Category Archives: Casual tech

A simple sample to print colors in Terminal with Python (local tty or stty in a ssh)

This is a very simple code, but handy.

I love the output for the simplicity and I use to check for my programs to see what will suit best.

#!/bin/env python 
# Collection of Effects
# 1m - Bold
# 2m - Normal Dark colors
# 3m - Italic
# 4m - Underline
# 7m - Background
# 9m - Strikethrough (except 38;9m)
# 40m - Bakground Dark Grey, with the colors in foreground 1 (bold),2,31-37
# 41m - Bakground Red, with the colors in foreground 1 (bold),2,30-37
# 42m - Bakground Green, with the colors in foreground 1 (bold),2,30-37
# 43m - Bakground Yellow, with the colors in foreground 1 (bold),2,30-37
# 44m - Bakground Blue, with the colors in foreground 1 (bold),2,30-37
# 45m - Bakground Violet, with the colors in foreground 1 (bold),2,30-37
# 46m - Bakground Cyan, with the colors in foreground 1 (bold),2,30-37
# 47m - Bakground Grey, with the colors in foreground 1 (bold),2,31-37
# 49m - Normal

CLEAR = "\x1B[0m"

a_s_background = ["1", "2", "3", "4", "7", "9", "40", "41", "42", "43", "44", "45", "46", "47", "49"]
a_s_color = ["1", "2", "31", "32", "33", "34", "35", "36", "37"]

for s_effect in a_s_background:
    s_line = ""
    for s_color in a_s_color:
        s_color_text = "\x1B[" + s_color + ";" + s_effect + "m"
        s_line += s_color_text + s_color + ";" + s_effect + "m" + CLEAR + " "
    print(s_line)
    print("--------------------------------------------")

You can find the source code here:

https://gitlab.com/carles.mateo/blog.carlesmateo.com-source-code/-/blob/master/colors_in_terminal.py

Please, take in count that the colors may be different depending on the Terminal used, so if you’re creating a commercial application I recommend you to try with some of them like: ubuntu terminal, ssh, putty for windows, MobaXTerm…

View from the colors from the Console of PyCharm Community Edition

I like to write Software that does not require from external packages, but if you want to use colors and write a portable program that runs in Linux, Mac OS X and Windows, I recommend you to use colorama.

A sample way to return in Python not-to-do

Today I was checking the code, the latest push to the git repo, as I always do, and I saw something that was wrong.

Often Engineers can be confused by the ways different languages treat similar operations, so similarly as POSIX I try to use an standard way to program in any language that makes the code very clear and easy to understand, no matter if it’s C, Java, Python, PHP…

My code and the code of my Teams will be clear, and easy to understand. And as the good Engineers jump from language to language upon the needs, is better for all to proceed like this to avoid confusions.

In this case I want to cover a simple case that I detected. A wrong usage.

The code was returning True on success and if not simply return.

Here I show a simple demonstration that return itself will be returning return None.

# Proof of Concept for avoiding return without the type # Author: Carles Mateo # Creation Date: 2018-03-27 #

from pprint import pprint

def boolean_test(b_value):
if b_value is False:
return

return True

b_true = boolean_test(True)
b_false = boolean_test(False)

pprint(b_true)
pprint(b_false)

if b_false is False:
print “I detect it as False (even if it’s None)”

if b_false is True:
print “I detect it as True (even if it’s None)”

if b_false is None:
print “It is None!”

print “Be careful”

Variables use the MT Notation. I include tips like this and guidelines in programming guide for my Teams.

See: Wiki Python Programming/Data Types

Using Windows 10 Appliance in Ubuntu Virtual Box 4.3.10

Microsoft has released Windows 10, and with it the possibility to Download a Windows 10 Appliance to run under Virtual Box, VMWare player, HyperV (for windows), Parallels (Mac). Their idea is to allow you to test Microsoft Edge new browser in addition of being able to test the older browsers in older VM images.

I wanted to use Windows 10 to check compatibility with my messenger c-client.

Also I wanted to know how Java behaves.

The Windows 10 VM image will work for 90 days. You can download it from here (http://dev.modern.ie/tools/vms/linux/).

Instructions are very precarious and they didn’t specify a minimum version, however if you use Virtual Box under Ubuntu 14.04, so Virtual Box 4.3.10, you’ll not be able to import the Appliance as you’ll get an error.

Update: Thanks to Razvan and Eric!, readers that reported that this also works for Mac OS 10.9.5. + Virtual Box 4.3.12 and VirtualBox 4.3.20 running under Windows 7 respectively.

‘Windows10_64’ is not a valid Guest OS type.

Result Code:	NS_ERROR_INVALID_ARG (0x80070057)
Component:	VirtualBox
Interface:	IVirtualBox {fafa4e17-1ee2-4905-a10e-fe7c18bf5554}
Callee:	IAppliance {3059cf9e-25c7-4f0b-9fa5-3c42e441670b}

I was looking to find a solution and found no solution on the Internet, so I decided to give a chance and try to fix it by myself.

The error is: ‘Windows10_64’ is not a valid Guest OS type. so obviously, the Windows10_64 is not on the list of the VirtualBox yet, it is a pretty new release. Microsoft could had shipped it with OS Type Windows 64 Other, or Windows 8 64 bits, but they did’t. I wondered if I could edit the image to trick it to appear as a recognized image.

I edited the file (MSEdge – Win10.ova) with Bless Hex Editor, an hexadecimal editor.

I looked for the String “Windows10_64” and found two occurrences.

I had to replace the string and leave it with exact number of bytes it has, so the same length (do not insert additional bytes). I searched for the list of supported OSes and found that “WindowsXP_64” would be a perfect match. I replaced that 10 for XP twice.

Then tried to import the Appliance and it worked.

I tried to run it like that, but it froze on the boot, with the new blue logo of windows.

I figured out that Windows XP would probably not be the best similar architecture, so I edited the config and I set Windows 8.1 (64 bit). I also increased the RAM to 4096 MB and set a 32 MB memory for the video card.

Then I just started the VM and everything worked.

blog-carlesmateo-com-windows10-in-virtual-box-linux

Ok, a funny note: Just started, it installed me an update without asking ;)

Raspberry Pi and osmc

There is something that fascinates me from the new Raspberry Pi, and using it as a media center.
It is the fact that is a really small board.
That is powered by a micro USB 1000 mhA.
That is powered with Linux.

I had other media centers before but they were magnetic hard disk, closed in a proprietary system.
The media center I installed, with RaspBerry Pi+, is osmc, that is Open Source Media Center.

So I have full access via ssh to the RaspBerry, and as it used so few energy I have it all the day up.
Then, as it is a Linux box, and I have full access, and I’ve around 546 MB RAM free, I can run as many background process as I want.
Do I want to be a jump point for my VPN? Let’s go.
Do I want to have some monitoring processes over few websites? Let’s do it!.

I’m really happy about having a so tiny, so few energy consuming, full Linux, being my media center and whatever I want to it to do.

I must say that is wonderful having SSH and a network interface. Ok, it’s 10/100 Mbps, not Gigabit, but it is enough to allow me to copy new files in background to the USB stick via SFTP while reproducing at FullHD Blueray MKV, files right. Also allows to mount network folders via NFS or SMB amd play from them. Copying via SFTP to the USB device is generally very slow -don’t be surprised to upload at 30 KB/s- so I recommend to set a NFS folder in the computer, with read access to the ip of the Raspberry. It’s very cool and plays totally smooth using the 100 Mbit ethernet connection. You can also configure a FTP in the Pi, that will be much faster than the SFTP.

The RaspBerry micro SD card has a performance of ~22 MB, that is enough to boot very quickly and to load programs quite fast. I have other microSD cards with Debian Jessie, and I load PHPStorm (Java based PHP IDE) quite fast.

It boots really fast, in case you stop and start it frequently.

It accepts my wired Mouse and Keyboard, and also wireless bluetooth.

I’m really in love with this small motherboard. :)

This tiny RaspBerry 2, has 4 cores at 900 Mhz.

The CPU announces (cat /proc/cpuinfo):

processor    : 3
model name    : ARMv7 Processor rev 5 (v7l)
BogoMIPS    : 38.40
Features    : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer    : 0x41
CPU architecture: 7
CPU variant    : 0x0
CPU part    : 0xc07
CPU revision    : 5

As you see, it scores only 38.40 bogomips, compared to my tower desktop 6384.59, and my old laptop 2593.45, but it’s still beautiful.

Note: you cannot trust bogomips as a performance measurement, and in addition my computers are Intel based -so CISC architecture- while RasbBerry uses ARM processors that are RISC, that is a completely different architecture. I notice a very fluid speed, only I sense a bit slowliness in the process when I install new packages. When unpacking it feels slow, although it can perfectly be caused by the SSD card IO as well, so I installed iotop and monitorized the I/O while I was installing PHP5 :) . I got small writings up to 1,000 KB/sec, so 1 MB/s, with average of ~30-50KB writing operations, no iowait, while I was seeing with htop that the core unpacking was at 100 % of CPU, the other 3 were free, so my initial conclusion is that the bottleneck was on the CPU. Still happy about my little gadget. :)

The osmc image I installed comes with python 2.7.9 and Linux kernel 3.18.9 as uname -a shows:

Linux osmc 3.18.9-5-osmc #1 SMP PREEMPT Wed Mar 11 18:59:35 UTC 2015 armv7l GNU/Linux

It also comes with wget 1.16 and curl 7.38.0.

In fact the OSMC is based on the Debian Jessie distro.

The OSMC software also have upgrades, and Debian upgrades, that keep the Linux box up to date.

So that brings a lot of possibilities.

After a sudo apt-get update I was able to install htop, mc and apache2.

sudo apt-get install htop
sudo apt-get install iotop
sudo apt-get install iftop
sudo apt-get install mc
sudo apt-get install apache2
sudo apt-get install php5
sudo apt-get instlal ncdu

So it’s a lot of fun. :)

Note: Although a 1000mhA is enough (Raspberry Pi 2 needs around 700mhA) if you plan to plug a cheap case 2.5 hard disk without external power -just USB- it will not be enough. In this case I recommend buying a 2000mhA transformer for the Pi, or a external USB hub energy powered (2000mhA otherwise you risk energy from Raspbery + USB hub being to sufficient). If the disk has external power, then you’ll have no probem. Personaly I use USB sticks.

When I had my incubator of Start ups some years ago, one of my Start up project was embedding motherboards within screens, and offering the ability to play videos, images, even flash games and animations, and manage and update everything and update contents for a groups of players from the Internet, or based on time triggers. I was finalist for selling my product to a enormous multinational, it was close, but finally a Korean company with a cheaper (and less powerful solution) won. At that time, it was 2004, motherboards were huge comparing to this tiny piece of hardware and I had to deal with different voltage, power consumption, heat dissipation, safety, etc…. so I’m really in love with this tiny piece hardware that doesn’t need even a ventilator or a big dissipation mechanism.