File::MimeInfo::Cookbook

Section: User Contributed Perl Documentation (3)
Updated: 2021-01-27
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NAME

File::MimeInfo::Cookbook - various code snippets

DESCRIPTION

Some code snippets for non-basic uses of the File::MimeInfo module:

Matching an extension

A file does not have to actually exist in order to get a mimetype for it. This means that the following will work:

  my $extension = '*.txt';
  my $mimetype = mimetype( $extension );

Mimetyping an scalar

If you want to find the mimetype of a scalar value you need magic mimetyping; after all a scalar doesn't have a filename or inode. What you need to do is to use IO::Scalar :

  use File::MimeInfo::Magic;
  use IO::Scalar;

  my $io_scalar = new IO::Scalar \$data;
  my $mimetype = mimetype( $io_scalar );

In fact most other "IO::" will work as long as they support the "seek()" and "read()" methods. Of course if you want really obscure things to happen you can always write your own IO object and feed it in there.

Be aware that when using a filehandle like this you need to set the ":utf8" binmode yourself if appropriate.

Mimetyping a filehandle

Regrettably for non-seekable filehandles like STDIN simply using an "IO::" object will not work. You will need to buffer enough of the data for a proper mimetyping. For example you could mimetype data from STDIN like this:

  use File::MimeInfo::Magic;
  use IO::Scalar;

  my $data;
  read(STDIN, $data, $File::MimeInfo::Magic::max_buffer);
  my $io_scalar = new IO::Scalar \$data;
  my $mimetype = mimetype( $io_scalar );

Be aware that when using a filehandle like this you need to set the ":utf8" binmode yourself if appropriate.

Creating a new filename

Say you have a temporary file that you want to save with a more proper filename.

  use File::MimeInfo::Magic qw#mimetype extensions#;
  use File::Copy;

  my $tmpfile = '/tmp/foo';
  my $mimetype = mimetype($tmpfile);
  my $extension = extensions($mimetype);
  my $newfile = 'untitled1';
  $newfile .= '.'.$extension if length $extension;
  move($tmpfile, $newfile);

Force the use of a certain database directory

Normally you just need to add the dir where your mime database lives to either the XDG_DATA_HOME or XDG_DATA_DIRS environment variables for it to be found. But in some rare cases you may want to by-pass this system all together. Try one of the following:

  @File::MimeInfo::DIRS = ('/home/me/share/mime');
  eval 'use File::MimeInfo';
  die if $@;

or:

  use File::MimeInfo;
  @File::MimeInfo::DIRS = ('/home/me/share/mime');
  File::MimeInfo->rehash();

This can also be used for switching between databases at run time while leaving other XDG configuration stuff alone.

AUTHOR

Jaap Karssenberg <pardus@cpan.org> Maintained by Michiel Beijen <michiel.beijen@gmail.com>

File::MimeInfo::Cookbook

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