File::Fetch(3p) Perl Programmers Reference Guide File::Fetch(3p)

File::Fetch(3p) Perl Programmers Reference Guide File::Fetch(3p) #

File::Fetch(3p) Perl Programmers Reference Guide File::Fetch(3p)

NNAAMMEE #

 File::Fetch - A generic file fetching mechanism

SSYYNNOOPPSSIISS #

     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;

DDEESSCCRRIIPPTTIIOONN #

 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.

AACCCCEESSSSOORRSS #

 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".

MMEETTHHOODDSS #

$$ffff == FFiillee::::FFeettcchh-->>nneeww(( uurrii ==>> ‘’hhttttpp::////ssoommee..wwhheerree..ccoomm//ddiirr//ffiillee..ttxxtt’’ ));; 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.

$$wwhheerree == $$ffff-->>ffeettcchh(( [[ttoo ==>> //mmyy//oouuttppuutt//ddiirr// || \$$ssccaallaarr]] )) 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.

$$ffff-->>eerrrroorr(([[BBOOOOLL]])) Returns the last encountered error as string. Pass it a true value to get the “Carp::longmess()” output instead.

HHOOWW IITT WWOORRKKSS #

 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::Tiny, wget, curl, lftp, fetch, HTTP::Lite, 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.

GGLLOOBBAALL VVAARRIIAABBLLEESS #

 The behaviour of File::Fetch can be altered by changing the following
 global variables:

$$FFiillee::::FFeettcchh::::FFRROOMM__EEMMAAIILL This is the email address that will be sent as your anonymous ftp password.

 Default is "File-Fetch@example.com".

$$FFiillee::::FFeettcchh::::UUSSEERR__AAGGEENNTT This is the useragent as “LWP” will report it.

 Default is "File::Fetch/$VERSION".

$$FFiillee::::FFeettcchh::::FFTTPP__PPAASSSSIIVVEE 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

$$FFiillee::::FFeettcchh::::TTIIMMEEOOUUTT When set, controls the network timeout (counted in seconds).

 Default value is 0.

$$FFiillee::::FFeettcchh::::WWAARRNN 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".

$$FFiillee::::FFeettcchh::::DDEEBBUUGG 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.

$$FFiillee::::FFeettcchh::::BBLLAACCKKLLIISSTT 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.

$$FFiillee::::FFeettcchh::::MMEETTHHOODD__FFAAIILL 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.

MMAAPPPPIINNGG #

 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

FFRREEQQUUEENNTTLLYY AASSKKEEDD QQUUEESSTTIIOONNSS #

SSoo hhooww ddoo II uussee aa pprrooxxyy wwiitthh FFiillee::::FFeettcchh?? “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.

II uusseedd ‘’llyynnxx’’ ttoo ffeettcchh aa ffiillee,, bbuutt iittss ccoonntteennttss iiss aallll wwrroonngg!! “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.

FFiilleess II’’mm ttrryyiinngg ttoo ffeettcchh hhaavvee rreesseerrvveedd cchhaarraacctteerrss oorr nnoonn--AASSCCIIII cchhaarraacctteerrss iinn tthheemm.. WWhhaatt ddoo II ddoo?? “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:

 <https://datatracker.ietf.org/doc/html/rfc2396>

TTOODDOO #

 Implement $PREFER_BIN
     To indicate to rather use commandline tools than modules

BBUUGG RREEPPOORRTTSS #

 Please report bugs or other issues to <bug-file-fetch@rt.cpan.org<gt>.

AAUUTTHHOORR #

 This module by Jos Boumans <kane@cpan.org>.

CCOOPPYYRRIIGGHHTT #

 This library is free software; you may redistribute and/or modify it
 under the same terms as Perl itself.

perl v5.36.3 2023-02-15 File::Fetch(3p)