NAME¶
File::Fetch - A generic file fetching mechanism
SYNOPSIS¶
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;
DESCRIPTION¶
File::Fetch is a generic file fetching mechanism.
It allows you to fetch any file pointed to by a "ftp",
"http", "file", "git" or "rsync" uri
by a number of different means.
See the "HOW IT WORKS" section further down for details.
ACCESSORS¶
A "File::Fetch" object has the following accessors
- $ff->uri
- The uri you passed to the constructor
- $ff->scheme
- The scheme from the uri (like 'file', 'http', etc)
- $ff->host
- The hostname in the uri. Will be empty if host was originally 'localhost'
for a 'file://' url.
- $ff->vol
- 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.
- $ff->share
- 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.
- $ff->path
- The path from the uri, will be at least a single '/'.
- $ff->file
- The name of the remote file. For the local file name, the result of
$ff->output_file will be used.
- $ff->file_default
- 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'.
- $ff->output_file
- 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".
METHODS¶
$ff = File::Fetch->new( uri => 'http://some.where.com/dir/file.txt' );¶
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.
$where = $ff->fetch( [to => /my/output/dir/ | \$scalar] )¶
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.
$ff->error([BOOL])¶
Returns the last encountered error as string. Pass it a true value to get the
"Carp::longmess()" output instead.
HOW IT WORKS¶
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
git => git
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.
"git" only supports "
git://" style urls.
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.
GLOBAL VARIABLES¶
The behaviour of File::Fetch can be altered by changing the following global
variables:
$File::Fetch::FROM_EMAIL¶
This is the email address that will be sent as your anonymous ftp password.
Default is "File-Fetch@example.com".
$File::Fetch::USER_AGENT¶
This is the useragent as "LWP" will report it.
Default is "File::Fetch/$VERSION".
$File::Fetch::FTP_PASSIVE¶
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
$File::Fetch::TIMEOUT¶
When set, controls the network timeout (counted in seconds).
Default value is 0.
$File::Fetch::WARN¶
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".
$File::Fetch::DEBUG¶
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.
$File::Fetch::BLACKLIST¶
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.
$File::Fetch::METHOD_FAIL¶
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.
MAPPING¶
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
FREQUENTLY ASKED QUESTIONS¶
So how do I use a proxy with File::Fetch?¶
"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.
I used 'lynx' to fetch a file, but its contents is all wrong!¶
"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.
Files I'm trying to fetch have reserved characters or non-ASCII characters in them. What do I do?¶
"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
TODO¶
- Implement $PREFER_BIN
- To indicate to rather use commandline tools than modules
BUG REPORTS¶
Please report bugs or other issues to <bug-file-fetch@rt.cpan.org<gt>.
AUTHOR¶
This module by Jos Boumans <kane@cpan.org>.
COPYRIGHT¶
This library is free software; you may redistribute and/or modify it under the
same terms as Perl itself.