[NPWP笔记]从管道中读取数据

使用后缀“|”操作实现从标准输入设备中读取内容。

#!/usr/bin/perl

use strict;

my %who;

open(WHOFH,"who |") or die "can not open who:$!";

while(<WHOFH>){

next unless /^(/S+)/;

$who{$1}++;

}

foreach (sort{$who{$b} <=> $who{$a}} keys %who){

printf "%10s %d/n",$_,$who{$_};

}

close WHOFH or die "close error:$!";

在Linux运行结果

landopen@server01:~$ perl whos_there.pl

landopen 1

dinwen 1