如何在Perl中读取外部命令的错误输出？ [英] How can I read the error output of external commands in Perl?

问题描述

作为较大的Perl程序的一部分，我正在对照参考文件检查文件夹中输入文件的 diff 命令的输出，其中空白输出（匹配项）是传递的结果，而diff的任何输出都是失败的结果。

As part of a larger Perl program, I am checking the outputs of diff commands of input files in a folder against reference files, where a blank output (a match) is a passing result, and any output from diff is a fail result.

问题是，如果目标文件夹的文件数不足，则diff例外

The issue is, if the target folder is short on the number of expected files, the exception diff throws doesn't come as output, creating false passes.

输出示例：

diff: /testfolder/Test-02/test-output.2: No such file or directory

Test-01：通过

Test-01: PASS

Test-02：通过

Test-02: PASS

代码如下：

$command = "(diff call on 2 files)";
my @output = `$command`;
print "Test-02: ";
$toPrint = "PASS";
foreach my $x (@output) {
    if ($x =~ /./) {
        $toPrint = "FAIL";
    }
}

如果存在以下情况，这是一项失败的快速黑客工作 diff 调用的任何输出。有没有办法检查反引号中调用的命令引发的异常？

This is a quick hackery job to fail if there is any output from the diff call. Is there a way to check for exceptions thrown by the command called in the backticks?

推荐答案

程序本身不能抛出 exceptions，但它们可以返回非零错误代码。您可以使用$？在Perl中检查带有反引号或 system（）运行的程序的错误代码：

Programs themselves can't throw "exceptions", but they can return nonzero error codes. You can check the error code of a program run with backticks or system() in Perl using $?:

$toPrint = "FAIL" if $?;

（在测试 @output 。）

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