Who is this for
This
article is for programmers who need to get file attributes under a
Windows operating System
What
you need to know
Basic
Windows commands
Basic
Perl programming
Introduction
Sometime
ago, I needed to compare two directories and compare the timestamp of
the files in these directories. This was fairly easy. However, the
difficult part was to recurse to files within subdirectories.
On a Linux/Unix machine, you can
do a stat in Perl and check for the directory bit in the file
mode item returned from stat.
But this is Windows so stat
does not return any information on whether the name is a
directory or a file. What did I do?
Option 1: The Quick Way
I
have to confess that I cheated. I did this:
|
open
(POOL, "dir $pool |") || die "Cannot open
$pool\n";
while () {
if
($pool =~ m/<DIR>/gi) { processDir() }
}
|
This is the simplest way because
it uses the DIR command in DOS and determines if the name is a
directory or not based on the string <DIR> that is
displayed by the command.
Option 2: The Cleaner Way
The cleaner way is to
use the Win32::File module. This module has two methods:
GetAttributes and SetAttributes. It also has several
constants that you can use to determine the attributes of a given
file.
The format of the
commands are:
|
GetAttributes($filename,
$resultattr);
SetAttributes($filename,
$attrtoset);
|
Each bit of the
resulting byte ($resultattr) from GetAttributes identifies an
attribute. To determine the attribute of a file, you need to check if
the bit is a 1. You can use these constants to simplify things for
you.
ARCHIVE
COMPRESSED
DIRECTORY
HIDDEN
NORMAL
OFFLINE
READONLY
SYSTEM
TEMPORARY
This is a sample routine
to show how this works:
|
#!perl
-w
use
Win32::File;
my
($pool) = @ARGV;
my
($file, $attr);
opendir
(DIR, $pool);
while
($file = readdir(DIR)) {
print
"Name: $file ";
Win32::File::GetAttributes("$pool/$file",
$attr);
if
($attr & DIRECTORY) { print "Directory " }
print
"Attr: $attr\n";
}
|
You
will need to specify the Win32::File module. We then get the
directory to be scanned from the parameter passed to the script.
We
then defined the variables to be used within the script.
Next
step is to open the directory and read all the contents of the
directory. This is done through the while ($file = readdir(DIR))
statement. Once you have the name in the directory, you can
GetAttributes it and check for the type of the file.
For
more information on Win32::File and all Win32 modules,
go to the Roth Consulting website.
|
