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.\" ========================================================================
.\"
.IX Title "File::Fetch 3"
.TH File::Fetch 3 "2019-10-24" "perl v5.30.2" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
File::Fetch \- A generic file fetching mechanism
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& use File::Fetch;
\&
\& ### build a File::Fetch object ###
\& my $ff = File::Fetch\->new(uri => \*(Aqhttp://some.where.com/dir/a.txt\*(Aq);
\&
\& ### fetch the uri to cwd() ###
\& my $where = $ff\->fetch() or die $ff\->error;
\&
\& ### fetch the uri to /tmp ###
\& my $where = $ff\->fetch( to => \*(Aq/tmp\*(Aq );
\&
\& ### parsed bits from the uri ###
\& $ff\->uri;
\& $ff\->scheme;
\& $ff\->host;
\& $ff\->path;
\& $ff\->file;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
File::Fetch is a generic file fetching mechanism.
.PP
It allows you to fetch any file pointed to by a \f(CW\*(C`ftp\*(C'\fR, \f(CW\*(C`http\*(C'\fR,
\&\f(CW\*(C`file\*(C'\fR, \f(CW\*(C`git\*(C'\fR or \f(CW\*(C`rsync\*(C'\fR uri by a number of different means.
.PP
See the \f(CW\*(C`HOW IT WORKS\*(C'\fR section further down for details.
.SH "ACCESSORS"
.IX Header "ACCESSORS"
A \f(CW\*(C`File::Fetch\*(C'\fR object has the following accessors
.ie n .IP "$ff\->uri" 4
.el .IP "\f(CW$ff\fR\->uri" 4
.IX Item "$ff->uri"
The uri you passed to the constructor
.ie n .IP "$ff\->scheme" 4
.el .IP "\f(CW$ff\fR\->scheme" 4
.IX Item "$ff->scheme"
The scheme from the uri (like 'file', 'http', etc)
.ie n .IP "$ff\->host" 4
.el .IP "\f(CW$ff\fR\->host" 4
.IX Item "$ff->host"
The hostname in the uri. Will be empty if host was originally
\&'localhost' for a 'file://' url.
.ie n .IP "$ff\->vol" 4
.el .IP "\f(CW$ff\fR\->vol" 4
.IX Item "$ff->vol"
On operating systems with the concept of a volume the second element
of a file:// is considered to the be volume specification for the file.
Thus on Win32 this routine returns the volume, on other operating
systems this returns nothing.
.Sp
On Windows this value may be empty if the uri is to a network share, in
which case the 'share' property will be defined. Additionally, volume
specifications that use '|' as ':' will be converted on read to use ':'.
.Sp
On \s-1VMS,\s0 which has a volume concept, this field will be empty because \s-1VMS\s0
file specifications are converted to absolute \s-1UNIX\s0 format and the volume
information is transparently included.
.ie n .IP "$ff\->share" 4
.el .IP "\f(CW$ff\fR\->share" 4
.IX Item "$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.
.ie n .IP "$ff\->path" 4
.el .IP "\f(CW$ff\fR\->path" 4
.IX Item "$ff->path"
The path from the uri, will be at least a single '/'.
.ie n .IP "$ff\->file" 4
.el .IP "\f(CW$ff\fR\->file" 4
.IX Item "$ff->file"
The name of the remote file. For the local file name, the
result of \f(CW$ff\fR\->output_file will be used.
.ie n .IP "$ff\->file_default" 4
.el .IP "\f(CW$ff\fR\->file_default" 4
.IX Item "$ff->file_default"
The name of the default local file, that \f(CW$ff\fR\->output_file falls back to if
it would otherwise return no filename. For example when fetching a \s-1URI\s0 like
http://www.abc.net.au/ the contents retrieved may be from a remote file called
\&'index.html'. The default value of this attribute is literally 'file_default'.
.ie n .IP "$ff\->output_file" 4
.el .IP "\f(CW$ff\fR\->output_file" 4
.IX Item "$ff->output_file"
The name of the output file. This is the same as \f(CW$ff\fR\->file,
but any query parameters are stripped off. For example:
.Sp
.Vb 1
\& http://example.com/index.html?x=y
.Ve
.Sp
would make the output file be \f(CW\*(C`index.html\*(C'\fR rather than
\&\f(CW\*(C`index.html?x=y\*(C'\fR.
.SH "METHODS"
.IX Header "METHODS"
.ie n .SS "$ff = File::Fetch\->new( uri => 'http://some.where.com/dir/file.txt' );"
.el .SS "\f(CW$ff\fP = File::Fetch\->new( uri => 'http://some.where.com/dir/file.txt' );"
.IX Subsection "$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 \f(CW\*(C`fetch\*(C'\fRed and returns it.
.PP
Returns false on failure.
.ie n .SS "$where = $ff\->fetch( [to => /my/output/dir/ | \e$scalar] )"
.el .SS "\f(CW$where\fP = \f(CW$ff\fP\->fetch( [to => /my/output/dir/ | \e$scalar] )"
.IX Subsection "$where = $ff->fetch( [to => /my/output/dir/ | $scalar] )"
Fetches the file you requested and returns the full path to the file.
.PP
By default it writes to \f(CW\*(C`cwd()\*(C'\fR, but you can override that by specifying
the \f(CW\*(C`to\*(C'\fR argument:
.PP
.Vb 2
\& ### file fetch to /tmp, full path to the file in $where
\& $where = $ff\->fetch( to => \*(Aq/tmp\*(Aq );
\&
\& ### 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 = $ff\->fetch( to => \e$scalar );
.Ve
.PP
Returns the full path to the downloaded file on success, and false
on failure.
.ie n .SS "$ff\->error([\s-1BOOL\s0])"
.el .SS "\f(CW$ff\fP\->error([\s-1BOOL\s0])"
.IX Subsection "$ff->error([BOOL])"
Returns the last encountered error as string.
Pass it a true value to get the \f(CW\*(C`Carp::longmess()\*(C'\fR output instead.
.SH "HOW IT WORKS"
.IX Header "HOW IT WORKS"
File::Fetch is able to fetch a variety of uris, by using several
external programs and modules.
.PP
Below is a mapping of what utilities will be used in what order
for what schemes, if available:
.PP
.Vb 5
\& file => LWP, lftp, file
\& http => LWP, HTTP::Tiny, wget, curl, lftp, fetch, HTTP::Lite, lynx, iosock
\& ftp => LWP, Net::FTP, wget, curl, lftp, fetch, ncftp, ftp
\& rsync => rsync
\& git => git
.Ve
.PP
If you'd like to disable the use of one or more of these utilities
and/or modules, see the \f(CW$BLACKLIST\fR variable further down.
.PP
If a utility or module isn't available, it will be marked in a cache
(see the \f(CW$METHOD_FAIL\fR variable further down), so it will not be
tried again. The \f(CW\*(C`fetch\*(C'\fR method will only fail when all options are
exhausted, and it was not able to retrieve the file.
.PP
The \f(CW\*(C`fetch\*(C'\fR utility is available on FreeBSD. NetBSD and Dragonfly \s-1BSD\s0
may also have it from \f(CW\*(C`pkgsrc\*(C'\fR. We only check for \f(CW\*(C`fetch\*(C'\fR on those
three platforms.
.PP
\&\f(CW\*(C`iosock\*(C'\fR is a very limited IO::Socket::INET based mechanism for
retrieving \f(CW\*(C`http\*(C'\fR schemed urls. It doesn't follow redirects for instance.
.PP
\&\f(CW\*(C`git\*(C'\fR only supports \f(CW\*(C`git://\*(C'\fR style urls.
.PP
A special note about fetching files from an ftp uri:
.PP
By default, all ftp connections are done in passive mode. To change
that, see the \f(CW$FTP_PASSIVE\fR variable further down.
.PP
Furthermore, ftp uris only support anonymous connections, so no
named user/password pair can be passed along.
.PP
\&\f(CW\*(C`/bin/ftp\*(C'\fR is blacklisted by default; see the \f(CW$BLACKLIST\fR variable
further down.
.SH "GLOBAL VARIABLES"
.IX Header "GLOBAL VARIABLES"
The behaviour of File::Fetch can be altered by changing the following
global variables:
.ie n .SS "$File::Fetch::FROM_EMAIL"
.el .SS "\f(CW$File::Fetch::FROM_EMAIL\fP"
.IX Subsection "$File::Fetch::FROM_EMAIL"
This is the email address that will be sent as your anonymous ftp
password.
.PP
Default is \f(CW\*(C`File\-Fetch@example.com\*(C'\fR.
.ie n .SS "$File::Fetch::USER_AGENT"
.el .SS "\f(CW$File::Fetch::USER_AGENT\fP"
.IX Subsection "$File::Fetch::USER_AGENT"
This is the useragent as \f(CW\*(C`LWP\*(C'\fR will report it.
.PP
Default is \f(CW\*(C`File::Fetch/$VERSION\*(C'\fR.
.ie n .SS "$File::Fetch::FTP_PASSIVE"
.el .SS "\f(CW$File::Fetch::FTP_PASSIVE\fP"
.IX Subsection "$File::Fetch::FTP_PASSIVE"
This variable controls whether the environment variable \f(CW\*(C`FTP_PASSIVE\*(C'\fR
and any passive switches to commandline tools will be set to true.
.PP
Default value is 1.
.PP
Note: When \f(CW$FTP_PASSIVE\fR is true, \f(CW\*(C`ncftp\*(C'\fR will not be used to fetch
files, since passive mode can only be set interactively for this binary
.ie n .SS "$File::Fetch::TIMEOUT"
.el .SS "\f(CW$File::Fetch::TIMEOUT\fP"
.IX Subsection "$File::Fetch::TIMEOUT"
When set, controls the network timeout (counted in seconds).
.PP
Default value is 0.
.ie n .SS "$File::Fetch::WARN"
.el .SS "\f(CW$File::Fetch::WARN\fP"
.IX Subsection "$File::Fetch::WARN"
This variable controls whether errors encountered internally by
\&\f(CW\*(C`File::Fetch\*(C'\fR should be \f(CW\*(C`carp\*(C'\fR'd or not.
.PP
Set to false to silence warnings. Inspect the output of the \f(CW\*(C`error()\*(C'\fR
method manually to see what went wrong.
.PP
Defaults to \f(CW\*(C`true\*(C'\fR.
.ie n .SS "$File::Fetch::DEBUG"
.el .SS "\f(CW$File::Fetch::DEBUG\fP"
.IX Subsection "$File::Fetch::DEBUG"
This enables debugging output when calling commandline utilities to
fetch files.
This also enables \f(CW\*(C`Carp::longmess\*(C'\fR errors, instead of the regular
\&\f(CW\*(C`carp\*(C'\fR errors.
.PP
Good for tracking down why things don't work with your particular
setup.
.PP
Default is 0.
.ie n .SS "$File::Fetch::BLACKLIST"
.el .SS "\f(CW$File::Fetch::BLACKLIST\fP"
.IX Subsection "$File::Fetch::BLACKLIST"
This is an array ref holding blacklisted modules/utilities for fetching
files with.
.PP
To disallow the use of, for example, \f(CW\*(C`LWP\*(C'\fR and \f(CW\*(C`Net::FTP\*(C'\fR, you could
set \f(CW$File::Fetch::BLACKLIST\fR to:
.PP
.Vb 1
\& $File::Fetch::BLACKLIST = [qw|lwp netftp|]
.Ve
.PP
The default blacklist is [qw|ftp|], as \f(CW\*(C`/bin/ftp\*(C'\fR is rather unreliable.
.PP
See the note on \f(CW\*(C`MAPPING\*(C'\fR below.
.ie n .SS "$File::Fetch::METHOD_FAIL"
.el .SS "\f(CW$File::Fetch::METHOD_FAIL\fP"
.IX Subsection "$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).
.PP
You can reset this cache by assigning an empty hashref to it, or
individually remove keys.
.PP
See the note on \f(CW\*(C`MAPPING\*(C'\fR below.
.SH "MAPPING"
.IX Header "MAPPING"
Here's a quick mapping for the utilities/modules, and their names for
the \f(CW$BLACKLIST\fR, \f(CW$METHOD_FAIL\fR and other internal functions.
.PP
.Vb 10
\& 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
.Ve
.SH "FREQUENTLY ASKED QUESTIONS"
.IX Header "FREQUENTLY ASKED QUESTIONS"
.SS "So how do I use a proxy with File::Fetch?"
.IX Subsection "So how do I use a proxy with File::Fetch?"
\&\f(CW\*(C`File::Fetch\*(C'\fR currently only supports proxies with LWP::UserAgent.
You will need to set your environment variables accordingly. For
example, to use an ftp proxy:
.PP
.Vb 1
\& $ENV{ftp_proxy} = \*(Aqfoo.com\*(Aq;
.Ve
.PP
Refer to the LWP::UserAgent manpage for more details.
.SS "I used 'lynx' to fetch a file, but its contents is all wrong!"
.IX Subsection "I used 'lynx' to fetch a file, but its contents is all wrong!"
\&\f(CW\*(C`lynx\*(C'\fR can only fetch remote files by dumping its contents to \f(CW\*(C`STDOUT\*(C'\fR,
which we in turn capture. If that content is a 'custom' error file
(like, say, a \f(CW\*(C`404 handler\*(C'\fR), you will get that contents instead.
.PP
Sadly, \f(CW\*(C`lynx\*(C'\fR doesn't support any options to return a different exit
code on non\-\f(CW\*(C`200 OK\*(C'\fR status, giving us no way to tell the difference
between a 'successful' fetch and a custom error page.
.PP
Therefor, we recommend to only use \f(CW\*(C`lynx\*(C'\fR as a last resort. This is
why it is at the back of our list of methods to try as well.
.SS "Files I'm trying to fetch have reserved characters or non-ASCII characters in them. What do I do?"
.IX Subsection "Files I'm trying to fetch have reserved characters or non-ASCII characters in them. What do I do?"
\&\f(CW\*(C`File::Fetch\*(C'\fR is relatively smart about things. When trying to write
a file to disk, it removes the \f(CW\*(C`query parameters\*(C'\fR (see the
\&\f(CW\*(C`output_file\*(C'\fR method for details) from the file name before creating
it. In most cases this suffices.
.PP
If you have any other characters you need to escape, please install
the \f(CW\*(C`URI::Escape\*(C'\fR module from \s-1CPAN,\s0 and pre-encode your \s-1URI\s0 before
passing it to \f(CW\*(C`File::Fetch\*(C'\fR. You can read about the details of URIs
and \s-1URI\s0 encoding here:
.PP
.Vb 1
\& http://www.faqs.org/rfcs/rfc2396.html
.Ve
.SH "TODO"
.IX Header "TODO"
.ie n .IP "Implement $PREFER_BIN" 4
.el .IP "Implement \f(CW$PREFER_BIN\fR" 4
.IX Item "Implement $PREFER_BIN"
To indicate to rather use commandline tools than modules
.SH "BUG REPORTS"
.IX Header "BUG REPORTS"
Please report bugs or other issues to <bug\-file\-fetch@rt.cpan.org<gt>.
.SH "AUTHOR"
.IX Header "AUTHOR"
This module by Jos Boumans <kane@cpan.org>.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
This library is free software; you may redistribute and/or modify it
under the same terms as Perl itself.