Special Variables

The following variables are global and should be localized in subroutines:

• $_
• The default input and pattern-searching space.
• $.
• The current input line number of the last filehandle that was read.
• $/
• The input record separator, newline by default. May be multicharacter.
• $,
• The output field separator for the print operator.
• $"
• The separator that joins elements of arrays interpolated in strings.
• $\
• The output record separator for the print operator.
• $#
• The output format for printed numbers. Deprecated.
• $*
• Set to 1 to do multiline matching within strings. Deprecated, see the m and s modifiers in the section called "Search and Replace Functions".
• $?
• The status returned by the last ` ... ` command, pipe close, or system operator.
• $]
• The Perl version number, e.g., 5.001.
• $[
• The index of the first element in an array, and of the first character in a substring. Default is 0. Deprecated.
• $;
• The subscript separator for multidimensional array emulation. Default is "\ 34".
• $!
• If used in a numeric context, yields the current value of errno. If used in a string context, yields the corresponding error string.
• $@
• The Perl error message from the last eval or do expr command.
• $:
• The set of characters after which a string may be broken to fill continuation fields (starting with ^) in a format.
• $0
• The name of the file containing the Perl script being executed. May have a value assigned to it.
• $$
• The process ID of the currently executing Perl program. Altered (in the child process) by fork.
• $<
• The real user ID of this process.
• $>
• The effective user ID of this process.
• $(
• The real group ID of this process.
• $)
• The effective group ID of this process.
• $^A
• The accumulator for formline and write operations.
• $^D
• The debug flags as passed to Perl using -D.
• $^F
• The highest system file descriptor, ordinarily 2.
• $^I
• In-place edit extension as passed to Perl using -i.
• $^L
• Formfeed character used in formats.
• $^P
• Internal debugging flag.
• $^T
• The time (as delivered by time) when the program started. This value is used by the file test operators -M, -A, and -C.
• $^W
• The value of the -w option as passed to Perl.
• $^X
• The name by which the currently executing program was invoked.

The following variables are context dependent and need not be localized:

• $%
• The current page number of the currently selected output channel.
• $=
• The page length of the current output channel. Default is 60 lines.
• $-
• The number of lines remaining on the page.
• $~
• The name of the current report format.
• $^
• The name of the current top-of-page format.
• $|
• If set to nonzero, forces a flush after every write or print on the currently selected output channel. Default is 0.
• $ARGV
• The name of the current file when reading from < >.

The following variables are always local to the current block:

• $&
• The string matched by the last successful pattern match.
• $`
• The string preceding what was matched by the last successful match.
• $'
• The string following what was matched by the last successful match.
• $+
• The last bracket matched by the last search pattern.
• $1...$9...
• Contain the subpatterns from the corresponding sets of parentheses in the last pattern successfully matched. $10... and up are only available if the match contained that many subpatterns.