如何从Perl中的目录告诉文件

青旅半醒 2022-12-06 15:41 143阅读 0赞

Let's say you're building a Perl script to traverse a file system and record what it finds. As you open file handles, you need to know if you're dealing with an actual file or with a directory, which you treat differently. You want to glob a directory, so you can continue to recursively parse the filesystem. The quickest way to tell files from directories is to use Perl's built-in [File Test Operators][]. Perl has operators you can use to test different aspects of a file. The -f operator is used to identify regular files rather than directories or other types of files.

假设您正在构建一个Perl脚本来遍历文件系统并记录其发现的内容。 打开文件句柄时，您需要知道要处理的是实际文件还是目录，对它们的处理方式有所不同。 您想要遍历目录，以便可以继续递归解析文件系统。 从目录告诉文件的最快方法是使用Perl内置的[文件测试操作][File Test Operators] 。 Perl具有可用于测试文件不同方面的运算符。 -f运算符用于标识常规文件，而不是目录或其他类型的文件。

## 使用-f File Test运算符 **(** Using the -f File Test Operator **)** ##

#!/usr/bin/perl -w
    $filename = '/path/to/your/file.doc';
    $directoryname = '/path/to/your/directory';
    if (-f $filename) {
        
    print "This is a file.";
    }
    if (-d $directoryname) {
        
    print "This is a directory.";
     }

First, you create [two strings][]: one pointing at a file and one pointing at a directory. Next, test the **$filename** with the **-f** operator, which checks to see if something is a file. This will print "This is a file." If you try the -f operator on the directory, it doesn't print. Then, do the opposite for the **$directoryname** and confirm that it is, in fact, a directory. Combine this with [a directory glob][] to sort out which elements are files and which are directories:

首先，您创建[两个字符串][two strings] ：一个指向文件，另一个指向目录。 接下来，使用**-f**运算符测试**$ filename** ，该运算符将检查是否有文件。 这将打印“这是一个文件”。 如果在目录上尝试-f运算符，则不会打印。 然后，对**$ directoryname**执行相反的操作，并确认它实际上是一个目录。 将其与[目录glob][a directory glob]结合使用， [以区分][a directory glob]哪些元素是文件，哪些是目录：

#!/usr/bin/perl -w
    @files = <*>;
    foreach $file (@files) {
        
    if (-f $file) {
        
    print "This is a file: " . $file;
    }
    if (-d $file) {
        
    print "This is a directory: " . $file;
    }
    }

A complete list of Perl [File Test Operators][File Test Operators 1] is available online.

可在线获得Perl [File Test Operators的][File Test Operators 1]完整列表。

> 翻译自: [https://www.thoughtco.com/telling-file-or-directory-perl-2641089][https_www.thoughtco.com_telling-file-or-directory-perl-2641089]

[File Test Operators]: https://www.thoughtco.com/telling-if-file-exists-in-perl-2641090
[two strings]: https://www.thoughtco.com/string-types-in-delphi-delphi-for-beginners-4092544
[a directory glob]: https://www.thoughtco.com/globbing-a-directory-2641092
[File Test Operators 1]: https://users.cs.cf.ac.uk/Dave.Marshall/PERL/node69.html#tab:fileop
[https_www.thoughtco.com_telling-file-or-directory-perl-2641089]: https://www.thoughtco.com/telling-file-or-directory-perl-2641089