Category: Linux

Redirect stdout and stderr to a file

il you need to run a script unattended and wish to log the output of that script you must already know that you can simply do

the problem with that is you will not log the error messages , only the output messages ,
the error are going to be displayed on the terminal but , not logged
and the error message are often as important as the output message , we do not want to dismiss them from the log ,

the solution to that issue is to run the script using this

With this , both the output will be logged in to the log file.

Orange pi zero – the battle against HEAT

As you know if you own the orange pi zero, the board run very hot. Running it without an heat sink is not really possible if your board is doing anything other than idling

and even with an heatsink you will encounter throttling if your application is a little intensive.

In an other article I managed to get a fan running controlled by the gpio’s.

A cron check every minute the cpu temperature, if it’s above a set temperature, the fan turn on.

On this photo you can see the NPN transistor fixed to the fan

 

If it’s under, the fan turns off.

The first time I did that project it was on my first orange pi zero. I made some mistakes in my wiring and, because of that, the fan only received 2.5v, it was spinning very slowly, and I was obliged to do some bash trickery to get the fan to start.

My original orangepi zero was lost during an apartment change.

I decided to order a new one and this time, I wanted to do the best work I could to integrate the fan and heatsink.

I found an acrylic case for the orange pi zero on aliexpress.

And after receiving my orange pi zero, I saw the board was a new revision, it was running even hotter than my previous orange pi zero.

Few days after receiving the board, the case arrived. It was very pretty but it was blocking any air circulation. And the heatsink had no medium to dissipate the heat since the air was hot and not circulating around the metal.
The CPU temperature rapidly ascended to 80°c.

I own several old fans disassembled from old graphics card, and one of the small fans was just the perfect size. I cut a circular hole in the top acrylic plate so the air from the fan could enter and go trough the radiator fins. The air should after exit from a void in a face of the case were optional usb port are placed.

How to use that fan?

The problem with gpio’s is that they only push very weak current and volts (3.3v). You cannot run a fan directly from a gpio.

But you can use a gpio to control an electronic switch (a transistor) that will be able to run the fan

You should use a npn transistor. They are the most common and cost next to nothing. You will find them for free when you tear down old broken power supply.

To turn on and off your switch, you just have to send 1 or 0 on it’s base.

A great way to control the gpio’s of the opi zero is with the help of that library called WiringPI

you will find instructions on how to install the library on the github page.

after installation lauch the command gpio readall

 

i chose the gpio.7 to control my fan ,

conveniently the gpio 7 is placed in the 7th place on the board , and his wPi alias is also 7

as you can see in the attached capture it’s not always the case !

 

 

 

 

 

 

i then solder my fan and transistor following this diagram :

To continue , i must write a script that check for the cpu temperature , and activate the fan if the cpu temperature is above a certain set threshold.

then , using crontab , set this script to launch every minutes.
add the line * * * * * /root/fan-control.sh to your cron jobs , using the command crontab -e

thanks to this script your fan should automatically launch when your Orange is charged , and stop when it’s return to idling.

grafana service doesn’t auto start with the system

When installing grafana and influxDB. I encountered the folowing issue

The service of grafana and influxDB where not starting .

I checked using rcconf that my service where enabled , and they where !

I then tried sysv-rc-conf and my service where correctly configured !

the services had absolutely no issue starting when called manually and started fine !


this line was telling me that the service startup was disabled !

after seaching a bit on the web ,the solution to this issue is using systemctl to enables the services.

InfluxDB insert multiples values at once using curl

If you have to insert multiples values in an influxdb database. You can use curl and insert the values one at the time.

But there is a better way like in this example

Let’s say you want to insert your tree loadaverage values in you influxdb database.

First put them into variables using these 3 lines.

Then using this curl line, insert them all at once in your influxdb database

Orange PI Zero Plus – A simple and, powerfull SBC

if you follow what’s new in the SBC world. You must know Xunglong Orange pi, they are a Chinese manufacturer known for making very cheap sbc’s based on Allwinner chip’s.

One of their most interesting sbc’s was the orange pi zero. It was small, powerful, and was ideal for a small headless server. (still available)

It was extremely cheap: less than 10€ but was plagued with some issues like very poor wifi stability, and poor software support from the manufacturer and, only 100mbps on the Ethernet port.

 

Now Xunlong has come up with an improved version of this board.

  • The wifi chip is now a well supported Realtek RTL8189FTV
  • The Ethernet port is now capable of 1Gb/s transfer rate
  • The cpu is improved with an Allwinner H5
  • The layout stay exactly the same so case are compatible.

I’ve already ordered one of these boards. At 16,02€ including shipping

It’s available at Aliexpress

OrangePI : Install OpenRTSP on a ARM device

One of my project with my OrangePI is to setup the device as a basic IP security camera server ,

the OrangePI zero , will connect to RTSP flux of the IP camera , and dump the stream on to an external disk , where it will be kept for 7 days before getting automaticly deleted
At a latter date i will run a motion detection program on these files and send a mail if motion is detected on a specific part of the frame.

after a little research , i found that a lot of people are using a program called openRTSP to record their RTSP stream to disk

But , after connecting on my OrangePi zero and trying to look for the program i found out that it’s not part of the default installation of armbian stable.

I tried to install the package using apt install openRTSP

I went to google and searched , openRTSP package ,and found out , on the debian website that openRTSP is part of the livemedia-utils package,

I went back to my SSH session and typed apt-get install livemedia-utils

There is no man pages associated with the program , you have to rely on the developer website to understand all the different options . The documentation is available here : http://www.live555.com/openRTSP/  or here if the website is down.
but as usual , in the officials repositories you only get dated version

you might want to compile the source code to have the last version available:

as root

Go to /usr/src: cd /usr/src
Get the live555 liveMedia source code: wget http://www.live555.com/liveMedia/public/live555-latest.tar.gz
Unpack it: tar -xzf live555-latest.tar.gz
Go into the  unpacked directory: cd live
Generate the make files: ./genMakefiles linux
Build the code: make
Install the latest version: make install

Bash script to clean movies name


The issue when you download movies online, is that most of the time the file name is going to be complete trash , filled with useless info like the team that made the rip or the website from where the movie was downloaded.
This is very annoying when you sort by name and the website made the idiotic decision to put their name in front of the actual film name.

for example here a typical movie name
[ Torrent9.info ] Dont.Think.Twice.2016.FRENCH.WEBRip.XviD-NEWCiNE.avi
the actual useful data that i wish to keep is Dont.Think.Twice.2016.avi

for this purpose i’ve developped a small bash script that will list all the files in a chosen directory then , if necessary , will rename the file.

this is not a very efficient script
but it’s fulfill it’s purpose and very rarely encounter a filename that he is unable to clean.

BASH:check if a number is even or odd


In a bash script you might need to check if a var is even or odd , 

in my case im going to use a if to make that check

You can use this simple code to make that check and display the result.

the result will be : 

BASH : Make a SQL query from bash

MySQL is a very convenient way to store data .
To use stored MySQL data in a BASH script you can use this simple command

this will display the result in you terminal without ASCII decorations.
if you need to use that data for something , you can store it in a var