Re: [vox-tech] Perl help requested

[Ken Herron <kherron@newsguy.coMAPSm>]

--On Tuesday, February 10, 2004 09:56:36 -0800 Richard Crawford 
<rscrawford@mossroot.com> wrote:

> I'm trying to write a Perl application that will go through a directory
> and give the amount of space used by each directory, including each
> subdirectory.  So, for example, if myDirectory1 has three files
> totalling 150K and two subdirectories (mySubDirectoryA, with 20K of
> files, and mySubDirectoryB with 50K of files), I'd like to see output
> like this:
>
> DIRECTORY         SIZE
> ======================
> myDirectory1      220K
You know, you're basically describing the "du" program. Assuming du 
doesn't meet your needs as-is, your perl script could launch du with 
appropriate arguments and massage the output as needed.

For an all-perl solution, I'd probably use File::Find to traverse the 
directory structure of interest and track total sizes using a hash table 
of directory paths. For each file you'll need two pieces of information:

1) its size, obtained by stat'ing it.
2) its pathname, which should be available through a File::Find variable. 
You'll parse this into all of the ((sub-)sub-)directories containing the 
file, in order to collate total sizes by directory.

You'll want to consider the following:

1) Are the sizes of the directories themselves part of the totals? Keep 
in mind that if the directory tree were moved to a different filesystem, 
the directories might a different amount of space.

2) What to do with hard links? If a file appears twice within the 
directory tree, does it count once or twice?

3) What to do with symlinks? The symlink itself takes up a small amount 
of space, and it refers to a file which might or might not be within the 
directory tree.

There's no one right way to handle these; it just depends on what you're 
doing with the totals.


--
"Grand Funk Railroad paved the way for Jefferson Airplane, which cleared
the way for Jefferson Starship. The stage was now set for the Alan Parsons
Project, which I believe was some sort of hovercraft." - Homer Simpson

Kenneth Herron        Kherron@newsguy.com       916-366-7338
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