如何在 Perl 中找到用户的主目录? [英] How do I find a user's home directory in Perl?

问题描述

我需要检查用户主目录中的文件是否存在，所以使用文件检查:

if ( -e "~/foo.txt" ) {打印是的，它存在！";}

即使在用户的主目录下有一个名为 foo.txt 的文件，Perl 总是抱怨没有这样的文件或目录.当我用 /home/jimmy 替换~"(假设用户是 jimmy)时，Perl 会给出正确的判断.

你能解释一下为什么 "~" 在 Perl 中不起作用并告诉我 Perl 的方法是什么找到用户的主目录?

解决方案

~ 是一个 bash-ism 而不是 perl-ism，这就是它不起作用的原因.鉴于您似乎使用的是 UNIX 类型的系统，最简单的 解决方案可能是使用 $HOME 环境变量，例如:

if ( -e $ENV{"HOME"} . "/foo.txt" ) {打印是的，它存在！";}

是的，我知道用户可以更改他们的 $HOME 环境变量，但我假设他们知道他们在做什么.如果没有，他们应得的一切:-)

如果您想以正确的方式进行操作，您可以查看File::HomeDir，它更了解平台.您可以在以下脚本 chkfile.pl 中看到它的运行情况:

使用 File::HomeDir;$fileSpec = File::HomeDir->my_home ."/foo.txt";如果 ( -e $fileSpec ) {print "是的，它存在！
";} 别的 {print "不，它没有！
";}

和成绩单:

<前>pax$ touch ~/foo.txt ;perl chkfile.pl是的，它存在！pax$ rm -rf ~/foo.txt ;perl chkfile.pl不，它没有！

I need to check whether a file in a user's home directory exists so use file check:

if ( -e "~/foo.txt" ) {
   print "yes, it exists!" ;
}

Even though there is a file called foo.txt under the user's home directory, Perl always complains that there is no such file or directory. When I replace "~" with /home/jimmy (let's say the user is jimmy) then Perl give the right verdict.

Could you explain why "~" dosen't work in Perl and tell me what is Perl's way to find a user's home directory?

解决方案

~ is a bash-ism rather than a perl-ism, which is why it's not working. Given that you seem to be on a UNIX-type system, probably the easiest solution is to use the $HOME environment variable, such as:

if ( -e $ENV{"HOME"} . "/foo.txt" ) {
    print "yes ,it exists!" ;
}

And yes, I know the user can change their $HOME environment variable but then I would assume they know what they're doing. If not, they deserve everything they get :-)

If you want to do it the right way, you can look into File::HomeDir, which is a lot more platform-savvy. You can see it in action in the following script chkfile.pl:

use File::HomeDir;
$fileSpec = File::HomeDir->my_home . "/foo.txt";
if ( -e $fileSpec ) {
    print "Yes, it exists!
";
} else {
    print "No, it doesn't!
";
}

and transcript:

pax$ touch ~/foo.txt ; perl chkfile.pl
Yes, it exists!

pax$ rm -rf ~/foo.txt ; perl chkfile.pl
No, it doesn't!

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