如何将系统命令的结果存储在Perl变量中？ [英] How can I store the result of a system command in a Perl variable?

问题描述

$ cat test.pl
my $pid = 5892;
my $not = system("top -H -p $pid -n 1 | grep myprocess | wc -l");
print "not = $not\n";
$ perl test.pl
11
not = 0
$

我想捕获结果ie 11 到一个变量。我该如何做？

I want to capture the result i.e. 11 into a variable. How can I do that?

推荐答案

从 Perlfaq8 ：

您混淆了 system（）和反引号（``）。 system（）运行命令并返回退出状态信息（作为16位值：低7位是进程死亡的信号，如果有的话，高8位是实际退出值）。反引号（``）运行一个命令，并返回它发送到STDOUT。

You're confusing the purpose of system() and backticks (``). system() runs a command and returns exit status information (as a 16 bit value: the low 7 bits are the signal the process died from, if any, and the high 8 bits are the actual exit value). Backticks (``) run a command and return what it sent to STDOUT.

$exit_status   = system("mail-users");
    $output_string = `ls`;

有很多方法可以从Perl执行外部命令。最常见的含义是：

There are many ways to execute external commands from Perl. The most commons with their meanings are:

• exec ：您不想返回到
  调用perl脚本


• 反引号 ：您要捕获
  命令的输出


• 打开： / strong>您希望将命令（作为
  输入或输出）转换为您的脚本

• system() : you want to execute a command and don't want to capture its output
• exec: you don't want to return to the calling perl script
• backticks : you want to capture the output of the command
• open: you want to pipe the command (as input or output) to your script

=http://perldoc.perl.org/perlfaq8.html#How-can-I-capture-STDERR-from-an-external-command%3f>如何从外部命令捕获STDERR？

Also see How can I capture STDERR from an external command?

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