Perlの特殊変数

Perl predefined variables

Perl の特殊変数は検索しにくくて解説が見つけにくかったりします。

しかし、そんなときこそ perldoc コマンド。
以下のように -v で特殊変数の個別解説が読めます。

$ perldoc -v '$|'
    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.  (Mnemonic: when you want your pipes to
            be piping hot.)

特殊変数の全体をまとめて読むには perlvar が最適です。

$ perldoc perlvar

Perl 特殊変数 一行解説