File::Fetch - A generic file fetching mechanism
- use File::Fetch;
- ### build a File::Fetch object ###
- my $ff = File::Fetch->new(uri => 'http://some.where.com/dir/a.txt');
- ### fetch the uri to cwd() ###
- my $where = $ff->fetch() or die $ff->error;
- ### fetch the uri to /tmp ###
- my $where = $ff->fetch( to => '/tmp' );
- ### parsed bits from the uri ###
- $ff->uri;
- $ff->scheme;
- $ff->host;
- $ff->path;
- $ff->file;
File::Fetch is a generic file fetching mechanism.
It allows you to fetch any file pointed to by a ftp
, http
,
file
, or rsync
uri by a number of different means.
See the HOW IT WORKS
section further down for details.
A File::Fetch
object has the following accessors
The uri you passed to the constructor
The scheme from the uri (like 'file', 'http', etc)
The hostname in the uri. Will be empty if host was originally 'localhost' for a 'file://' url.
On operating systems with the concept of a volume the second element of a file:// is considered to the be volume specification for the file. Thus on Win32 this routine returns the volume, on other operating systems this returns nothing.
On Windows this value may be empty if the uri is to a network share, in which case the 'share' property will be defined. Additionally, volume specifications that use '|' as ':' will be converted on read to use ':'.
On VMS, which has a volume concept, this field will be empty because VMS file specifications are converted to absolute UNIX format and the volume information is transparently included.
On systems with the concept of a network share (currently only Windows) returns the sharename from a file://// url. On other operating systems returns empty.
The path from the uri, will be at least a single '/'.
The name of the remote file. For the local file name, the result of $ff->output_file will be used.
The name of the default local file, that $ff->output_file falls back to if it would otherwise return no filename. For example when fetching a URI like http://www.abc.net.au/ the contents retrieved may be from a remote file called 'index.html'. The default value of this attribute is literally 'file_default'.
The name of the output file. This is the same as $ff->file, but any query parameters are stripped off. For example:
- http://example.com/index.html?x=y
would make the output file be index.html rather than
index.html?x=y.
Parses the uri and creates a corresponding File::Fetch::Item object,
that is ready to be fetch
ed and returns it.
Returns false on failure.
Fetches the file you requested and returns the full path to the file.
By default it writes to cwd()
, but you can override that by specifying
the to
argument:
- ### file fetch to /tmp, full path to the file in $where
- $where = $ff->fetch( to => '/tmp' );
- ### file slurped into $scalar, full path to the file in $where
- ### file is downloaded to a temp directory and cleaned up at exit time
- $where = $ff->fetch( to => \$scalar );
Returns the full path to the downloaded file on success, and false on failure.
Returns the last encountered error as string.
Pass it a true value to get the Carp::longmess()
output instead.
File::Fetch is able to fetch a variety of uris, by using several external programs and modules.
Below is a mapping of what utilities will be used in what order for what schemes, if available:
- file => LWP, lftp, file
- http => LWP, HTTP::Lite, wget, curl, lftp, fetch, lynx, iosock
- ftp => LWP, Net::FTP, wget, curl, lftp, fetch, ncftp, ftp
- rsync => rsync
If you'd like to disable the use of one or more of these utilities
and/or modules, see the $BLACKLIST
variable further down.
If a utility or module isn't available, it will be marked in a cache
(see the $METHOD_FAIL
variable further down), so it will not be
tried again. The fetch
method will only fail when all options are
exhausted, and it was not able to retrieve the file.
The fetch
utility is available on FreeBSD. NetBSD and Dragonfly BSD
may also have it from pkgsrc
. We only check for fetch
on those
three platforms.
iosock
is a very limited IO::Socket::INET based mechanism for
retrieving http
schemed urls. It doesn't follow redirects for instance.
A special note about fetching files from an ftp uri:
By default, all ftp connections are done in passive mode. To change
that, see the $FTP_PASSIVE
variable further down.
Furthermore, ftp uris only support anonymous connections, so no named user/password pair can be passed along.
/bin/ftp is blacklisted by default; see the $BLACKLIST
variable
further down.
The behaviour of File::Fetch can be altered by changing the following global variables:
This is the email address that will be sent as your anonymous ftp password.
Default is File-Fetch@example.com
.
This is the useragent as LWP
will report it.
Default is File::Fetch/$VERSION
.
This variable controls whether the environment variable FTP_PASSIVE
and any passive switches to commandline tools will be set to true.
Default value is 1.
Note: When $FTP_PASSIVE is true, ncftp
will not be used to fetch
files, since passive mode can only be set interactively for this binary
When set, controls the network timeout (counted in seconds).
Default value is 0.
This variable controls whether errors encountered internally by
File::Fetch
should be carp
'd or not.
Set to false to silence warnings. Inspect the output of the error()
method manually to see what went wrong.
Defaults to true
.
This enables debugging output when calling commandline utilities to
fetch files.
This also enables Carp::longmess
errors, instead of the regular
carp
errors.
Good for tracking down why things don't work with your particular setup.
Default is 0.
This is an array ref holding blacklisted modules/utilities for fetching files with.
To disallow the use of, for example, LWP
and Net::FTP
, you could
set $File::Fetch::BLACKLIST to:
- $File::Fetch::BLACKLIST = [qw|lwp netftp|]
The default blacklist is [qw|ftp|], as /bin/ftp is rather unreliable.
See the note on MAPPING
below.
This is a hashref registering what modules/utilities were known to fail for fetching files (mostly because they weren't installed).
You can reset this cache by assigning an empty hashref to it, or individually remove keys.
See the note on MAPPING
below.
Here's a quick mapping for the utilities/modules, and their names for the $BLACKLIST, $METHOD_FAIL and other internal functions.
- LWP => lwp
- HTTP::Lite => httplite
- HTTP::Tiny => httptiny
- Net::FTP => netftp
- wget => wget
- lynx => lynx
- ncftp => ncftp
- ftp => ftp
- curl => curl
- rsync => rsync
- lftp => lftp
- fetch => fetch
- IO::Socket => iosock
File::Fetch
currently only supports proxies with LWP::UserAgent.
You will need to set your environment variables accordingly. For
example, to use an ftp proxy:
- $ENV{ftp_proxy} = 'foo.com';
Refer to the LWP::UserAgent manpage for more details.
lynx
can only fetch remote files by dumping its contents to STDOUT
,
which we in turn capture. If that content is a 'custom' error file
(like, say, a 404 handler), you will get that contents instead.
Sadly, lynx
doesn't support any options to return a different exit
code on non-200 OK status, giving us no way to tell the difference
between a 'successful' fetch and a custom error page.
Therefor, we recommend to only use lynx
as a last resort. This is
why it is at the back of our list of methods to try as well.
File::Fetch
is relatively smart about things. When trying to write
a file to disk, it removes the query parameters
(see the
output_file
method for details) from the file name before creating
it. In most cases this suffices.
If you have any other characters you need to escape, please install
the URI::Escape
module from CPAN, and pre-encode your URI before
passing it to File::Fetch
. You can read about the details of URIs
and URI encoding here:
- http://www.faqs.org/rfcs/rfc2396.html
Please report bugs or other issues to <bug-file-fetch@rt.cpan.org<gt>.
This module by Jos Boumans <kane@cpan.org>.
This library is free software; you may redistribute and/or modify it under the same terms as Perl itself.