从Perl调用系统命令 [英] Calling system commands from Perl

问题描述

在我们较旧版本的代码中，我们从Perl中调用以进行LDAP搜索，如下所示:

In an older version of our code, we called out from Perl to do an LDAP search as follows:

# Pass the base DN in via the ldapsearch-specific environment variable 
# (rather than as the "-b" paramater) to avoid problems of shell 
# interpretation of special characters in the DN.
$ENV{LDAP_BASEDN} = $ldn;

$lcmd = "ldapsearch -x -T -1 -h $gLdapServer" .
        <snip>
        " > $lworkfile 2>&1";
system($lcmd);

if (($? != 0) || (! -e "$lworkfile"))
{
  # Handle the error
}

上面的代码将导致LDAP搜索成功，并且该搜索的输出将在文件$lworkfile中.

The code above would result in a successful LDAP search, and the output of that search would be in the file $lworkfile.

不幸的是，我们最近在此服务器上重新配置了openldap，以便在/etc/openldap/ldap.conf和/etc/ldap.conf中指定"BASE DC =.该更改似乎意味着ldapsearch忽略了LDAP_BASEDN环境变量，因此我的ldapsearch失败了.

Unfortunately, we recently reconfigured openldap on this server so that a "BASE DC=" is specified in /etc/openldap/ldap.conf and /etc/ldap.conf. That change seems to mean ldapsearch ignores the LDAP_BASEDN environment variable, and so my ldapsearch fails.

我已经尝试了几种不同的修复方法，但到目前为止都没有成功:

I've tried a couple of different fixes but without success so far:

(1)我尝试返回对ldapsearch使用"-b"参数，但转义了外壳元字符.我开始编写转义代码:

(1) I tried going back to using the "-b" argument to ldapsearch, but escaping the shell metacharacters. I started writing the escaping code:

my $ldn_escaped = $ldn;
$ldn_escaped =~ s/\/\\/g;
$ldn_escaped =~ s/`/\`/g;
$ldn_escaped =~ s/$/\$/g;
$ldn_escaped =~ s/"/\"/g;

这引发了一些Perl错误，因为我没有在Perl中正确地转义那些正则表达式(行号与带有反引号的正则表达式匹配).

That threw up some Perl errors because I haven't escaped those regexes properly in Perl (the line number matches the regex with the backticks in).

Backticks found where operator expected at /tmp/mycommand line 404, at end of line

与此同时，我开始怀疑这种方法，并寻求一种更好的方法.

At the same time I started to doubt this approach and looked for a better one.

(2)然后，我看到了一些Stackoverflow问题(此处和此处)建议更好的解决方案.

(2) I then saw some Stackoverflow questions (here and here) that suggested a better solution.

这是代码:

print("Processing...");

# Pass the arguments to ldapsearch by invoking open() with an array.
# This ensures the shell does NOT interpret shell metacharacters.
my(@cmd_args) = ("-x", "-T", "-1", "-h", "$gLdapPool",
                 "-b", "$ldn",
                 <snip>
                );

$lcmd = "ldapsearch";

open my $lldap_output, "-|", $lcmd, @cmd_args;

while (my $lline = <$lldap_output>)
{
  # I can parse the contents of my file fine
}

$lldap_output->close;

我在方法(2)中遇到的两个问题是:

The two problems I am having with approach (2) are:

a)用参数数组调用open或system不允许我将> $lworkfile 2>&1传递给命令，因此我无法停止将ldapsearch输出发送到屏幕，这会使我的输出看起来很丑陋:

a) Calling open or system with an array of arguments does not let me pass > $lworkfile 2>&1 to the command, so I can't stop the ldapsearch output being sent to screen, which makes my output look ugly:

Processing...ldap_bind: Success (0)
        additional info: Success

b)我不知道如何选择传递给open的文件句柄的位置(即路径和文件名)，即我不知道$lldap_output在哪里.我可以移动/重命名它，还是检查它以找出它在哪里(或者它实际上没有保存到磁盘上)?

b) I can't figure out how to choose which location (i.e. path and file name) to the file handle passed to open, i.e. I don't know where $lldap_output is. Can I move/rename it, or inspect it to find out where it is (or is it not actually saved to disk)?

基于(2)的问题，这使我认为我应该回到方法(1)，但是我不太确定该怎么做

Based on the problems with (2), this makes me think I should return back to approach (1), but I'm not quite sure how to

推荐答案

一种方法是使用 IPC::Open3 使您的Perl代码能够处理外部程序的stdout和stderr流.

One approach would be to use IPC::Open3 to enable your Perl code to handle both the stdout and stderr streams of your external program.

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