如果将任何内容写入STDERR，如何运行系统命令而死? [英] How can I run a system command and die if anything is written to STDERR?

问题描述

我正在编写一个使用外部脚本的Perl脚本.外部脚本必须从特定目录运行，因此我发现以下有用:

I'm writing a Perl script which uses an external script. The external script must run from a specific directory so I found the following useful:

use IPC::System::Simple qw(capture);

my @args = ('external script path...', 'arg1', ...);
my $out = capture( [0], "cd $dir ; @args" );

有时，外部脚本会将内容写入STDERR，但仍返回0.我希望捕获这些时间和confess(或die).由于我无法控制外部脚本的返回值，因此我想也许可以捕获其STDERR，所以我将得到以下内容:

Sometimes the external script writes stuff to STDERR but still returns 0. I wish to capture these times and confess (or die). Since I don't control the return value of the external script, I thought maybe I could capture its STDERR so I'll have something like this:

my ($out, $err) = cool_capture( [0], "cd $dir ; @args" );
say "Output was: $out";
if ($err) {
 die "Error: this was written to STDERR: $err";
}

我该怎么办?

推荐答案

这是假定test_app是一个将一行输出到stdout并将一行输出到stderr的程序:

Presuming test_app is a program that outputs one line to stdout and one line to stderr:

use IPC::Open3;
use Symbol 'gensym';

my($wtr, $rdr, $err);
$err = gensym;

my $pid = open3($wtr, $rdr, $err, 'test_app');

waitpid($pid, 0);
my $status = $? >> 8;

my $stdout = <$rdr>;
my $stderr = <$err>;

print "out output: $stdout\n";
print "err output: $stderr\n";

print "Exit code: $status\n";

根据更新的请求，其中包括捕获退出代码.您可能还问过perldoc IPC::Open3上面写着

Per the request updated to include capturing the exit code. You could also have asked perldoc IPC::Open3 which says

waitpid( $pid, 0 );
my $child_exit_status = $? >> 8;

对于它的警告和注意事项，无论如何都应该阅读.

And which you should read anyway for its cautions and caveats.

这篇关于如果将任何内容写入STDERR，如何运行系统命令而死?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！