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Author image Adam Kennedy


File::Flat - Implements a flat filesystem



File::Flat implements a flat filesystem. A flat filesystem is a filesystem in which directories do not exist. It provides an abstraction over any normal filesystem which makes it appear as if directories do not exist. In effect, it will automatically create directories as needed. This is create for things like install scripts and such, as you never need to worry about the existance of directories, just write to a file, no matter where it is.

Comprehensive Implementation

The implementation of File::Flat is extremely comprehensive in scope. It has methods for all stardard file interaction taks, the -X series of tests, and some other things, such as slurp.

All methods are statically called, for example, to write some stuff to a file.

use File::Flat; File::Flat->write( 'filename', 'file contents' );

Use of other modules

File::Flat tries to use more task orientated modules wherever possible. This includes the use of File::Copy, File::NCopy, File::Remove and others. These are mostly loaded on-demand.

Non-Unix platforms

File::Flat itself should be completely capable of handling any platform through it's exclusive use of File::Spec.

However, some of the modules it relies upon, particularly File::Remove, and possible File::NCopy are not File::Spec happy yet. Results may wary on non Unix platforms. Users of non-Unix platforms are invited to patch File::Remove ( and possibly File::NCopy ) and File::Flat should work.


exists( filename )

Tests for the existance of the file. This is an exact duplicate of the -e function.

isaFile( filename )

Tests whether filename is a file. This is an exact duplicate of the -f function.

isaDirectory( filename )

Test whether filename is a directory. This is an exact duplicate of the -d function.

canRead( filename )

Does the file or directory exist, and can we read from it.

canWrite( filename )

Does the file or directory exist, and can we write to it OR can we create the file or directory.

canReadWrite( filename )

Does a file or directory exist, and can we both read and write it.

canExecute( filename )

Does a file or directory exist, and can we execute it.

canOpen( filename )

Is this something we can open a filehandle to. Returns true if filename exists, is a file, and we can read from it.

canRemove( filename )

Can we remove the file or directory.

isaText( filename )

Does the file filename exist, and is it a text file.

isaBinary( filename )

Does the file filename exist, and is it a binary file.

fileSize( filename )

If the file exists, returns it's size in bytes. Returns undef if the file does not exist.

open( filename ) OR open( mode, filename )

Rough analogue of the open function, but creates directories on demand as needed. Supports most of the normal options to the normal open function.

In the single argument form, it takes modes in the form [mode]filename. For example, all the following are valid.

  File::Flat->open( 'filename' );
  File::Flat->open( '<filename' );
  File::Flat->open( '>filename' );
  File::Flat->open( '>>filename' );
  File::Flat->open( '+<filename' );

In the two argument form, it takes the following

  File::Flat->open( '<', 'filename' );
  File::Flat->open( '>', 'filename' );
  File::Flat->open( '>>', 'filename' );
  File::Flat->open( '+<', 'filename' );

It does not support the more esoteric forms of open, such us opening to a pipe or other such things.

On successfully opening the file, it returns it as an IO::File object. Returns undef on error.

getReadHandle( filename )

The same as File::Flat->open( '<', 'filename' )

getWriteHandle( filename )

The same as File::Flat->open( '>', 'filename' )

getAppendHandle( filename )

The same as File::Flat->open( '>>', 'filename' )

getReadWriteHandle( filename )

The same as File::Flat->open( '+<', 'filename' )

read( filename )

Opens and reads in an entire file, chomping as needed.

In array context, it returns an array containing each line of the file. In scalar context, it returns a reference to an array containing each line of the file. It returns undef on error.

slurp( filename )

Slurp 'slurp's a file in. This attempt to read the entire file into a variable in as quick and memory efficient method as possible.

On success, returns a reference to a scalar, containing the entire file. Returns undef on error.

write( filename, scalar | scalar_ref | array_ref )

The write method is the main method for writing content to a file. It takes two arguments, the location to write to, and the content to write, in several forms.

If the file already exists, it will be clobered before writing starts. If the file doesn't exists, the file and any directories will be created as needed.

Content can be provided in three forms. The contents of a scalar argument will be written directly to the file. You can optionally pass a reference to the scalar. This is recommended when the file size is bigger than a few thousand characters, is it does not duplicate the file contents in memory. Alternatively, you can pass the content as a reference to an array containing the contents. To ensure uniformity, write will add a newline to each line, replacing any existing newline as needed.

Returns true on success, and undef on error.

append( filename, scalar | scalar_ref | array_ref )

This method is the same as write, except that it appends to the end of an existing file ( or creates the file as needed ).

This is the method you should be using to write to log files, etc.

overwrite( filename, scalar | scalar_ref | array_ref )

Performs an atomic write over a file. It does this by writing to a temporary file, and moving the completed file over the top of the existing file ( or creating a new file as needed ). When writing to a file that is on the same partition as /tmp, this should always be atomic.

This method otherwise acts the same as write.

copy( source, target )

The copy method attempts to copy a file or directory from the source to the target. New directories to contain the target will be created as needed.

For example File::Flat-( './this', './a/b/c/d/that' );> will create the directory structure required as needed.

In the file copy case, if the target already exists, and is a writable file, we replace the existing file, retaining file mode and owners. If the target is a directory, we do NOT copy into that directory, unlike with the 'cp' unix command. And error is instead returned.

copy will also do limited recursive copying or directories. If source is a directory, and target does not exists, a recursive copy of source will be made to target. If target already exists ( file or directory ), copy will returns with an error.

move( source, target )

The move method follows the conventions of the 'mv' command, with the exception that the directories containing target will of course be created on demand.

remove( filename )

The remove method will remove a file, or recursively remove a directory.

truncate( filename [, size ] )

The truncate method will truncate an existing file to partular size. A size of 0 ( zero ) is used if no size is provided. If the file does not exists, it will be created, and set to 0. Attempting to truncate a directory will fail.

Returns true on success, or undef on error.

makeDirectory( directory [, mode ] )

In the case where you do actually have to create a directory only, the makeDirectory method can be used to create a directory or any depth.

An optional file mode ( default 0755 ) can be provided.

Returns true on success, returns undef on error.


Contact the author


  - Needs to be made more efficient.
  - File::Spec::Object needs to be written, and File::Flat ported to use it
  - Function interface to be written, to provide importable functions.


        Adam Kennedy ( maintainer )




Copyright (c) 2002 Adam Kennedy. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.