Find the time now at any town or city Worldwide from the command line in Gentoo Linux
September 25, 2015 2 Comments
In my hunt for a command to return the current time at any town or city in the World, I recently found a Perl script now.pl posted in 2012 by Jim Monty on grokbase. The script uses a Perl module to access the database of the GeoNames Web site. To use the module you need to have a user account at the GeoNames Web site and be connected to the Internet. The script also uses the modules URI::Escape and DateTime.
In the case of Gentoo Linux, ebuilds for some of the Perl modules used by now.pl are not available in the main Portage tree, so I installed them from a Portage local overlay, as explained below.
First I created in my local overlay an ebuild for the Perl module Geo::GeoNames and then merged it:
# mkdir -p /usr/local/portage/dev-perl/Geo-GeoNames
# cd /usr/local/portage/dev-perl/Geo-GeoNames
# nano -w Geo-GeoNames-1.01.ebuild
# ebuild Geo-GeoNames-1.01.ebuild manifest
# emerge --ask Geo-GeoNames
The ebuild Geo-GeoNames-1.01.ebuild I created is listed below:
EAPI=5
MODULE_AUTHOR=BDFOY
inherit perl-module
DESCRIPTION="Provides a perl interface to the webservices found at http://api.geonames.org"
SLOT="0"
KEYWORDS="alpha amd64 ~arm hppa ia64 ~mips ppc ppc64 ~s390 ~sh sparc x86 ~amd64-linux ~x86-linux ~ppc-macos ~x86-macos ~sparc-solaris"
IUSE=""
RDEPEND="
dev-perl/Module-Build
"
DEPEND="${RDEPEND}"
SRC_TEST=do
I’m not sure if I declared the correct dependencies in DEPEND and RDEPEND, but the Geo::GeoNames module is merged in my installation and functions correctly.
The Perl script also uses the Perl module URI::Escape, which I found out is part of the package dev-perl/URI in the Portage main tree and was already installed, so I did not need to do anything further as far as that was concerned.
Next I needed to install the Perl module Date::Time. Fortunately there is an ebuild for dev-perl/DateTime in the main Portage tree, so I merged that package directly:
# emerge --ask DateTime
Then I surfed to the GeoNames Web site and registered for a user account. My thanks go to the people who provide and maintain the site and database.
I then created a file /home/fitzcarraldo/now.pl containing the Perl script listed in Jim Monty’s post of Aug 19, 2012 on the Web page: [DateTime] Is there timezone data for any Indian cities such as Mumbai, Dehli, &c.?. My thanks also go to Jim Monty for posting his script.
My initial attempts at running now.pl resulted in an error message warning about a missing Mojo::UserAgent Perl module. I therefore needed to install the package Mojolicious but, unfortunately, the main Portage tree does not have an ebuild for it. I could have either added a third-party overlay (e.g. srcshelton) which contains a Mojolicious ebuild or downloaded the ebuild and put it in my local overlay. I opted for the latter, and merged it:
# mkdir -p /usr/local/portage/dev-perl/Mojolicious
# cd /usr/local/portage/dev-perl/Mojolicious
# cp /home/fitzcarraldo/Downloads/Mojolicious-5.30.ebuild .
# ebuild Mojolicious-5.30.ebuild manifest
# emerge --ask Mojolicious
Update July 24, 2017: the package Mojolicious is now in the Portage main tree, so you can now merge that instead of adding it to a local overlay.
Despite the examples given in Jim Monty’s post using now.pl with place names containing diacritics, in my case the script could not handle them, so I made a couple of small modifications, and the script I’m using is show below:
#!perl
use strict;
use warnings;
use DateTime;
use Geo::GeoNames;
use URI::Escape;
use Encode;
binmode STDOUT, ':encoding(UTF-8)';
my $city = decode("UTF-8", @ARGV ? shift : 'London');
my $geo = Geo::GeoNames->new( username => '***********' );
# N.B. Replace the asterisks with your GeoNames user name.
my $result = $geo->search(
q => uri_escape_utf8($city),
maxRows => 1,
style => 'FULL'
);
defined $result->[0] or die "Unrecognized city '$city'\n";
my $city_name = $result->[0]->{name};
my $country_name = $result->[0]->{countryName};
my $time_zone = $result->[0]->{timezone}{content};
my $time_now = DateTime->now( time_zone => $time_zone );
print "$city_name ($country_name) $time_now ($time_zone)\n";
exit 0;
I made the script executable and ensured my user account could use it:
# chmod +x /home/fitzcarraldo/now.pl
# chown fitzcarraldo:fitzcarraldo /home/fitzcarraldo/now.pl
Now if I enter the name of a town or city anywhere in the World while my laptop is connected to the Internet, the script prints the town/city name, country, local time and the time zone’s name as given in the zoneinfo database (a.k.a. ‘Olsen database’, ‘tz database‘ and ‘IANA time zone database’):
$ cd
$ perl now.pl
London (United Kingdom) 2015-09-25T23:10:16 (Europe/London)
$ perl now.pl "London Canada"
London (Canada) 2015-09-25T18:10:22 (America/Toronto)
$ perl now.pl Paris
Paris (France) 2015-09-26T00:10:29 (Europe/Paris)
$ perl now.pl "New York"
New York (United States) 2015-09-25T18:10:41 (America/New_York)
$ perl now.pl Tokyo
Tokyo (Japan) 2015-09-26T07:10:50 (Asia/Tokyo)
$ perl now.pl "Mexico City"
Mexico City (Mexico) 2015-09-25T17:10:59 (America/Mexico_City)
$ perl now.pl "Kuala Lumpur"
Kuala Lumpur (Malaysia) 2015-09-26T06:11:09 (Asia/Kuala_Lumpur)
$ perl now.pl "São Paulo"
São Paulo (Brazil) 2015-09-25T19:11:29 (America/Sao_Paulo)
$ perl now.pl Maceio
Maceió (Brazil) 2015-09-25T19:11:39 (America/Maceio)
$ perl now.pl Maceió
Maceió (Brazil) 2015-09-25T19:11:48 (America/Maceio)
$ perl now.pl "Várzea Grande"
Várzea Grande (Brazil) 2015-09-25T18:12:04 (America/Cuiaba)
$ perl now.pl "Mos Eisley"
Unrecognized city 'Mos Eisley'
now.pl works by first using the Geo::GeoNames module to look up in the GeoNames database via the Internet the time zone for the town/city you have specified, then using the Date::Time module to look up the time in that time zone from the zoneinfo data in your installation, based on the time now in your installation’s system clock. In other words, if your system clock is, for example, 3 minutes ahead of actual time then the time returned by now.pl for the relevant time zone would also be 3 minutes fast. But if your system clock is correct, the script would return an accurate time for the requested town/city.
My interest in finding a command that returns the current time at any town or city around the Globe was because I wanted to create a keyboard shortcut to insert a signature in my e-mails, displaying my current location and the local time wherever I happened to be (I have to travel internationally frequently because of my work). In my next post I will explain how I created such an e-mail signature.
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