'non ref'
		   system($^X, '-e',
			  q/print ( ref	$ENV{'bar'}  ? 'ref' : 'non ref' ) /);

	       This happens because you	can't really share arbitrary data
	       structures with foreign processes.

       $OLD_PERL_VERSION
       $]      The revision, version, and subversion of	the Perl interpreter,
	       represented as a	decimal	of the form 5.XXXYYY, where XXX	is the
	       version / 1e3 and YYY is	the subversion / 1e6.  For example,
	       Perl v5.10.1 would be "5.010001".

	       This variable can be used to determine whether the Perl
	       interpreter executing a script is in the	right range of
	       versions:

		   warn	"No PerlIO!\n" if "$]" < 5.008;

	       When comparing $], numeric comparison operators should be used,
	       but the variable	should be stringified first to avoid issues
	       where its original numeric value	is inaccurate.

	       See also	the documentation of "use VERSION" and "require
	       VERSION"	for a convenient way to	fail if	the running Perl
	       interpreter is too old.

	       See "$^V" for a representation of the Perl version as a version
	       object, which allows more flexible string comparisons.

	       The main	advantage of $]	over $^V is that it works the same on
	       any version of Perl.  The disadvantages are that	it can't
	       easily be compared to versions in other formats (e.g. literal
	       v-strings, "v1.2.3" or version objects) and numeric comparisons
	       are subject to the binary floating point	representation;	it's
	       good for	numeric	literal	version	checks and bad for comparing
	       to a variable that hasn't been sanity-checked.

	       The $OLD_PERL_VERSION form was added in Perl v5.20.0 for
	       historical reasons but its use is discouraged. (If your reason
	       to use $] is to run code	on old perls then referring to it as
	       $OLD_PERL_VERSION would be self-defeating.)

	       Mnemonic: Is this version of perl in the	right bracket?

       $SYSTEM_FD_MAX
       $^F     The maximum system file descriptor, ordinarily 2.  System file
	       descriptors are passed to "exec()"ed processes, while higher
	       file descriptors	are not.  Also,	during an "open()", system
	       file descriptors	are preserved even if the "open()" fails
	       (ordinary file descriptors are closed before the	"open()" is
	       attempted).  The	close-on-exec status of	a file descriptor will
	       be decided according to the value of $^F	when the corresponding
	       file, pipe, or socket was opened, not the time of the "exec()".

       @F      The array @F contains the fields	of each	line read in when
	       autosplit mode is turned	on.  See perlrun for the -a switch.
	       This array is package-specific, and must	be declared or given a
	       full package name if not	in package main	when running under
	       "strict 'vars'".

       @INC    The array @INC contains the list	of places that the "do EXPR",
	       "require", or "use" constructs look for their library files.
	       It initially consists of	the arguments to any -I	command-line
	       switches, followed by the default Perl library, probably
	       /usr/local/lib/perl.  Prior to Perl 5.26, "." -which represents
	       the current directory, was included in @INC; it has been
	       removed.	This change in behavior	is documented in
	       "PERL_USE_UNSAFE_INC" and it is not recommended that "."	be re-
	       added to	@INC.  If you need to modify @INC at runtime, you
	       should use the "use lib"	pragma to get the machine-dependent
	       library properly	loaded as well:

		   use lib '/mypath/libdir/';
		   use SomeMod;

	       You can also insert hooks into the file inclusion system	by
	       putting Perl code directly into @INC.  Those hooks may be
	       subroutine references, array references or blessed objects.
	       See "require" in	perlfunc for details.

       %INC    The hash	%INC contains entries for each filename	included via
	       the "do", "require", or "use" operators.	 The key is the
	       filename	you specified (with module names converted to
	       pathnames), and the value is the	location of the	file found.
	       The "require" operator uses this	hash to	determine whether a
	       particular file has already been	included.

	       If the file was loaded via a hook (e.g. a subroutine reference,
	       see "require" in	perlfunc for a description of these hooks),
	       this hook is by default inserted	into %INC in place of a
	       filename.  Note,	however, that the hook may have	set the	%INC
	       entry by	itself to provide some more specific info.

       $INPLACE_EDIT
       $^I     The current value of the	inplace-edit extension.	 Use "undef"
	       to disable inplace editing.

	       Mnemonic: value of -i switch.

       @ISA    Each package contains a special array called @ISA which
	       contains	a list of that class's parent classes, if any. This
	       array is	simply a list of scalars, each of which	is a string
	       that corresponds	to a package name. The array is	examined when
	       Perl does method	resolution, which is covered in	perlobj.

	       To load packages	while adding them to @ISA, see the parent
	       pragma. The discouraged base pragma does	this as	well, but
	       should not be used except when compatibility with the
	       discouraged fields pragma is required.

       $^M     By default, running out of memory is an untrappable, fatal
	       error.  However,	if suitably built, Perl	can use	the contents
	       of $^M as an emergency memory pool after	"die()"ing.  Suppose
	       that your Perl were compiled with "-DPERL_EMERGENCY_SBRK" and
	       used Perl's malloc.  Then

		   $^M = 'a' x (1 << 16);

	       would allocate a	64K buffer for use in an emergency.  See the
	       INSTALL file in the Perl	distribution for information on	how to
	       add custom C compilation	flags when compiling perl.  To
	       discourage casual use of	this advanced feature, there is	no
	       English long name for this variable.

	       This variable was added in Perl 5.004.

       $OSNAME
       $^O     The name	of the operating system	under which this copy of Perl
	       was built, as determined	during the configuration process.  For
	       examples	see "PLATFORMS"	in perlport.

	       The value is identical to $Config{'osname'}.  See also Config
	       and the -V command-line switch documented in perlrun.

	       In Windows platforms, $^O is not	very helpful: since it is
	       always "MSWin32", it doesn't tell the difference	between
	       95/98/ME/NT/2000/XP/CE/.NET.  Use "Win32::GetOSName()" or
	       Win32::GetOSVersion() (see Win32	and perlport) to distinguish
	       between the variants.

	       This variable was added in Perl 5.003.

       %SIG    The hash	%SIG contains signal handlers for signals.  For
	       example:

		   sub handler {   # 1st argument is signal name
		       my($sig)	= @_;
		       print "Caught a SIG$sig--shutting down\n";
		       close(LOG);
		       exit(0);
		       }

		   $SIG{'INT'}	= \&handler;
		   $SIG{'QUIT'}	= \&handler;
		   ...
		   $SIG{'INT'}	= 'DEFAULT';   # restore default action
		   $SIG{'QUIT'}	= 'IGNORE';    # ignore	SIGQUIT

	       Using a value of	'IGNORE' usually has the effect	of ignoring
	       the signal, except for the "CHLD" signal.  See perlipc for more
	       about this special case.	 Using an empty	string or "undef" as
	       the value has the same effect as	'DEFAULT'.

	       Here are	some other examples:

		   $SIG{"PIPE"}	= "Plumber";   # assumes main::Plumber (not
					       # recommended)
		   $SIG{"PIPE"}	= \&Plumber;   # just fine; assume current
					       # Plumber
		   $SIG{"PIPE"}	= *Plumber;    # somewhat esoteric
		   $SIG{"PIPE"}	= Plumber();   # oops, what did	Plumber()
					       # return??

	       Be sure not to use a bareword as	the name of a signal handler,
	       lest you	inadvertently call it.

	       Using a string that doesn't correspond to any existing function
	       or a glob that doesn't contain a	code slot is equivalent	to
	       'IGNORE', but a warning is emitted when the handler is being
	       called (the warning is not emitted for the internal hooks
	       described below).

	       If your system has the "sigaction()" function then signal
	       handlers	are installed using it.	 This means you	get reliable
	       signal handling.

	       The default delivery policy of signals changed in Perl v5.8.0
	       from immediate (also known as "unsafe") to deferred, also known
	       as "safe	signals".  See perlipc for more	information.

	       Certain internal	hooks can be also set using the	%SIG hash.
	       The routine indicated by	$SIG{__WARN__} is called when a
	       warning message is about	to be printed.	The warning message is
	       passed as the first argument.  The presence of a	"__WARN__"
	       hook causes the ordinary	printing of warnings to	"STDERR" to be
	       suppressed.  You	can use	this to	save warnings in a variable,
	       or turn warnings	into fatal errors, like	this:

		   local $SIG{__WARN__}	= sub {	die $_[0] };
		   eval	$proggie;

	       As the 'IGNORE' hook is not supported by	"__WARN__", its	effect
	       is the same as using 'DEFAULT'.	You can	disable	warnings using
	       the empty subroutine:

		   local $SIG{__WARN__}	= sub {};

	       The routine indicated by	$SIG{__DIE__} is called	when a fatal
	       exception is about to be	thrown.	 The error message is passed
	       as the first argument.  When a "__DIE__"	hook routine returns,
	       the exception processing	continues as it	would have in the
	       absence of the hook, unless the hook routine itself exits via a
	       "goto &sub", a loop exit, or a "die()".	The "__DIE__" handler
	       is explicitly disabled during the call, so that you can die
	       from a "__DIE__"	handler.  Similarly for	"__WARN__".

	       The $SIG{__DIE__} hook is called	even inside an "eval()". It
	       was never intended to happen this way, but an implementation
	       glitch made this	possible. This used to be deprecated, as it
	       allowed strange action at a distance like rewriting a pending
	       exception in $@.	Plans to rectify this have been	scrapped, as
	       users found that	rewriting a pending exception is actually a
	       useful feature, and not a bug.

	       The $SIG{__DIE__} doesn't support 'IGNORE'; it has the same
	       effect as 'DEFAULT'.

	       "__DIE__"/"__WARN__" handlers are very special in one respect:
	       they may	be called to report (probable) errors found by the
	       parser.	In such	a case the parser may be in inconsistent
	       state, so any attempt to	evaluate Perl code from	such a handler
	       will probably result in a segfault.  This means that warnings
	       or errors that result from parsing Perl should be used with
	       extreme caution,	like this:

		   require Carp	if defined $^S;
		   Carp::confess("Something wrong") if defined &Carp::confess;
		   die "Something wrong, but could not load Carp to give "
		     . "backtrace...\n\t"
		     . "To see backtrace try starting Perl with	-MCarp switch";

	       Here the	first line will	load "Carp" unless it is the parser
	       who called the handler.	The second line	will print backtrace
	       and die if "Carp" was available.	 The third line	will be
	       executed	only if	"Carp" was not available.

	       Having to even think about the $^S variable in your exception
	       handlers	is simply wrong.  $SIG{__DIE__}	as currently
	       implemented invites grievous and	difficult to track down
	       errors.	Avoid it and use an "END{}" or CORE::GLOBAL::die
	       override	instead.

	       See "die" in perlfunc, "warn" in	perlfunc, "eval" in perlfunc,
	       and warnings for	additional information.

       $BASETIME
       $^T     The time	at which the program began running, in seconds since
	       the epoch (beginning of 1970).  The values returned by the -M,
	       -A, and -C filetests are	based on this value.

       $PERL_VERSION
       $^V     The revision, version, and subversion of	the Perl interpreter,
	       represented as a	version	object.

	       This variable first appeared in perl v5.6.0; earlier versions
	       of perl will see	an undefined value.  Before perl v5.10.0 $^V
	       was represented as a v-string rather than a version object.

	       $^V can be used to determine whether the	Perl interpreter
	       executing a script is in	the right range	of versions.  For
	       example:

		   warn	"Hashes	not randomized!\n" if !$^V or $^V lt v5.8.1

	       While version objects overload stringification, to portably
	       convert $^V into	its string representation, use "sprintf()"'s
	       "%vd" conversion, which works for both v-strings	or version
	       objects:

		   printf "version is v%vd\n", $^V;  # Perl's version

	       See the documentation of	"use VERSION" and "require VERSION"
	       for a convenient	way to fail if the running Perl	interpreter is
	       too old.

	       See also	"$]" for a decimal representation of the Perl version.

	       The main	advantage of $^V over $] is that, for Perl v5.10.0 or
	       later, it overloads operators, allowing easy comparison against
	       other version representations (e.g. decimal, literal v-string,
	       "v1.2.3", or objects).  The disadvantage	is that	prior to
	       v5.10.0,	it was only a literal v-string,	which can't be easily
	       printed or compared, whereas the	behavior of $] is unchanged on
	       all versions of Perl.

	       Mnemonic: use ^V	for a version object.

       ${^WIN32_SLOPPY_STAT}
	       If this variable	is set to a true value,	then "stat()" on
	       Windows will not	try to open the	file.  This means that the
	       link count cannot be determined and file	attributes may be out
	       of date if additional hardlinks to the file exist.  On the
	       other hand, not opening the file	is considerably	faster,
	       especially for files on network drives.

	       This variable could be set in the sitecustomize.pl file to
	       configure the local Perl	installation to	use "sloppy" "stat()"
	       by default.  See	the documentation for -f in perlrun for	more
	       information about site customization.

	       This variable was added in Perl v5.10.0.

       $EXECUTABLE_NAME
       $^X     The name	used to	execute	the current copy of Perl, from C's
	       "argv[0]" or (where supported) /proc/self/exe.

	       Depending on the	host operating system, the value of $^X	may be
	       a relative or absolute pathname of the perl program file, or
	       may be the string used to invoke	perl but not the pathname of
	       the perl	program	file.  Also, most operating systems permit
	       invoking	programs that are not in the PATH environment
	       variable, so there is no	guarantee that the value of $^X	is in
	       PATH.  For VMS, the value may or	may not	include	a version
	       number.

	       You usually can use the value of	$^X to re-invoke an
	       independent copy	of the same perl that is currently running,
	       e.g.,

		   @first_run =	`$^X -le "print	int rand 100 for 1..100"`;

	       But recall that not all operating systems support forking or
	       capturing of the	output of commands, so this complex statement
	       may not be portable.

	       It is not safe to use the value of $^X as a path	name of	a
	       file, as	some operating systems that have a mandatory suffix on
	       executable files	do not require use of the suffix when invoking
	       a command.  To convert the value	of $^X to a path name, use the
	       following statements:

		   # Build up a	set of file names (not command names).
		   use Config;
		   my $this_perl = $^X;
		   if ($^O ne 'VMS') {
		       $this_perl .= $Config{_exe}
			 unless	$this_perl =~ m/$Config{_exe}$/i;
		       }

	       Because many operating systems permit anyone with read access
	       to the Perl program file	to make	a copy of it, patch the	copy,
	       and then	execute	the copy, the security-conscious Perl
	       programmer should take care to invoke the installed copy	of
	       perl, not the copy referenced by	$^X.  The following statements
	       accomplish this goal, and produce a pathname that can be
	       invoked as a command or referenced as a file.

		   use Config;
		   my $secure_perl_path	= $Config{perlpath};
		   if ($^O ne 'VMS') {
		       $secure_perl_path .= $Config{_exe}
			   unless $secure_perl_path =~ m/$Config{_exe}$/i;
		       }

   Variables related to	regular	expressions
       Most of the special variables related to	regular	expressions are	side
       effects.	 Perl sets these variables when	it has a successful match, so
       you should check	the match result before	using them.  For instance:

	   if( /P(A)TT(ER)N/ ) {
	       print "I	found $1 and $2\n";
	       }

       These variables are read-only and dynamically-scoped, unless we note
       otherwise.

       The dynamic nature of the regular expression variables means that their
       value is	limited	to the block that they are in, as demonstrated by this
       bit of code:

	   my $outer = 'Wallace	and Grommit';
	   my $inner = 'Mutt and Jeff';

	   my $pattern = qr/(\S+) and (\S+)/;

	   sub show_n {	print "\$1 is $1; \$2 is $2\n" }

	   {
	   OUTER:
	       show_n()	if $outer =~ m/$pattern/;

	       INNER: {
		   show_n() if $inner =~ m/$pattern/;
		   }

	       show_n();
	   }

       The output shows	that while in the "OUTER" block, the values of $1 and
       $2 are from the match against $outer.  Inside the "INNER" block,	the
       values of $1 and	$2 are from the	match against $inner, but only until
       the end of the block (i.e. the dynamic scope).  After the "INNER" block
       completes, the values of	$1 and $2 return to the	values for the match
       against $outer even though we have not made another match:

	   $1 is Wallace; $2 is	Grommit
	   $1 is Mutt; $2 is Jeff
	   $1 is Wallace; $2 is	Grommit

       Performance issues

       Traditionally in	Perl, any use of any of	the three variables  "$`", $&
       or "$'" (or their "use English" equivalents) anywhere in	the code,
       caused all subsequent successful	pattern	matches	to make	a copy of the
       matched string, in case the code	might subsequently access one of those
       variables.  This	imposed	a considerable performance penalty across the
       whole program, so generally the use of these variables has been
       discouraged.

       In Perl 5.6.0 the "@-" and "@+" dynamic arrays were introduced that
       supply the indices of successful	matches. So you	could for example do
       this:

	   $str	=~ /pattern/;

	   print $`, $&, $'; # bad: performance	hit

	   print	     # good: no	performance hit
	       substr($str, 0,	   $-[0]),
	       substr($str, $-[0], $+[0]-$-[0]),
	       substr($str, $+[0]);

       In Perl 5.10.0 the "/p" match operator flag and the "${^PREMATCH}",
       "${^MATCH}", and	"${^POSTMATCH}"	variables were introduced, that
       allowed you to suffer the penalties only	on patterns marked with	"/p".

       In Perl 5.18.0 onwards, perl started noting the presence	of each	of the
       three variables separately, and only copied that	part of	the string
       required; so in

	   $`; $&; "abcdefgh" =~ /d/

       perl would only copy the	"abcd" part of the string. That	could make a
       big difference in something like

	   $str	= 'x' x	1_000_000;
	   $&; # whoops
	   $str	=~ /x/g	# one char copied a million times, not a million chars

       In Perl 5.20.0 a	new copy-on-write system was enabled by	default, which
       finally fixes all performance issues with these three variables,	and
       makes them safe to use anywhere.

       The "Devel::NYTProf" and	"Devel::FindAmpersand" modules can help	you
       find uses of these problematic match variables in your code.

       $<digits> ($1, $2, ...)
	       Contains	the subpattern from the	corresponding set of capturing
	       parentheses from	the last successful pattern match, not
	       counting	patterns matched in nested blocks that have been
	       exited already.

	       Note there is a distinction between a capture buffer which
	       matches the empty string	a capture buffer which is optional.
	       Eg, "(x?)" and "(x)?" The latter	may be undef, the former not.

	       These variables are read-only and dynamically-scoped.

	       Mnemonic: like \digits.

       @{^CAPTURE}
	       An array	which exposes the contents of the capture buffers, if
	       any, of the last	successful pattern match, not counting
	       patterns	matched	in nested blocks that have been	exited
	       already.

	       Note that the 0 index of	@{^CAPTURE} is equivalent to $1, the 1
	       index is	equivalent to $2, etc.

		   if ("foal"=~/(.)(.)(.)(.)/) {
		       print join "-", @{^CAPTURE};
		   }

	       should output "f-o-a-l".

	       See also	"$<digits> ($1,	$2, ...)", "%{^CAPTURE}" and
	       "%{^CAPTURE_ALL}".

	       Note that unlike	most other regex magic variables there is no
	       single letter equivalent	to "@{^CAPTURE}".

	       This variable was added in 5.25.7

       $MATCH
       $&      The string matched by the last successful pattern match (not
	       counting	any matches hidden within a BLOCK or "eval()" enclosed
	       by the current BLOCK).

	       See "Performance	issues"	above for the serious performance
	       implications of using this variable (even once) in your code.

	       This variable is	read-only and dynamically-scoped.

	       Mnemonic: like "&" in some editors.

       ${^MATCH}
	       This is similar to $& ($MATCH) except that it does not incur
	       the performance penalty associated with that variable.

	       See "Performance	issues"	above.

	       In Perl v5.18 and earlier, it is	only guaranteed	to return a
	       defined value when the pattern was compiled or executed with
	       the "/p"	modifier.  In Perl v5.20, the "/p" modifier does
	       nothing,	so "${^MATCH}" does the	same thing as $MATCH.

	       This variable was added in Perl v5.10.0.

	       This variable is	read-only and dynamically-scoped.

       $PREMATCH
       $`      The string preceding whatever was matched by the	last
	       successful pattern match, not counting any matches hidden
	       within a	BLOCK or "eval"	enclosed by the	current	BLOCK.

	       See "Performance	issues"	above for the serious performance
	       implications of using this variable (even once) in your code.

	       This variable is	read-only and dynamically-scoped.

	       Mnemonic: "`" often precedes a quoted string.

       ${^PREMATCH}
	       This is similar to "$`" ($PREMATCH) except that it does not
	       incur the performance penalty associated	with that variable.

	       See "Performance	issues"	above.

	       In Perl v5.18 and earlier, it is	only guaranteed	to return a
	       defined value when the pattern was compiled or executed with
	       the "/p"	modifier.  In Perl v5.20, the "/p" modifier does
	       nothing,	so "${^PREMATCH}" does the same	thing as $PREMATCH.

	       This variable was added in Perl v5.10.0.

	       This variable is	read-only and dynamically-scoped.

       $POSTMATCH
       $'      The string following whatever was matched by the	last
	       successful pattern match	(not counting any matches hidden
	       within a	BLOCK or "eval()" enclosed by the current BLOCK).
	       Example:

		   local $_ = 'abcdefghi';
		   /def/;
		   print "$`:$&:$'\n";	       # prints	abc:def:ghi

	       See "Performance	issues"	above for the serious performance
	       implications of using this variable (even once) in your code.

	       This variable is	read-only and dynamically-scoped.

	       Mnemonic: "'" often follows a quoted string.

       ${^POSTMATCH}
	       This is similar to "$'" ($POSTMATCH) except that	it does	not
	       incur the performance penalty associated	with that variable.

	       See "Performance	issues"	above.

	       In Perl v5.18 and earlier, it is	only guaranteed	to return a
	       defined value when the pattern was compiled or executed with
	       the "/p"	modifier.  In Perl v5.20, the "/p" modifier does
	       nothing,	so "${^POSTMATCH}" does	the same thing as $POSTMATCH.

	       This variable was added in Perl v5.10.0.

	       This variable is	read-only and dynamically-scoped.

       $LAST_PAREN_MATCH
       $+      The text	matched	by the highest used capture group of the last
	       successful search pattern.  It is logically equivalent to the
	       highest numbered	capture	variable ($1, $2, ...) which has a
	       defined value.

	       This is useful if you don't know	which one of a set of
	       alternative patterns matched.  For example:

		   /Version: (.*)|Revision: (.*)/ && ($rev = $+);

	       This variable is	read-only and dynamically-scoped.

	       Mnemonic: be positive and forward looking.

       $LAST_SUBMATCH_RESULT
       $^N     The text	matched	by the used group most-recently	closed (i.e.
	       the group with the rightmost closing parenthesis) of the	last
	       successful search pattern. This is subtly different from	$+.
	       For example in

		   "ab"	=~ /^((.)(.))$/

	       we have

		   $1,$^N   have the value "ab"
		   $2	    has	 the value "a"
		   $3,$+    have the value "b"

	       This is primarily used inside "(?{...})"	blocks for examining
	       text recently matched.  For example, to effectively capture
	       text to a variable (in addition to $1, $2, etc.), replace
	       "(...)" with

		   (?:(...)(?{ $var = $^N }))

	       By setting and then using $var in this way relieves you from
	       having to worry about exactly which numbered set	of parentheses
	       they are.

	       This variable was added in Perl v5.8.0.

	       Mnemonic: the (possibly)	Nested parenthesis that	most recently
	       closed.

       @LAST_MATCH_END
       @+      This array holds	the offsets of the ends	of the last successful
	       submatches in the currently active dynamic scope.  $+[0]	is the
	       offset into the string of the end of the	entire match.  This is
	       the same	value as what the "pos"	function returns when called
	       on the variable that was	matched	against.  The nth element of
	       this array holds	the offset of the nth submatch,	so $+[1] is
	       the offset past where $1	ends, $+[2] the	offset past where $2
	       ends, and so on.	 You can use $#+ to determine how many
	       subgroups were in the last successful match.  See the examples
	       given for the "@-" variable.

	       This variable was added in Perl v5.6.0.

       %{^CAPTURE}
       %LAST_PAREN_MATCH
       %+      Similar to "@+",	the "%+" hash allows access to the named
	       capture buffers,	should they exist, in the last successful
	       match in	the currently active dynamic scope.

	       For example, $+{foo} is equivalent to $1	after the following
	       match:

		   'foo' =~ /(?<foo>foo)/;

	       The keys	of the "%+" hash list only the names of	buffers	that
	       have captured (and that are thus	associated to defined values).

	       If multiple distinct capture groups have	the same name, then
	       $+{NAME}	will refer to the leftmost defined group in the	match.

	       The underlying behaviour	of "%+"	is provided by the
	       Tie::Hash::NamedCapture module.

	       Note: "%-" and "%+" are tied views into a common	internal hash
	       associated with the last	successful regular expression.
	       Therefore mixing	iterative access to them via "each" may	have
	       unpredictable results.  Likewise, if the	last successful	match
	       changes,	then the results may be	surprising.

	       This variable was added in Perl v5.10.0.	The "%{^CAPTURE}"
	       alias was added in 5.25.7.

	       This variable is	read-only and dynamically-scoped.

       @LAST_MATCH_START
       @-      "$-[0]" is the offset of	the start of the last successful
	       match.  "$-[n]" is the offset of	the start of the substring
	       matched by n-th subpattern, or undef if the subpattern did not
	       match.

	       Thus, after a match against $_, $& coincides with "substr $_,
	       $-[0], $+[0] - $-[0]".  Similarly, $n coincides with "substr
	       $_, $-[n], $+[n]	- $-[n]" if "$-[n]" is defined,	and $+
	       coincides with "substr $_, $-[$#-], $+[$#-] - $-[$#-]".	One
	       can use "$#-" to	find the last matched subgroup in the last
	       successful match.  Contrast with	$#+, the number	of subgroups
	       in the regular expression.  Compare with	"@+".

	       This array holds	the offsets of the beginnings of the last
	       successful submatches in	the currently active dynamic scope.
	       "$-[0]" is the offset into the string of	the beginning of the
	       entire match.  The nth element of this array holds the offset
	       of the nth submatch, so "$-[1]" is the offset where $1 begins,
	       "$-[2]" the offset where	$2 begins, and so on.

	       After a match against some variable $var:

	       "$`" is the same	as "substr($var, 0, $-[0])"
	       $& is the same as "substr($var, $-[0], $+[0] - $-[0])"
	       "$'" is the same	as "substr($var, $+[0])"
	       $1 is the same as "substr($var, $-[1], $+[1] - $-[1])"
	       $2 is the same as "substr($var, $-[2], $+[2] - $-[2])"
	       $3 is the same as "substr($var, $-[3], $+[3] - $-[3])"

	       This variable was added in Perl v5.6.0.

       %{^CAPTURE_ALL}
       %-      Similar to "%+",	this variable allows access to the named
	       capture groups in the last successful match in the currently
	       active dynamic scope.  To each capture group name found in the
	       regular expression, it associates a reference to	an array
	       containing the list of values captured by all buffers with that
	       name (should there be several of	them), in the order where they
	       appear.

	       Here's an example:

		   if ('1234' =~ /(?<A>1)(?<B>2)(?<A>3)(?<B>4)/) {
		       foreach my $bufname (sort keys %-) {
			   my $ary = $-{$bufname};
			   foreach my $idx (0..$#$ary) {
			       print "\$-{$bufname}[$idx] : ",
				     (defined($ary->[$idx])
					 ? "'$ary->[$idx]'"
					 : "undef"),
				     "\n";
			   }
		       }
		   }

	       would print out:

		   $-{A}[0] : '1'
		   $-{A}[1] : '3'
		   $-{B}[0] : '2'
		   $-{B}[1] : '4'

	       The keys	of the "%-" hash correspond to all buffer names	found
	       in the regular expression.

	       The behaviour of	"%-" is	implemented via	the
	       Tie::Hash::NamedCapture module.

	       Note: "%-" and "%+" are tied views into a common	internal hash
	       associated with the last	successful regular expression.
	       Therefore mixing	iterative access to them via "each" may	have
	       unpredictable results.  Likewise, if the	last successful	match
	       changes,	then the results may be	surprising.

	       This variable was added in Perl v5.10.0.	The "%{^CAPTURE_ALL}"
	       alias was added in 5.25.7.

	       This variable is	read-only and dynamically-scoped.

       $LAST_REGEXP_CODE_RESULT
       $^R     The result of evaluation	of the last successful "(?{ code })"
	       regular expression assertion (see perlre).  May be written to.

	       This variable was added in Perl 5.005.

       ${^RE_COMPILE_RECURSION_LIMIT}
	       The current value giving	the maximum number of open but
	       unclosed	parenthetical groups there may be at any point during
	       a regular expression compilation.  The default is currently
	       1000 nested groups.  You	may adjust it depending	on your	needs
	       and the amount of memory	available.

	       This variable was added in Perl v5.30.0.

       ${^RE_DEBUG_FLAGS}
	       The current value of the	regex debugging	flags.	Set to 0 for
	       no debug	output even when the "re 'debug'" module is loaded.
	       See re for details.

	       This variable was added in Perl v5.10.0.

       ${^RE_TRIE_MAXBUF}
	       Controls	how certain regex optimisations	are applied and	how
	       much memory they	utilize.  This value by	default	is 65536 which
	       corresponds to a	512kB temporary	cache.	Set this to a higher
	       value to	trade memory for speed when matching large
	       alternations.  Set it to	a lower	value if you want the
	       optimisations to	be as conservative of memory as	possible but
	       still occur, and	set it to a negative value to prevent the
	       optimisation and	conserve the most memory.  Under normal
	       situations this variable	should be of no	interest to you.

	       This variable was added in Perl v5.10.0.

   Variables related to	filehandles
       Variables that depend on	the currently selected filehandle may be set
       by calling an appropriate object	method on the "IO::Handle" object,
       although	this is	less efficient than using the regular built-in
       variables.  (Summary lines below	for this contain the word HANDLE.)
       First you must say

	   use IO::Handle;

       after which you may use either

	   method HANDLE EXPR

       or more safely,

	   HANDLE->method(EXPR)

       Each method returns the old value of the	"IO::Handle" attribute.	 The
       methods each take an optional EXPR, which, if supplied, specifies the
       new value for the "IO::Handle" attribute	in question.  If not supplied,
       most methods do nothing to the current value--except for	"autoflush()",
       which will assume a 1 for you, just to be different.

       Because loading in the "IO::Handle" class is an expensive operation,
       you should learn	how to use the regular built-in	variables.

       A few of	these variables	are considered "read-only".  This means	that
       if you try to assign to this variable, either directly or indirectly
       through a reference, you'll raise a run-time exception.

       You should be very careful when modifying the default values of most
       special variables described in this document.  In most cases you	want
       to localize these variables before changing them, since if you don't,
       the change may affect other modules which rely on the default values of
       the special variables that you have changed.  This is one of the
       correct ways to read the	whole file at once:

	   open	my $fh,	"<", "foo" or die $!;
	   local $/; # enable localized	slurp mode
	   my $content = <$fh>;
	   close $fh;

       But the following code is quite bad:

	   open	my $fh,	"<", "foo" or die $!;
	   undef $/; # enable slurp mode
	   my $content = <$fh>;
	   close $fh;

       since some other	module,	may want to read data from some	file in	the
       default "line mode", so if the code we have just	presented has been
       executed, the global value of $/	is now changed for any other code
       running inside the same Perl interpreter.

       Usually when a variable is localized you	want to	make sure that this
       change affects the shortest scope possible.  So unless you are already
       inside some short "{}" block, you should	create one yourself.  For
       example:

	   my $content = '';
	   open	my $fh,	"<", "foo" or die $!;
	   {
	       local $/;
	       $content	= <$fh>;
	   }
	   close $fh;

       Here is an example of how your own code can go broken:

	   for ( 1..3 ){
	       $\ = "\r\n";
	       nasty_break();
	       print "$_";
	   }

	   sub nasty_break {
	       $\ = "\f";
	       # do something with $_
	   }

       You probably expect this	code to	print the equivalent of

	   "1\r\n2\r\n3\r\n"

       but instead you get:

	   "1\f2\f3\f"

       Why? Because "nasty_break()" modifies "$\" without localizing it	first.
       The value you set in  "nasty_break()" is	still there when you return.
       The fix is to add "local()" so the value	doesn't	leak out of
       "nasty_break()":

	   local $\ = "\f";

       It's easy to notice the problem in such a short example,	but in more
       complicated code	you are	looking	for trouble if you don't localize
       changes to the special variables.

       $ARGV   Contains	the name of the	current	file when reading from "<>".

       @ARGV   The array @ARGV contains	the command-line arguments intended
	       for the script.	$#ARGV is generally the	number of arguments
	       minus one, because $ARGV[0] is the first	argument, not the
	       program's command name itself.  See "$0"	for the	command	name.

       ARGV    The special filehandle that iterates over command-line
	       filenames in @ARGV.  Usually written as the null	filehandle in
	       the angle operator "<>".	 Note that currently "ARGV" only has
	       its magical effect within the "<>" operator; elsewhere it is
	       just a plain filehandle corresponding to	the last file opened
	       by "<>".	 In particular,	passing	"\*ARGV" as a parameter	to a
	       function	that expects a filehandle may not cause	your function
	       to automatically	read the contents of all the files in @ARGV.

       ARGVOUT The special filehandle that points to the currently open	output
	       file when doing edit-in-place processing	with -i.  Useful when
	       you have	to do a	lot of inserting and don't want	to keep
	       modifying $_.  See perlrun for the -i switch.

       IO::Handle->output_field_separator( EXPR	)
       $OUTPUT_FIELD_SEPARATOR
       $OFS
       $,      The output field	separator for the print	operator.  If defined,
	       this value is printed between each of print's arguments.
	       Default is "undef".

	       You cannot call "output_field_separator()" on a handle, only as
	       a static	method.	 See IO::Handle.

	       Mnemonic: what is printed when there is a "," in	your print
	       statement.

       HANDLE->input_line_number( EXPR )
       $INPUT_LINE_NUMBER
       $NR
       $.      Current line number for the last	filehandle accessed.

	       Each filehandle in Perl counts the number of lines that have
	       been read from it.  (Depending on the value of $/, Perl's idea
	       of what constitutes a line may not match	yours.)	 When a	line
	       is read from a filehandle (via "readline()" or "<>"), or	when
	       "tell()"	or "seek()" is called on it, $.	becomes	an alias to
	       the line	counter	for that filehandle.

	       You can adjust the counter by assigning to $., but this will
	       not actually move the seek pointer.  Localizing $. will not
	       localize	the filehandle's line count.  Instead, it will
	       localize	perl's notion of which filehandle $. is	currently
	       aliased to.

	       $. is reset when	the filehandle is closed, but not when an open
	       filehandle is reopened without an intervening "close()".	 For
	       more details, see "I/O Operators" in perlop.  Because "<>"
	       never does an explicit close, line numbers increase across
	       "ARGV" files (but see examples in "eof" in perlfunc).

	       You can also use	"HANDLE->input_line_number(EXPR)" to access
	       the line	counter	for a given filehandle without having to worry
	       about which handle you last accessed.

	       Mnemonic: many programs use "." to mean the current line
	       number.

       IO::Handle->input_record_separator( EXPR	)
       $INPUT_RECORD_SEPARATOR
       $RS
       $/      The input record	separator, newline by default.	This
	       influences Perl's idea of what a	"line" is.  Works like awk's
	       RS variable, including treating empty lines as a	terminator if
	       set to the null string (an empty	line cannot contain any	spaces
	       or tabs).  You may set it to a multi-character string to	match
	       a multi-character terminator, or	to "undef" to read through the
	       end of file.  Setting it	to "\n\n" means	something slightly
	       different than setting to "", if	the file contains consecutive
	       empty lines.  Setting to	"" will	treat two or more consecutive
	       empty lines as a	single empty line.  Setting to "\n\n" will
	       blindly assume that the next input character belongs to the
	       next paragraph, even if it's a newline.

		   local $/;	       # enable	"slurp"	mode
		   local $_ = <FH>;    # whole file now	here
		   s/\n[ \t]+/ /g;

	       Remember: the value of $/ is a string, not a regex.  awk	has to
	       be better for something.	:-)

	       Setting $/ to an	empty string --	the so-called paragraph	mode
	       -- merits special attention.  When $/ is	set to "" and the
	       entire file is read in with that	setting, any sequence of
	       consecutive newlines "\n\n" at the beginning of the file	is
	       discarded.  With	the exception of the final record in the file,
	       each sequence of	characters ending in two or more newlines is
	       treated as one record and is read in to end in exactly two
	       newlines.  If the last record in	the file ends in zero or one
	       consecutive newlines, that record is read in with that number
	       of newlines.  If	the last record	ends in	two or more
	       consecutive newlines, it	is read	in with	two newlines like all
	       preceding records.

	       Suppose we wrote	the following string to	a file:

		   my $string =	"\n\n\n";
		   $string .= "alpha beta\ngamma delta\n\n\n";
		   $string .= "epsilon zeta eta\n\n";
		   $string .= "theta\n";

		   my $file = 'simple_file.txt';
		   open	my $OUT, '>', $file or die;
		   print $OUT $string;
		   close $OUT or die;

	       Now we read that	file in	paragraph mode:

		   local $/ = ""; # paragraph mode
		   open	my $IN,	'<', $file or die;
		   my @records = <$IN>;
		   close $IN or	die;

	       @records	will consist of	these 3	strings:

		   (
		     "alpha beta\ngamma	delta\n\n",
		     "epsilon zeta eta\n\n",
		     "theta\n",
		   )

	       Setting $/ to a reference to an integer,	scalar containing an
	       integer,	or scalar that's convertible to	an integer will
	       attempt to read records instead of lines, with the maximum
	       record size being the referenced	integer	number of characters.
	       So this:

		   local $/ = \32768; #	or \"32768", or	\$var_containing_32768
		   open	my $fh,	"<", $myfile or	die $!;
		   local $_ = <$fh>;

	       will read a record of no	more than 32768	characters from	$fh.
	       If you're not reading from a record-oriented file (or your OS
	       doesn't have record-oriented files), then you'll	likely get a
	       full chunk of data with every read.  If a record	is larger than
	       the record size you've set, you'll get the record back in
	       pieces.	Trying to set the record size to zero or less is
	       deprecated and will cause $/ to have the	value of "undef",
	       which will cause	reading	in the (rest of	the) whole file.

	       As of 5.19.9 setting $/ to any other form of reference will
	       throw a fatal exception.	This is	in preparation for supporting
	       new ways	to set $/ in the future.

	       On VMS only, record reads bypass	PerlIO layers and any
	       associated buffering, so	you must not mix record	and non-record
	       reads on	the same filehandle.  Record mode mixes	with line mode
	       only when the same buffering layer is in	use for	both modes.

	       You cannot call "input_record_separator()" on a handle, only as
	       a static	method.	 See IO::Handle.

	       See also	"Newlines" in perlport.	 Also see "$.".

	       Mnemonic: / delimits line boundaries when quoting poetry.

       IO::Handle->output_record_separator( EXPR )
       $OUTPUT_RECORD_SEPARATOR
       $ORS
       $\      The output record separator for the print operator.  If
	       defined,	this value is printed after the	last of	print's
	       arguments.  Default is "undef".

	       You cannot call "output_record_separator()" on a	handle,	only
	       as a static method.  See	IO::Handle.

	       Mnemonic: you set "$\" instead of adding	"\n" at	the end	of the
	       print.  Also, it's just like $/,	but it's what you get "back"
	       from Perl.

       HANDLE->autoflush( EXPR )
       $OUTPUT_AUTOFLUSH
       $|      If set to nonzero, forces a flush right away and	after every
	       write or	print on the currently selected	output channel.
	       Default is 0 (regardless	of whether the channel is really
	       buffered	by the system or not; $| tells you only	whether	you've
	       asked Perl explicitly to	flush after each write).  STDOUT will
	       typically be line buffered if output is to the terminal and
	       block buffered otherwise.  Setting this variable	is useful
	       primarily when you are outputting to a pipe or socket, such as
	       when you	are running a Perl program under rsh and want to see
	       the output as it's happening.  This has no effect on input
	       buffering.  See "getc" in perlfunc for that.  See "select" in
	       perlfunc	on how to select the output channel.  See also
	       IO::Handle.

	       Mnemonic: when you want your pipes to be	piping hot.

       ${^LAST_FH}
	       This read-only variable contains	a reference to the last-read
	       filehandle.  This is set	by "<HANDLE>", "readline", "tell",
	       "eof" and "seek".  This is the same handle that $. and "tell"
	       and "eof" without arguments use.	 It is also the	handle used
	       when Perl appends ", <STDIN> line 1" to an error	or warning
	       message.

	       This variable was added in Perl v5.18.0.

       Variables related to formats

       The special variables for formats are a subset of those for
       filehandles.  See perlform for more information about Perl's formats.

       $ACCUMULATOR
       $^A     The current value of the	"write()" accumulator for "format()"
	       lines.  A format	contains "formline()" calls that put their
	       result into $^A.	 After calling its format, "write()" prints
	       out the contents	of $^A and empties.  So	you never really see
	       the contents of $^A unless you call "formline()"	yourself and
	       then look at it.	 See perlform and "formline PICTURE,LIST" in
	       perlfunc.

       IO::Handle->format_formfeed(EXPR)
       $FORMAT_FORMFEED
       $^L     What formats output as a	form feed.  The	default	is "\f".

	       You cannot call "format_formfeed()" on a	handle,	only as	a
	       static method.  See IO::Handle.

       HANDLE->format_page_number(EXPR)
       $FORMAT_PAGE_NUMBER
       $%      The current page	number of the currently	selected output
	       channel.

	       Mnemonic: "%" is	page number in nroff.

       HANDLE->format_lines_left(EXPR)
       $FORMAT_LINES_LEFT
       $-      The number of lines left	on the page of the currently selected
	       output channel.

	       Mnemonic: lines_on_page - lines_printed.

       IO::Handle->format_line_break_characters	EXPR
       $FORMAT_LINE_BREAK_CHARACTERS
       $:      The current set of characters after which a string may be
	       broken to fill continuation fields (starting with "^") in a
	       format.	The default is " \n-", to break	on a space, newline,
	       or a hyphen.

	       You cannot call "format_line_break_characters()"	on a handle,
	       only as a static	method.	 See IO::Handle.

	       Mnemonic: a "colon" in poetry is	a part of a line.

       HANDLE->format_lines_per_page(EXPR)
       $FORMAT_LINES_PER_PAGE
       $=      The current page	length (printable lines) of the	currently
	       selected	output channel.	 The default is	60.

	       Mnemonic: = has horizontal lines.

       HANDLE->format_top_name(EXPR)
       $FORMAT_TOP_NAME
       $^      The name	of the current top-of-page format for the currently
	       selected	output channel.	 The default is	the name of the
	       filehandle with "_TOP" appended.	 For example, the default
	       format top name for the "STDOUT"	filehandle is "STDOUT_TOP".

	       Mnemonic: points	to top of page.

       HANDLE->format_name(EXPR)
       $FORMAT_NAME
       $~      The name	of the current report format for the currently
	       selected	output channel.	 The default format name is the	same
	       as the filehandle name.	For example, the default format	name
	       for the "STDOUT"	filehandle is just "STDOUT".

	       Mnemonic: brother to $^.

   Error Variables
       The variables $@, $!, $^E, and $? contain information about different
       types of	error conditions that may appear during	execution of a Perl
       program.	 The variables are shown ordered by the	"distance" between the
       subsystem which reported	the error and the Perl process.	 They
       correspond to errors detected by	the Perl interpreter, C	library,
       operating system, or an external	program, respectively.

       To illustrate the differences between these variables, consider the
       following Perl expression, which	uses a single-quoted string.  After
       execution of this statement, perl may have set all four special error
       variables:

	   eval	q{
	       open my $pipe, "/cdrom/install |" or die	$!;
	       my @res = <$pipe>;
	       close $pipe or die "bad pipe: $?, $!";
	   };

       When perl executes the "eval()" expression, it translates the "open()",
       "<PIPE>", and "close" calls in the C run-time library and thence	to the
       operating system	kernel.	 perl sets $! to the C library's "errno" if
       one of these calls fails.

       $@ is set if the	string to be "eval"-ed did not compile (this may
       happen if "open"	or "close" were	imported with bad prototypes), or if
       Perl code executed during evaluation "die()"d.  In these	cases the
       value of	$@ is the compile error, or the	argument to "die" (which will
       interpolate $! and $?).	(See also Fatal, though.)

       Under a few operating systems, $^E may contain a	more verbose error
       indicator, such as in this case,	"CDROM tray not	closed."  Systems that
       do not support extended error messages leave $^E	the same as $!.

       Finally,	$? may be set to a non-0 value if the external program
       /cdrom/install fails.  The upper	eight bits reflect specific error
       conditions encountered by the program (the program's "exit()" value).
       The lower eight bits reflect mode of failure, like signal death and
       core dump information.  See wait(2) for details.	 In contrast to	$! and
       $^E, which are set only if an error condition is	detected, the variable
       $? is set on each "wait"	or pipe	"close", overwriting the old value.
       This is more like $@, which on every "eval()" is	always set on failure
       and cleared on success.

       For more	details, see the individual descriptions at $@,	$!, $^E, and
       $?.

       ${^CHILD_ERROR_NATIVE}
	       The native status returned by the last pipe close, backtick
	       ("``") command, successful call to "wait()" or "waitpid()", or
	       from the	"system()" operator.  On POSIX-like systems this value
	       can be decoded with the WIFEXITED, WEXITSTATUS, WIFSIGNALED,
	       WTERMSIG, WIFSTOPPED, WSTOPSIG and WIFCONTINUED functions
	       provided	by the POSIX module.

	       Under VMS this reflects the actual VMS exit status; i.e.	it is
	       the same	as $? when the pragma "use vmsish 'status'" is in
	       effect.

	       This variable was added in Perl v5.10.0.

       $EXTENDED_OS_ERROR
       $^E     Error information specific to the current operating system.  At
	       the moment, this	differs	from "$!" under	only VMS, OS/2,	and
	       Win32 (and for MacPerl).	 On all	other platforms, $^E is	always
	       just the	same as	$!.

	       Under VMS, $^E provides the VMS status value from the last
	       system error.  This is more specific information	about the last
	       system error than that provided by $!.  This is particularly
	       important when $!  is set to EVMSERR.

	       Under OS/2, $^E is set to the error code	of the last call to
	       OS/2 API	either via CRT,	or directly from perl.

	       Under Win32, $^E	always returns the last	error information
	       reported	by the Win32 call "GetLastError()" which describes the
	       last error from within the Win32	API.  Most Win32-specific code
	       will report errors via $^E.  ANSI C and Unix-like calls set
	       "errno" and so most portable Perl code will report errors via
	       $!.

	       Caveats mentioned in the	description of "$!" generally apply to
	       $^E, also.

	       This variable was added in Perl 5.003.

	       Mnemonic: Extra error explanation.

       $EXCEPTIONS_BEING_CAUGHT
       $^S     Current state of	the interpreter.

		       $^S	   State
		       ---------   -------------------------------------
		       undef	   Parsing module, eval, or main program
		       true (1)	   Executing an	eval
		       false (0)   Otherwise

	       The first state may happen in $SIG{__DIE__} and $SIG{__WARN__}
	       handlers.

	       The English name	$EXCEPTIONS_BEING_CAUGHT is slightly
	       misleading, because the "undef" value does not indicate whether
	       exceptions are being caught, since compilation of the main
	       program does not	catch exceptions.

	       This variable was added in Perl 5.004.

       $WARNING
       $^W     The current value of the	warning	switch,	initially true if -w
	       was used, false otherwise, but directly modifiable.

	       See also	warnings.

	       Mnemonic: related to the	-w switch.

       ${^WARNING_BITS}
	       The current set of warning checks enabled by the	"use warnings"
	       pragma.	It has the same	scoping	as the $^H and "%^H"
	       variables.  The exact values are	considered internal to the
	       warnings	pragma and may change between versions of Perl.

	       This variable was added in Perl v5.6.0.

       $OS_ERROR
       $ERRNO
       $!      When referenced,	$! retrieves the current value of the C
	       "errno" integer variable.  If $!	is assigned a numerical	value,
	       that value is stored in "errno".	 When referenced as a string,
	       $! yields the system error string corresponding to "errno".

	       Many system or library calls set	"errno"	if they	fail, to
	       indicate	the cause of failure.  They usually do not set "errno"
	       to zero if they succeed.	 This means "errno", hence $!, is
	       meaningful only immediately after a failure:

		   if (open my $fh, "<", $filename) {
			       # Here $! is meaningless.
			       ...
		   }
		   else	{
			       # ONLY here is $! meaningful.
			       ...
			       # Already here $! might be meaningless.
		   }
		   # Since here	we might have either success or	failure,
		   # $!	is meaningless.

	       Here, meaningless means that $! may be unrelated	to the outcome
	       of the "open()" operator.  Assignment to	$! is similarly
	       ephemeral.  It can be used immediately before invoking the
	       "die()" operator, to set	the exit value,	or to inspect the
	       system error string corresponding to error n, or	to restore $!
	       to a meaningful state.

	       Mnemonic: What just went	bang?

       %OS_ERROR
       %ERRNO
       %!      Each element of "%!" has	a true value only if $!	is set to that
	       value.  For example, $!{ENOENT} is true if and only if the
	       current value of	$! is "ENOENT";	that is, if the	most recent
	       error was "No such file or directory" (or its moral equivalent:
	       not all operating systems give that exact error,	and certainly
	       not all languages).  The	specific true value is not guaranteed,
	       but in the past has generally been the numeric value of $!.  To
	       check if	a particular key is meaningful on your system, use
	       "exists $!{the_key}"; for a list	of legal keys, use "keys %!".
	       See Errno for more information, and also	see "$!".

	       This variable was added in Perl 5.005.

       $CHILD_ERROR
       $?      The status returned by the last pipe close, backtick ("``")
	       command,	successful call	to "wait()" or "waitpid()", or from
	       the "system()" operator.	 This is just the 16-bit status	word
	       returned	by the traditional Unix	"wait()" system	call (or else
	       is made up to look like it).  Thus, the exit value of the
	       subprocess is really ("$? >> 8"), and "$? & 127"	gives which
	       signal, if any, the process died	from, and "$? &	128" reports
	       whether there was a core	dump.

	       Additionally, if	the "h_errno" variable is supported in C, its
	       value is	returned via $?	if any "gethost*()" function fails.

	       If you have installed a signal handler for "SIGCHLD", the value
	       of $? will usually be wrong outside that	handler.

	       Inside an "END" subroutine $? contains the value	that is	going
	       to be given to "exit()".	 You can modify	$? in an "END"
	       subroutine to change the	exit status of your program.  For
	       example:

		   END {
		       $? = 1 if $? == 255;  # die would make it 255
		   }

	       Under VMS, the pragma "use vmsish 'status'" makes $? reflect
	       the actual VMS exit status, instead of the default emulation of
	       POSIX status; see "$?" in perlvms for details.

	       Mnemonic: similar to sh and ksh.

       $EVAL_ERROR
       $@      The Perl	error from the last "eval" operator, i.e. the last
	       exception that was caught.  For "eval BLOCK", this is either a
	       runtime error message or	the string or reference	"die" was
	       called with.  The "eval STRING" form also catches syntax	errors
	       and other compile time exceptions.

	       If no error occurs, "eval" sets $@ to the empty string.

	       Warning messages	are not	collected in this variable.  You can,
	       however,	set up a routine to process warnings by	setting
	       $SIG{__WARN__} as described in "%SIG".

	       Mnemonic: Where was the error "at"?

   Variables related to	the interpreter	state
       These variables provide information about the current interpreter
       state.

       $COMPILING
       $^C     The current value of the	flag associated	with the -c switch.
	       Mainly of use with -MO=... to allow code	to alter its behavior
	       when being compiled, such as for	example	to "AUTOLOAD" at
	       compile time rather than	normal,	deferred loading.  Setting
	       "$^C = 1" is similar to calling "B::minus_c".

	       This variable was added in Perl v5.6.0.

       $DEBUGGING
       $^D     The current value of the	debugging flags.  May be read or set.
	       Like its	command-line equivalent, you can use numeric or
	       symbolic	values,	e.g. "$^D = 10"	or "$^D	= "st"".  See
	       "-Dnumber" in perlrun.  The contents of this variable also
	       affects the debugger operation.	See "Debugger Internals" in
	       perldebguts.

	       Mnemonic: value of -D switch.

       ${^ENCODING}
	       This variable is	no longer supported.

	       It used to hold the object reference to the "Encode" object
	       that was	used to	convert	the source code	to Unicode.

	       Its purpose was to allow	your non-ASCII Perl scripts not	to
	       have to be written in UTF-8; this was useful before editors
	       that worked on UTF-8 encoded text were common, but that was
	       long ago.  It caused problems, such as affecting	the operation
	       of other	modules	that weren't expecting it, causing general
	       mayhem.

	       If you need something like this functionality, it is
	       recommended that	use you	a simple source	filter,	such as
	       Filter::Encoding.

	       If you are coming here because code of yours is being adversely
	       affected	by someone's use of this variable, you can usually
	       work around it by doing this:

		local ${^ENCODING};

	       near the	beginning of the functions that	are getting broken.
	       This undefines the variable during the scope of execution of
	       the including function.

	       This variable was added in Perl 5.8.2 and removed in 5.26.0.
	       Setting it to anything other than "undef" was made fatal	in
	       Perl 5.28.0.

       ${^GLOBAL_PHASE}
	       The current phase of the	perl interpreter.

	       Possible	values are:

	       CONSTRUCT
		       The "PerlInterpreter*" is being constructed via
		       "perl_construct".  This value is	mostly there for
		       completeness and	for use	via the	underlying C variable
		       "PL_phase".  It's not really possible for Perl code to
		       be executed unless construction of the interpreter is
		       finished.

	       START   This is the global compile-time.	 That includes,
		       basically, every	"BEGIN"	block executed directly	or
		       indirectly from during the compile-time of the top-
		       level program.

		       This phase is not called	"BEGIN"	to avoid confusion
		       with "BEGIN"-blocks, as those are executed during
		       compile-time of any compilation unit, not just the top-
		       level program.  A new, localised	compile-time entered
		       at run-time, for	example	by constructs as "eval "use
		       SomeModule"" are	not global interpreter phases, and
		       therefore aren't	reflected by "${^GLOBAL_PHASE}".

	       CHECK   Execution of any	"CHECK"	blocks.

	       INIT    Similar to "CHECK", but for "INIT"-blocks, not "CHECK"
		       blocks.

	       RUN     The main	run-time, i.e. the execution of
		       "PL_main_root".

	       END     Execution of any	"END" blocks.

	       DESTRUCT
		       Global destruction.

	       Also note that there's no value for UNITCHECK-blocks.  That's
	       because those are run for each compilation unit individually,
	       and therefore is	not a global interpreter phase.

	       Not every program has to	go through each	of the possible
	       phases, but transition from one phase to	another	can only
	       happen in the order described in	the above list.

	       An example of all of the	phases Perl code can see:

		   BEGIN { print "compile-time:	${^GLOBAL_PHASE}\n" }

		   INIT	 { print "init-time: ${^GLOBAL_PHASE}\n" }

		   CHECK { print "check-time: ${^GLOBAL_PHASE}\n" }

		   {
		       package Print::Phase;

		       sub new {
			   my ($class, $time) =	@_;
			   return bless	\$time,	$class;
		       }

		       sub DESTROY {
			   my $self = shift;
			   print "$$self: ${^GLOBAL_PHASE}\n";
		       }
		   }

		   print "run-time: ${^GLOBAL_PHASE}\n";

		   my $runtime = Print::Phase->new(
		       "lexical	variables are garbage collected	before END"
		   );

		   END	 { print "end-time: ${^GLOBAL_PHASE}\n"	}

		   our $destruct = Print::Phase->new(
		       "package	variables are garbage collected	after END"
		   );

	       This will print out

		   compile-time: START
		   check-time: CHECK
		   init-time: INIT
		   run-time: RUN
		   lexical variables are garbage collected before END: RUN
		   end-time: END
		   package variables are garbage collected after END: DESTRUCT

	       This variable was added in Perl 5.14.0.

       $^H     WARNING:	This variable is strictly for internal use only.  Its
	       availability, behavior, and contents are	subject	to change
	       without notice.

	       This variable contains compile-time hints for the Perl
	       interpreter.  At	the end	of compilation of a BLOCK the value of
	       this variable is	restored to the	value when the interpreter
	       started to compile the BLOCK.

	       When perl begins	to parse any block construct that provides a
	       lexical scope (e.g., eval body, required	file, subroutine body,
	       loop body, or conditional block), the existing value of $^H is
	       saved, but its value is left unchanged.	When the compilation
	       of the block is completed, it regains the saved value.  Between
	       the points where	its value is saved and restored, code that
	       executes	within BEGIN blocks is free to change the value	of
	       $^H.

	       This behavior provides the semantic of lexical scoping, and is
	       used in,	for instance, the "use strict" pragma.

	       The contents should be an integer; different bits of it are
	       used for	different pragmatic flags.  Here's an example:

		   sub add_100 { $^H |=	0x100 }

		   sub foo {
		       BEGIN { add_100() }
		       bar->baz($boon);
		   }

	       Consider	what happens during execution of the BEGIN block.  At
	       this point the BEGIN block has already been compiled, but the
	       body of "foo()" is still	being compiled.	 The new value of $^H
	       will therefore be visible only while the	body of	"foo()"	is
	       being compiled.

	       Substitution of "BEGIN {	add_100() }" block with:

		   BEGIN { require strict; strict->import('vars') }

	       demonstrates how	"use strict 'vars'" is implemented.  Here's a
	       conditional version of the same lexical pragma:

		   BEGIN {
		       require strict; strict->import('vars') if $condition
		   }

	       This variable was added in Perl 5.003.

       %^H     The "%^H" hash provides the same	scoping	semantic as $^H.  This
	       makes it	useful for implementation of lexically scoped pragmas.
	       See perlpragma.	 All the entries are stringified when accessed
	       at runtime, so only simple values can be	accommodated.  This
	       means no	pointers to objects, for example.

	       When putting items into "%^H", in order to avoid	conflicting
	       with other users	of the hash there is a convention regarding
	       which keys to use.  A module should use only keys that begin
	       with the	module's name (the name	of its main package) and a "/"
	       character.  For example,	a module "Foo::Bar" should use keys
	       such as "Foo::Bar/baz".

	       This variable was added in Perl v5.6.0.

       ${^OPEN}
	       An internal variable used by PerlIO.  A string in two parts,
	       separated by a "\0" byte, the first part	describes the input
	       layers, the second part describes the output layers.

	       This is the mechanism that applies the lexical effects of the
	       open pragma, and	the main program scope effects of the "io" or
	       "D" options for the -C command-line switch and PERL_UNICODE
	       environment variable.

	       The functions "accept()", "open()", "pipe()", "readpipe()" (as
	       well as the related "qx"	and "`STRING`" operators), "socket()",
	       "socketpair()", and "sysopen()" are affected by the lexical
	       value of	this variable.	The implicit "ARGV" handle opened by
	       "readline()" (or	the related "<>" and "<<>>" operators) on
	       passed filenames	is also	affected (but not if it	opens
	       "STDIN").  If this variable is not set, these functions will
	       set the default layers as described in "Defaults	and how	to
	       override	them" in PerlIO.

	       "open()"	ignores	this variable (and the default layers) when
	       called with 3 arguments and explicit layers are specified.
	       Indirect	calls to these functions via modules like IO::Handle
	       are not affected	as they	occur in a different lexical scope.
	       Directory handles such as opened	by "opendir()" are not
	       currently affected.

	       This variable was added in Perl v5.8.0.

       $PERLDB
       $^P     The internal variable for debugging support.  The meanings of
	       the various bits	are subject to change, but currently indicate:

	       0x01  Debug subroutine enter/exit.

	       0x02  Line-by-line debugging.  Causes "DB::DB()"	subroutine to
		     be	called for each	statement executed.  Also causes
		     saving source code	lines (like 0x400).

	       0x04  Switch off	optimizations.

	       0x08  Preserve more data	for future interactive inspections.

	       0x10  Keep info about source lines on which a subroutine	is
		     defined.

	       0x20  Start with	single-step on.

	       0x40  Use subroutine address instead of name when reporting.

	       0x80  Report "goto &subroutine" as well.

	       0x100 Provide informative "file"	names for evals	based on the
		     place they	were compiled.

	       0x200 Provide informative names to anonymous subroutines	based
		     on	the place they were compiled.

	       0x400 Save source code lines into "@{"_<$filename"}".

	       0x800 When saving source, include evals that generate no
		     subroutines.

	       0x1000
		     When saving source, include source	that did not compile.

	       Some bits may be	relevant at compile-time only, some at run-
	       time only.  This	is a new mechanism and the details may change.
	       See also	perldebguts.

       ${^TAINT}
	       Reflects	if taint mode is on or off.  1 for on (the program was
	       run with	-T), 0 for off,	-1 when	only taint warnings are
	       enabled (i.e. with -t or	-TU).

	       This variable is	read-only.

	       This variable was added in Perl v5.8.0.

       ${^SAFE_LOCALES}
	       Reflects	if safe	locale operations are available	to this	perl
	       (when the value is 1) or	not (the value is 0).  This variable
	       is always 1 if the perl has been	compiled without threads.  It
	       is also 1 if this perl is using thread-safe locale operations.
	       Note that an individual thread may choose to use	the global
	       locale (generally unsafe) by calling "switch_to_global_locale"
	       in perlapi.  This variable currently is still set to 1 in such
	       threads.

	       This variable is	read-only.

	       This variable was added in Perl v5.28.0.

       ${^UNICODE}
	       Reflects	certain	Unicode	settings of Perl.  See perlrun
	       documentation for the "-C" switch for more information about
	       the possible values.

	       This variable is	set during Perl	startup	and is thereafter
	       read-only.

	       This variable was added in Perl v5.8.2.

       ${^UTF8CACHE}
	       This variable controls the state	of the internal	UTF-8 offset
	       caching code.  1	for on (the default), 0	for off, -1 to debug
	       the caching code	by checking all	its results against linear
	       scans, and panicking on any discrepancy.

	       This variable was added in Perl v5.8.9.	It is subject to
	       change or removal without notice, but is	currently used to
	       avoid recalculating the boundaries of multi-byte	UTF-8-encoded
	       characters.

       ${^UTF8LOCALE}
	       This variable indicates whether a UTF-8 locale was detected by
	       perl at startup.	 This information is used by perl when it's in
	       adjust-utf8ness-to-locale mode (as when run with	the "-CL"
	       command-line switch); see perlrun for more info on this.

	       This variable was added in Perl v5.8.8.

   Deprecated and removed variables
       Deprecating a variable announces	the intent of the perl maintainers to
       eventually remove the variable from the language.  It may still be
       available despite its status.  Using a deprecated variable triggers a
       warning.

       Once a variable is removed, its use triggers an error telling you the
       variable	is unsupported.

       See perldiag for	details	about error messages.

       $#      $# was a	variable that could be used to format printed numbers.
	       After a deprecation cycle, its magic was	removed	in Perl
	       v5.10.0 and using it now	triggers a warning: "$#	is no longer
	       supported".

	       This is not the sigil you use in	front of an array name to get
	       the last	index, like $#array.  That's still how you get the
	       last index of an	array in Perl.	The two	have nothing to	do
	       with each other.

	       Deprecated in Perl 5.

	       Removed in Perl v5.10.0.

       $*      $* was a	variable that you could	use to enable multiline
	       matching.  After	a deprecation cycle, its magic was removed in
	       Perl v5.10.0.  Using it now triggers a warning: "$* is no
	       longer supported".  You should use the "/s" and "/m" regexp
	       modifiers instead.

	       Deprecated in Perl 5.

	       Removed in Perl v5.10.0.

       $[      This variable stores the	index of the first element in an
	       array, and of the first character in a substring.  The default
	       is 0, but you could theoretically set it	to 1 to	make Perl
	       behave more like	awk (or	Fortran) when subscripting and when
	       evaluating the index() and substr() functions.

	       As of release 5 of Perl,	assignment to $[ is treated as a
	       compiler	directive, and cannot influence	the behavior of	any
	       other file.  (That's why	you can	only assign compile-time
	       constants to it.)  Its use is highly discouraged.

	       Prior to	Perl v5.10.0, assignment to $[ could be	seen from
	       outer lexical scopes in the same	file, unlike other compile-
	       time directives (such as	strict).  Using	local()	on it would
	       bind its	value strictly to a lexical block.  Now	it is always
	       lexically scoped.

	       As of Perl v5.16.0, it is implemented by	the arybase module.

	       As of Perl v5.30.0, or under "use v5.16", or "no	feature
	       "array_base"", $[ no longer has any effect, and always contains
	       0.  Assigning 0 to it is	permitted, but any other value will
	       produce an error.

	       Mnemonic: [ begins subscripts.

	       Deprecated in Perl v5.12.0.

perl v5.32.0			  2020-06-14			    PERLVAR(1)

NAME | DESCRIPTION | SPECIAL VARIABLES

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