Common special variables in Perl

Perl built-in Variables

$-Number of printable lines on the current page, part of the perl format system

$! Returns the error code or string based on the context content.

$ "List Separator

$ # Default digital output format when printing numbers

$ Perl interpreter process ID

$ % Current page number of the current output channel

$ & String matching the previous format

$ (Group ID of the current process

$) Valid group ID of the current process

$ * Setting 1 indicates processing the multiline format. It is replaced by the/s and/M modifiers.

$, Delimiter of the current output field

$. Current row number of the last Read File

$/Delimiter of the current input record. The default value is a new line.

$: Character setting. Subsequent strings are separated to fill continuous fields.

$; Delimiter used to simulate multi-dimensional arrays.

$? Returns the status of the last external command.

[Email protected] error message returned by the perl interpreter from the eval statement

$ [Index number of the first element in the array

$ \ Delimiter of the current output record

$] Sub-version number of the perl interpreter

$ ^ Name of the top page output format of the current channel

$ ^ A variables used to save formatted data before printing

$ ^ D debug flag value

$ ^ E Operating System Extension error message in non-Unix environment

$ ^ F maximum file bundle operator Value

$ ^ H check status of the syntax activated by the compiler

$ ^ I built-in control editor Value

$ ^ L form feed sent to the output channel

$ ^ M backup memory pool size

$ ^ O operating system name

$ ^ P specifies the internal variable of the current debugging Value

$ ^ R result of the last evaluation of the regular expression Block

$ ^ S current interpreter status

$ ^ T start from the new century, and the start time of the notebook is calculated in seconds.

$ ^ W current value of the warning Switch

$ ^ X Perl binary executable code name

$ _ Default input/output and format matching space

$ | Controls the buffer of the currently selected output file handle

$ ~ Name of the current report format

$ 'String before matching information in the previous format

$ 'String after matching information in the previous format

$ + The last parenthesis matching the previous regular expression search format

$ <Real id of the user currently executing the interpreter

$ Contains the matching result in parentheses corresponding to the previous Regular Expression

$ = Number of printable rows on the current page

$> Valid user ID of the current process

File name containing the script being executed

$ Argv current file name when reading from the default file handle

% ENV Environment Variable list

% Inc list of files contained through do or require

% Sig signal list and Processing Method

@ _ List of parameters passed to the subroutine

@ Argv: List of command line parameters passed to the script

@ INC: List of directories to be searched during module Import

$-[0] and $ + [0] represent the starting and ending positions of the currently matched Regular Expression in the matched string