Re^2: writing a utility to determine whether I have a working wifi connection

(re-ordered for thematic reasons) Thanks all for responses.

It might also be useful to GET your modem's status page. It can tell if your connection from your house or office to your ISP is up or not.

This simple advice came just in time for me to ask the comcast guy the address. It isn't the old 192.0.0.1 it used to be, and the page seems to have more functionality than I recall.

Another option is LWP::Online.

I'd like to unpack this a bit. First, I do have a working script:

$ ./1.lwp.pl 
execution here
execution there
$ cat 1.lwp.pl 
#!/usr/bin/perl
use 5.016;
use warnings;
use LWP::Online 'online';

say "execution here";
# "Is the internet working?"
die "NO INTARWWEB!!!" unless online();
say "execution there";
__END__
$
[download]

I attempted to dig through a few parts of this listing for Online.pm. I have any number of questions after having contended with the source for several days now. Regarding this snippet:

# Set up configuration data
use vars qw{%SUPPORTED @RELIABLE_HTTP};
BEGIN {
        # What transports do we support
        %SUPPORTED = map { $_ => 1 } qw{ http };
 
        # (Relatively) reliable websites
        @RELIABLE_HTTP = (
                # These are some initial trivial checks.
                # The regex are case-sensitive to at least
                # deal with the "couldn't get site.com case".
                'http://www.msftncsi.com/ncsi.txt' => sub { $_ eq 'Mic
+rosoft NCSI' },
                'http://google.com/'               => sub { /About Goo
+gle/         },
                'http://yahoo.com/'                => sub { /Yahoo!/  
+             },
                'http://amazon.com/'               => sub { /Amazon/ a
+nd /Cart/    },
                'http://cnn.com/'                  => sub { /CNN/     
+             },
        );
}
[download]

What is happening with the subs here?

You get about hip deep in it and need to look at source for LWP::Simple. Is this a core module?

In this snippet from LWP::Online, how does it import a lexical variable?

use LWP::Simple 5.805 qw{ get $ua };
 
use vars qw{$VERSION @ISA @EXPORT_OK};
BEGIN {
        $VERSION = '1.08';
 
        # We are an Exporter
        require Exporter;
        @ISA       = qw{ Exporter };
        @EXPORT_OK = qw{ online offline };
 
        # Set the useragent timeout
        $ua->timeout(30);
}
[download]

This is get in LWP::Simple

sub get ($)
{
    my $response = $ua->get(shift);
    return $response->decoded_content if $response->is_success;
    return undef;
}
[download]

How would one add his own site to @RELIABLE_HTTP?

Thanks for your comments

Comment on Re^2: writing a utility to determine whether I have a working wifi connection Select or Download Code

Replies are listed 'Best First'.
Re^3: writing a utility to determine whether I have a working wifi connection by Fletch (Bishop) on Jul 29, 2019 at 19:42 UTC
WRT your last question, `@RELIABLE_HTTP` is a package variable so you should be able to push (or otherwise manipulate it) after you've pulled in the module. `use LWP::Online; push @LWP::Online::RELIABLE_HTTP, q{http://groot.example.com} => sub { + /I AM GROOT/ }; ## Call http_online however . . .` [download] The cake is a lie. The cake is a lie. The cake is a lie.	[reply] [d/l] [select]
Re^3: writing a utility to determine whether I have a working wifi connection by haukex (Archbishop) on Jul 30, 2019 at 07:37 UTC
What is happening with the subs here? They are used by the code in the `sub http_online` as `$check`, where first `$_` is set to the content fetched from the URL, and then the `sub` is called, and its return value used as a boolean. Although the `sub`s you see here could be done by precompiled regexes (`qr//`), a `sub` allows for much more flexibility, a simple example being the `sub { /Amazon/ and /Cart/ }` case. LWP::Simple. Is this a core module? No, as you can find out with the corelist command: `$ corelist LWP::Simple ... LWP::Simple was not in CORE (or so I think)` [download] However, the module's distribution, libwww-perl, is quite often used by scripts, so that e.g. Strawberry Perl includes it, and it's fairly common to find it already installed alongside Perl on many NIX systems. In this snippet from LWP::Online, how does it import a lexical variable?* Just to nitpick, it's not a lexical variable, it's a package variable. They can be exported/imported just like `sub`s, e.g. Exporter supports this.	[reply] [d/l] [select]


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