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Tie::TextDir - interface to directory of files
use Tie::TextDir;
tie %hash, 'Tie::TextDir', '/some_directory', 'rw'; # Open in read/write mode
$hash{'one'} = "some text"; # Creates file /some_directory/one
# with contents "some text"
untie %hash;
tie %hash, 'Tie::TextDir', '/etc'; # Defaults to read-only mode
print $hash{'passwd'}; # Prints contents of /etc/passwd
# Specify directory permissions explicitly
tie %hash, 'Tie::TextDir', '/some_directory', 'rw', 0775;
The Tie::TextDir module is a TIEHASH interface which lets you tie a Perl hash to a directory on the filesystem. Each entry in the hash represents a file in the directory.
To use it, tie a hash to a directory:
tie %hash, "/some_directory", 'rw'; # Open in read/write mode
If you pass 'rw' as the third parameter, you'll be in read/write mode, and any changes you make to the hash will create, modify, or delete files in the given directory. If you pass 'ro' (or nothing) as the third parameter, you'll be in read-only mode, and any changes you make to the hash won't have any effect in the given directory.
The 'rw' and 'ro' modes are actually just shorthand for
O_RDWR|O_CREAT and O_RDONLY, respectively, as defined by the
Fcntl module. You may pass Fcntl bitmasks instead of their
stringy names if you like that better. The O_RDWR flag means that
you may create or delete files in the directory, and the O_CREAT flag
means that if the directory itself doesn't exist Tie::TextDir will
create it (or die trying).
An optional fourth parameter specifies the permissions setting that
should be used when creating the tied directory. It doesn't have
any effect at this point on the permissions of the files inside the
directory, though. If the directory already exists, the permissions
setting will have no effect. The default permissions setting is
0775.
If you try to create or delete a file (by storing or deleting an entry in the tied hash) and the operation fails, a fatal error will be triggered. If you try to read a file and the operation fails, a warning message will be issued if you have Perl's warning switch turned on.
If these policies don't suit you, let me know and I can probably make the behavior configurable.
You may not use the empty string, '.', or '..' as a key in a hash,
because they would all cause integrity problems in the directory.
Other than that, Tie::TextDir won't try to check for problematic
key names, so exercise some caution (see CAUTIONS). This is to be
construed as a feature - it's possible that you might want read-only
access to an entire multi-level tree of files (though this module
would be a pretty weird way to go about it), so I don't prevent it.
If you store a key like brown/puppies and the brown/ directory
doesn't exist, Tie::TextDir won't create it for you. On most
platform this means the operation will fail.
This module has only been tested on the UNIX platform, and although it should work just fine on other platforms there may be some issues I haven't thought of.
Strange characters can cause problems when used as the keys in a hash.
For instance, if you accidentally store ../../f as a key, you'll
probably mess something up. If you knew what you were doing, you're
probably okay. I'd like to add an optional (by default on) ``safe''
mode that URL-encodes keys or something similar (I've lost the name of
the person who suggested this, but thanks!), but I haven't done it yet.
Ken Williams (ken@mathforum.org)
Copyright (c) 1998-2001 Ken Williams. All rights reserved.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
perl(1).