Fix some errors appeared in rtorrent

After a fresh installation and configuration of rtorrent and rutorrent, below errors were appeared.

• unpack plugin: rtorrent user can't access 'unrar' program.
• rTorrent user can't access external program (sox)

To fix those, I had to install the missing programs,

In Ubuntu,

apt-get install unrar-free
apt-get install sox

Create your own OVH Server availability checker

Recently I came to know that OVH has a line of storage specific "So You Start"  (SyS) ARM based servers. I have been using a Kimsufi server, but some of these SyS servers are cheaper than the Kimsufi server I have been using. Also the storage available in SyS servers is larger than what I get from the Kimsufi Server for a slightly higher price. Therefore I decided to try a SyS ARM server (ARM-2T/1801armada01)

Unfortunately SyS ARM servers are not always available to order, specially the cheapest servers. I was refreshing their page regularly to order a server, but soon I understood that's not practical. I didn't see they become available in the web page even though I tried many times for several days.

Then I decided to automate the check so that I can order a server whenever they are available.

Fortunately OVH offers a REST API to communicate with their servers and services. It's easier to check the availability of a server sending a http request to their API. Using a bunch of commands, the availability can be checked using a one line Linux command.

Just checking the availability is not enough. There should be a way to notify the availability. I could setup a script to send the availability to an email easily, but I don't read emails often. The best way of doing that is to push a message to my mobile. I found a free service called pushme (pushme.jagcesar.se) which can be used to push a message to my mobile. It also use a REST API, so I can send a message as a http POST request to pushme servers. Then pushme forwards the message to the app installed in the mobile via iCloud.

I created a simple shell script to read the server code as an argument and used it to check the availability of that server type using the OVH REST API. If a server is available, it sends a message to pushme using pushme REST API.

Then the script was scheduled to run for every 5 minutes using a cron job so that I'll get a notification whenever a server is available.

I also created another script to send a test message in every day morning to verify that the availability checker mechanism works.

After a day of implementing this, I was able to purchase the server I wanted. :)
Hope this might help you to find a server as well.
 

Screenshot of the notifications I received about 1801armada01 availability

But note that pushme works only with Apple. you will need another message sender if you use Android. Also this is a very simple and lazy way of doing this. No errors are checked in the script and only happy path is considered.

Here are the shell scripts and crons I used,

server_checker.sh

#!/bin/bash

server_code=$1
pushmeapi_token='replace_this_with_your_pushmeapi_token'

availability_count=`curl -s "https://www.ovh.com/engine/api/dedicated/server/availabilities?country=eu&hardware=$server_code" | json_pp | grep availability | grep -v unavailable | wc -l`

if [ $availability_count -gt 0 ]; then
 curl -d "title=found a $server_code&token=$pushmeapi_token" -X POST  https://pushmeapi.jagcesar.se
fi


ping_sender.sh

#!/bin/bash

pushmeapi_token='replace_this_with_your_pushmeapi_token'

curl -d "title=test message&token=$pushmeapi_token" -X POST  https://pushmeapi.jagcesar.se


Cron Jobs

*/5 * * * * /home/seedbox/server_checker.sh 1801sk13
*/5 * * * * /home/seedbox/server_checker.sh 1801armada01
30 5 * * * /home/seedbox/ping_sender.sh

You can find out the server code from either their web page (look at the source of the web page) or using their API.

Examples:

In https://www.soyoustart.com/us/server-storage/ page, when you click ARM-2T, the server code is there at the end of the URL as 1801armada01

below command will provide the list of ARM server types,

curl -s "https://www.ovh.com/engine/api/dedicated/server/availabilities?country=eu" | json_pp | grep hardware | grep -v , | sort | uniq | grep armada

below command will provide the list of kimsufi server types,

curl -s "https://www.ovh.com/engine/api/dedicated/server/availabilities?country=eu" | json_pp | grep hardware | grep -v , | sort | uniq | grep sk



Anyway, here is a list of machine types of kimsufi servers and SyS ARM servers,

Kimsufi Servers

France
KS-1    1801sk12
KS-2    1801sk13
KS-3    1801sk14
KS-4    1801sk15
KS-5    1801sk16
KS-6    1801sk17
KS-7    1801sk18
KS-8    1801sk19
KS-9    1801sk20
KS-10    1801sk21
KS-11    1801sk22
KS-12    1801sk23

Canada
KS-1    1804sk12
KS-2    1804sk13
KS-3    1804sk14
KS-4    1804sk15
KS-5    1804sk16
KS-6    1804sk17
KS-7    1804sk18
KS-8    1804sk19
KS-9    1804sk20
KS-10    1804sk21
KS-11    1804sk22
KS-12    1804sk23

Sys ARM servers

France
ARM-2T    1801armada01
ARM-4T    1801armada02
ARM-6T    1801armada03

Canada
ARM-2T    1804armada01
ARM-4T    1804armada02
ARM-6T    1804armada03

Document viewer Evince in Fedora does not print page borders? Here is a solution!

Well, this is not a workaround or a solution available in Evince, but this is a general solution which can be used when the usual GUI applications does not have some features. 

Today I was trying to print some lecture slides using "Document Viewer" also known as "Evince" running on my Fedora laptop. I was trying to print several pages in one output page. (4 lecture slides should be printed on a single page)

Once I got the output, I realized that it does not add a border to source pages printed on a single output page. I couldn't find an option in Evince to get that done.

Fortunately I came across about the Unix/Linux lp command which uses CUPS. (Common UNIX Printing System)
Using that I was able to get what I wanted printed precisely.

Here are the steps,

1. Find out the status of the printers you have configured in the system,

lpstat -a

This will list down all the printers you have configured in your machine. Use the preferred printer as the destination of the lp command using -d option. (see the next step)

2. Use lp command to get the job done

lp -d HP-LaserJet-400 -o sides=two-sided-short-edge -o number-up=4 -o pagesize=A4 -o landscape -o page-border=single -o fit-to-page -o number-up-layout=lrtb my_document.pdf

As you can see, we can pass multiple options to lp command including the page-border which I couldn't find in Evince. You can find the explanations of each option in lp man page.

Another great option of lp is that you can send multiple files to printer.

e.g.: if you want to print all the files which have file names starting from "bla_" then you can pass bla_* to lp command so that all of them will be printed one by one.