Posts from 2013-03

Fix Time on Arch Linux Systems (Run ntpd -s every hour using systemd)

My Raspberry Pi running Arch Linux didn't get the proper time on system startup and here is the solution I came up with to solve this problem:

Create the file /etc/systemd/system/fix-time.service:

Description=Set the time using NTP time servers

ExecStart=/usr/sbin/ntpd -s


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Start a Python Tool or Web App that uses Virtualenv on system startup using Systemd

I.e. deploying a tool or Python app using systemd.

I would recommend setting up the environment variables as well as activating the virtualenv in a Bash script and call that from systemd.

Working setup

Here is the bash script starting the web app after setting up the virtualenv. It's stored in /home/coltrims/MaxiGauge/


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Start AutoSSH on System Startup Using Systemd on Arch Linux

OK, here is how to start ssh on system startup (this is the content of the systemd .service configuration file /etc/systemd/system/autossh.service):

Description=AutoSSH service for a reverse tunnel from to localhost

ExecStart=/usr/bin/autossh -M 0 -q -N -o "ServerAliveInterval 60"...

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Determining Local IPv4 and IPv6 Addresses On Mac OS X Via The Command Line

Getting IPv4 and IPv6 addresses of your local machine on Mac OS X 10.8 Mountain Lion is quite easy. Here is how it works:

IF='en0' # ← restrict to wired connection or do  IF=""  to get all
# Get local IPv4 addresses (without...

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False Color Plots

False color (or more exactly pseudo color) can be useful when a device / detector records a grayscale image and a human has to interpret it. Fine differences are hard to see in grayscale images und a false color mapping allows us to map the 255 shades of gray...

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Using ffmpeg to cut and crop a movie file

Here are the commands to issue in order to crop and/or cut a movie file with ffmpeg:

# cutting:
ffmpeg -i [input_file] -qscale 0 -ss [start_seconds] -t [duration_seconds] [output_file]
# so for example:
ffmpeg -i BSX234.avi -qscale 0 -ss <span...

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Digitus DA-70156 USB-to-Serial Adapter on Mac OS X 10.8

I downloaded the latest driver v. 2.2.18 from

After installation of the driver, the Console application in Mac OS X 10.8 shows a new log entry:

2012-10-02 2:52:55.000 PM kernel[0]: FTDIUSBSerialDriver:        0  4036001 start - ok

The System Information App...

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