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Variable English Name Description
$_ $ARG default input and pattern-searching space
$& $MATCH string matched by the last successful pattern match
$` $PREMATCH string preceding whatever was matched by the last successful pattern
$' $POSTMATCH string following whatever was matched by the last successful pattern
$+ $LAST_PAREN_MATCH last bracket matched by the last search pattern
$* $MULTILINE_MATCHING Perl 5 does multi-line matching within a string if it is 1(the default is 0)
$. $INPUT_LINE_NUMBER current input line number from the last file handle read
$/ $INPUT_RECORD_SEPARATOR The input record separator (newline by default)
$| $OUTPUT_AUTOFLUSH If it is nonzero, forces a flush after every write or print on the currently selected output device (the default is 0)
$, $OUTPUT_FIELD_SEPARATOR field separator for the print function
$\ $OUTPUT_RECORD_SEPARATOR record separator for the print function
$" $LIST_SEPARATOR list separator for the print function
$; $SUBSCRIPT_SEPARATOR subscript separator for multidimensional array emulation
$# $OFMT format for printed numbers
$% $FORMAT_PAGE_NUMBER page number for file handle output
$= $FORMAT_LINES_PER_PAGE page length for file handle output
$- $FORMAT_LINES_LEFT number of lines left on the page
$~ $FORMAT_NAME current format
$^ $FORMAT_TOP_NAME current top-of-page format
$: $FORMAT_LINE_BREAK_CHARACTERS characters after which a string may be separated to fill continuation fields
$^L $FORMAT_FORMFEED The value a format will output for each form feed
$^A $ACCUMULATOR write() accumulator for format() lines
$? $CHILD_ERROR status returned by the last pipe close, backtick (``) command, or system() operator
$! $ERRNO current numeric or string value of error number
$^E $EXTENDED_OS_ERROR Error information specific to the current operating system
$@ $EVAL_ERROR Perl syntax error message from the last eval() command
$$ $PROCESS_ID process number of the Perl running this script
$< $REAL_USER_ID uid of this process
$> $EFFECTIVE_USER_ID effective uid of this process
$( $REAL_GROUP_ID real gid of this process
$) $EFFECTIVE_GROUP_ID effective gid of this process
$0 $PROGRAM_NAME name of the file used to invoke the executing program
$[ index of the first element in an array and of the first character in a substring
$] $PERL_VERSION version and patch level of the Perl interpreter
$^D $DEBUGGING value of the debugging flags
$^F $SYSTEM_FD_MAX maximum system file descriptor
$^H set of syntax checks enabled by use strict and other pragmas
$^I $INPLACE_EDIT value of the in-place edit extension
$^M An emergency pool of allocated memory, used after an out-of-memory condition for printing error messages
$^O $OSNAME name of the operating system under which this copy of Perl was built, as determined during the configuration process
$^P $PERLDB internal variable for debugging support
$^R The result of evaluation of the last successful regular expression
$^S state of the interpreter
$^T $BASETIME The time at which the script began running, in seconds since the epoch
$^W $WARNING The current value of the warning switch, either true or false
$^X $EXECUTABLE_NAME Perl binary
$ARGV current file when reading from <>
@ARGV An array that contains the command-line arguments
@INC An array that contains the list of places to look for Perl scripts to be evaluated by the do EXPR, require, or use constructs (initially consists of the arguments to any -I command-line switches, followed by the default Perl library, followed by ``.'', which represents the current directory)
@_ Within a subroutine, an array that contains the parameters passed to that subroutine
%INC A hash that contains entries for each filename that has been included via do or require (the key is the filename you specified, and the value is the location of the file actually found)
%ENV A hash that contains your current environment (setting a value in %ENV changes the environment for child processes)
%SIG A hash used to set signal handlers for various signals
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