Perl 管道函式

說明

此函式開啟一對已連線的通訊管道：READHANDLE 用於讀取和 WRITEHANDLE 用於寫入。您可能需要將 $| 設定為在每條命令後重新整理您的 WRITEHANDLE。

語法

以下為此函式的簡單語法 −

pipe READHANDLE, WRITEHANDLE

返回值

此函式在失敗時返回 0，在成功時返回 1。

示例

以下是顯示其基本用法的示例程式碼 −

#!/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;
}

它將產生以下結果：您可以看到計算值傳送至 CHILDWRITE，然後子程序從 CHILDREAD 中讀取該值。然後計算結果，並透過 PARENTWRITE 傳送回父程序，父程序從 PARENTREAD 中讀取結果。

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