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Perl Cookbook by Nathan Torkington, Tom Christiansen

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Splitting a Filename into Its Component Parts

Problem

You want to extract a filename, its enclosing directory, or the extension(s) from a string that contains a full pathname.

Solution

Use routines from the standard File::Basename module.

use File::Basename;

$base = basename($path);
$dir  = dirname($path);
($base, $dir, $ext) = fileparse($path);

Discussion

The standard File::Basename module contains routines to split up a filename. dirname and basename supply the directory and filename portions respectively:

$path = '/usr/lib/libc.a';
$file = basename($path);    
$dir  = dirname($path);     

print "dir is $dir, file is $file\n";
# dir is /usr/lib, file is libc.a

The fileparse function can be used to extract the extension. To do so, pass fileparse the path to decipher and a regular expression that matches the extension. You must give fileparse this pattern because an extension isn’t necessarily dot-separated. Consider ".tar.gz"--is the extension ".tar", ".gz", or ".tar.gz"? By specifying the pattern, you control which of these you get.

$path = '/usr/lib/libc.a';
($name,$dir,$ext) = fileparse($path,'\..*');

print "dir is $dir, name is $name, extension is $ext\n";
# dir is /usr/lib/, name is libc, extension is .a

By default, these routines parse pathnames using your operating system’s normal conventions for directory separators by looking at the $^O variable, which holds a string identifying the system you’re running on. That value was determined when Perl was built and installed. You can change ...

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