Perl pipe用法及代碼示例

描述

該函數打開一對連接的通信管道：READHANDLE 用於讀取，WRITEHANDLE 用於寫入。您可能需要設置 $|在每個命令後刷新您的 WRITEHANDLE。

用法

以下是此函數的簡單語法 -

pipe READHANDLE, WRITEHANDLE

返回值

此函數在失敗時返回 0，成功時返回 1。

示例

以下是顯示其基本用法的示例代碼 -

#!/usr/bin/perl -w

use IO::Handle;

pipe(PARENTREAD, PARENTWRITE);
pipe(CHILDREAD, CHILDWRITE);

PARENTWRITE->autoflush(1);
CHILDWRITE->autoflush(1);

if ($child = fork) { # Parent code
   close CHILDREAD; # We don't need these in the parent
   close PARENTWRITE;
   print CHILDWRITE "34+56;\n";
   chomp($result = <PARENTREAD>);
   print "Got a value of $result from child\n";
   close PARENTREAD;
   close CHILDWRITE;
   waitpid($child,0);
} else {
   close PARENTREAD; # We don't need these in the child
   close CHILDWRITE;
   chomp($calculation = <CHILDREAD>);
   print "Got $calculation\n";
   $result = eval "$calculation";
   print PARENTWRITE "$result\n";
   close CHILDREAD;
   close PARENTWRITE;
   exit;
}

它會產生以下結果： 可以看到計算被發送到 CHILDWRITE，然後由孩子從 CHILDREAD 讀取。然後計算結果並通過 PARENTWRITE 發送回父級，父級從 PARENTREAD 讀取結果。

Got 34+56;
Got a value of 90 from child