perl File::Basename模块的使用

qder

　　在Perl中，如果想将路径和文件名，文件后缀分别提取出来，可以使用perl提供的模块File::Basename来实现。如果你在windows下安装的是activeperl，那么这个模块已经安装了，你就没必要再自己安装了，如果是使用linux系统，请到CPAN自己下载安装，安装方法看我前面写的文章。下面我就具体来说一下这个模块的使用。
File::Basename中常用的方法有fileparse, basename, dirname。fileparse方法会传回包含路经名称三个部份的串列；dirname方法传回路经位置；basename方法传回档案名称。下面我们看下面的程序来了解这个模块的工作原理。
　　
#! /usr/bin/perl
use strict;
use warnings;
use File::Basename;

my $fullname = 'C:\Users\Hunter\Documents\Perl\basename.pl';
my @suffixlist = qw(.exe .pl .txt);
my ($name,$path,$suffix) = fileparse($fullname,@suffixlist);
print "name = $name\n";
print "path = $path\n";
print "suffix = $suffix\n";
$name = fileparse($fullname,@suffixlist);
print "name = $name\n";
my $Basename = basename($fullname,@suffixlist);
print "Basename = $Basename\n";
my $dirname = dirname($fullname);
print "dirname = $dirname\n";
在上面的程序中，通过use File::Basename;来说明我们使用File::Basename这个模块。其中标量$fullname为包含文件名的路径，数组@suffixlist包含你所知道的文件后缀，这里我们只取了三个值。通过方法fileparse我们将文件路径和文件名，文件后缀分别赋值给变量$name,$path,$suffix，通过basename方法返回文件名，通过dirname方法，返回文件路径。下面我们来看一下上面程序的结果：
　　
C:\Users\Hunter\Documents\Perl>perl basename.pl
name = basename
path = C:\Users\Hunter\Documents\Perl\
suffix = .pl
name = basename
Basename = basename
dirname = C:\Users\Hunter\Documents\Perl

C:\Users\Hunter\Documents\Perl>

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File::Basename
　　文件路径可分为：位置、文件、扩展名。以c:/perl/bin/perl.exe來說，位置是指c:/perl/bin，文件名称为perl，扩展名指.exe。
预设情況下，File::Basename假设你用的是Unix型态的路径名称，但可经由呼叫fileparse_set_fstype来改变文档指定，可用的参数包括VMS, MSDOS, MacOS, AmigaOS, MSWin32。
File::Basename中常用的方法有fileparse, basename, dirname。
fileparse方法会传回包含路经名称三个部份的串列。
basename方法传回路经位置。
basename方法传回档案名称。
　　use File::Basename;  
use strict;  
fileparse_set_fstype('MSWin32');  
my $path='c:/perl/bin/perl.exe';  
my($fname, $dir, $ext)=fileparse($path, '.exe');  
print "Location: $dir/nBasename: $fname/nExtension: $ext/n";  
my($basename)=basename($path, '.exe');  
print "basename(): $basename/n";  
my($dirname)=dirname($path);  
print "dirname(): $dirname/n";  
　　输出结果：
Location: c:/perl/bin/
Basename: perl
Extension: .exe
basename(): perl
dirname(): c:/perl/bin
　　fileparse和basename的第二個参数(选择性的参数)是一般的常规表示式(regular expression)串列，它可以用来除去扩展名，让你比对某些特殊文件。
　　
　　--------------------------------------------------
　　
　　File::Basename 分割文件名数据
NAME
File::Basename - Parse file paths into directory, filename and suffix.
　　SYNOPSIS
    use File::Basename;
　　($name,$path,$suffix) = fileparse($fullname,@suffixlist);
    $name = fileparse($fullname,@suffixlist);
　　$basename = basename($fullname,@suffixlist);
    $dirname  = dirname($fullname);
DESCRIPTION
These routines allow you to parse file paths into their directory, filename and suffix.
　　NOTE: dirname() and basename() emulate the behaviours, and quirks, of the shell and C functions of the same name. See each function's documentation for details. If your concern is just parsing paths it is safer to use File::Spec's splitpath() and splitdir() methods.
　　It is guaranteed that
　　# Where $path_separator is / for Unix, \ for Windows, etc...
    dirname($path) . $path_separator . basename($path);
is equivalent to the original path for all systems but VMS.
　　fileparse
    my($filename, $directories, $suffix) = fileparse($path);
    my($filename, $directories, $suffix) = fileparse($path, @suffixes);
    my $filename                         = fileparse($path, @suffixes);
The fileparse() routine divides a file path into its $directories, $filename and (optionally) the filename $suffix.
　　$directories contains everything up to and including the last directory separator in the $path including the volume (if applicable). The remainder of the $path is the $filename.
　　# On Unix returns ("baz", "/foo/bar/", "")
     fileparse("/foo/bar/baz");
　　# On Windows returns ("baz", 'C:\foo\bar\', "")
     fileparse('C:\foo\bar\baz');
　　# On Unix returns ("", "/foo/bar/baz/", "")
     fileparse("/foo/bar/baz/");
If @suffixes are given each element is a pattern (either a string or a qr//) matched against the end of the $filename. The matching portion is removed and becomes the $suffix.
　　# On Unix returns ("baz", "/foo/bar/", ".txt")
     fileparse("/foo/bar/baz.txt", qr/\.[^.]*/);
If type is non-Unix (see "fileparse_set_fstype") then the pattern matching for suffix removal is performed case-insensitively, since those systems are not case-sensitive when opening existing files.
　　You are guaranteed that $directories . $filename . $suffix will denote the same location as the original $path.
　　basename
    my $filename = basename($path);
    my $filename = basename($path, @suffixes);
This function is provided for compatibility with the Unix shell command basename(1). It does NOT always return the file name portion of a path as you might expect. To be safe, if you want the file name portion of a path use fileparse().
　　basename() returns the last level of a filepath even if the last level is clearly directory. In effect, it is acting like pop() for paths. This differs from fileparse()'s behaviour.
　　# Both return "bar"
    basename("/foo/bar");
    basename("/foo/bar/");
@suffixes work as in fileparse() except all regex metacharacters are quoted.
　　# These two function calls are equivalent.
    my $filename = basename("/foo/bar/baz.txt",  ".txt");
    my $filename = fileparse("/foo/bar/baz.txt", qr/\Q.txt\E/);
Also note that in order to be compatible with the shell command, basename() does not strip off a suffix if it is identical to the remaining characters in the filename.
　　dirname
This function is provided for compatibility with the Unix shell command dirname(1) and has inherited some of its quirks. In spite of its name it does NOT always return the directory name as you might expect. To be safe, if you want the directory name of a path use fileparse().
　　Only on VMS (where there is no ambiguity between the file and directory portions of a path) and AmigaOS (possibly due to an implementation quirk in this module) does dirname() work like fileparse($path), returning just the $directories.
　　# On VMS and AmigaOS
    my $directories = dirname($path);
When using Unix or MSDOS syntax this emulates the dirname(1) shell function which is subtly different from how fileparse() works. It returns all but the last level of a file path even if the last level is clearly a directory. In effect, it is not returning the directory portion but simply the path one level up acting like chop() for file paths.
　　Also unlike fileparse(), dirname() does not include a trailing slash on its returned path.
　　# returns /foo/bar.  fileparse() would return /foo/bar/
    dirname("/foo/bar/baz");
　　# also returns /foo/bar despite the fact that baz is clearly a
    # directory.  fileparse() would return /foo/bar/baz/
    dirname("/foo/bar/baz/");
　　# returns '.'.  fileparse() would return 'foo/'
    dirname("foo/");
Under VMS, if there is no directory information in the $path, then the current default device and directory is used.
　　fileparse_set_fstype
  my $type = fileparse_set_fstype();
  my $previous_type = fileparse_set_fstype($type);
Normally File::Basename will assume a file path type native to your current operating system (ie. /foo/bar style on Unix, \foo\bar on Windows, etc...). With this function you can override that assumption.
　　Valid $types are "MacOS", "VMS", "AmigaOS", "OS2", "RISCOS", "MSWin32", "DOS" (also "MSDOS" for backwards bug compatibility), "Epoc" and "Unix" (all case-insensitive). If an unrecognized $type is given "Unix" will be assumed.
　　If you've selected VMS syntax, and the file specification you pass to one of these routines contains a "/", they assume you are using Unix emulation and apply the Unix syntax rules instead, for that function call only.