Posts Tagged ‘script’

Managing an iPod Shuffle (2nd gen.) in Linux

Monday, March 31st, 2014

I have an old second generation iPod Shuffle (model A1204). When I dug it out of storage it wouldn’t play any songs. I plugged it in to my mobile desktop running Debian and verified the file system could still be read. I transferred all of the existing songs off of the shuffle using Thunar and its handy renaming feature. In order to manage the tracks (i.e. add and remove songs) I needed a piece of Linux software with that capability. Unfortunately, the popular options, Banshee, Rhythmbox, and Amarok would all require that I update a significant amount of my system (mostly gnome and everything that depends on it). The best lite application I could find was gtkPod.

I first tried adding and removing tracks with gtkPod but kept getting errors. The process for adding songs was not straightforward and I couldn’t figure out how to fix those errors. Even when I got songs transferred to the device, it refused to play. It would only flash alternating green and orange indicating it couldn’t find any music. The database file wasn’t being written properly. So, gtkPod alone would not suffice (I may have an unsupported model, I couldn’t find it in the list of devices).

The solution relies on a python script “iPod shuffle database builder” which can be found on sourceforge. I used version 1.0-rc1. My process for adding tunes to the shuffle is now this (starting from scratch):

  1. Use file manager (Thunar) to permanently delete all files from the shuffle.
  2. Open gtkPod and use it to recreate the iPod Shuffle directories only.
  3. Use file manager to copy songs from desktop to Shuffle. Songs are stored in device root or under any arbitrary file hierarchy, just not in the normal /iPod_control/Music directory that iTunes uses.
  4. The python script mentioned above, named “rebuild_db.py” is copied to the root folder of the device.
  5. The python script is executed from the root folder of the device.

That’s it. Once the script rebuilds the Shuffle’s database it can be ejected and used as normal. Easy. Apple take notice.

Batch Table Operations – A QtiPlot plug-in/script

Thursday, January 30th, 2014

I’ve been taking lots of data at work. Each data file collected has to be imported to QtiPlot as a table and then several columns are added to the table and calculated from the imported data. Some days I have over 100 data sets, which means > 100 tables to manipulate. It was becoming impractical to perform all of the necessary table operations by hand. This script was written to automate the table operations I needed.

Batch Table Operations

To use one simply selects the tables to be affected from the list of existing tables. Then one selects and configures the operation to perform. Finally, clicking the “apply” button will perform the operation on the chosen tables.

As of today (1/30/14) the script allows adding and removing columns based on name, changing column types (x, y, z, etc.), and applying formulas to columns. Obviously, alot more could be done, but at the moment, this fits my needs. As I require more features I will add them. If you would like to request a feature add a comment or send me an email and I’ll see what I can do.

Download:

batchTable.zip

Edit 8/5/14:

I just tried to install this in version 0.9.8.9 of QtiPlot running on Windows 7 but was unable to get the script interface to load. The particular version of QtiPlot installed on the target machine came from an unofficial Windows binary (https://www.cells.es/old/Members/cpascual/docs/unofficial-qtiplot-packages-for-windows) that I’ve used before. That QtiPlot package comes with parts of PyQt4 but not the entire library. As such it is necessary to install both python 2.7 and PyQt4 as well. Then, the …/PyQt4/uic module folder has to be copied into the PyQt4 directory of the the QtiPlot installation.

At least, that was the solution in the past. Now this no longer works. The uic module is found but fails to load. I expect it’s because the version of Qt against which QtiPlot was complied and the version for which the uic module were written are now too different. Or it may be that the version of Python is too new (2.7.8). I got this to work in the past with Python 2.7.5. Anyway, under Windows at least, I no longer expect for the batchTable plugin to be usable because it draws its interface using the uic module I can’t get working. Things should still work on Linux installations. The long term solution would be to rewrite the plugin to use a Tkinter interface instead of Qt thereby removing the dependency problem.

Extract Y at X – A QtiPlot plug-in/script

Saturday, September 7th, 2013

I’ve written and posted a QtiPlot plug-in/script (python) I call “Extract Y at X” that extracts the y-values at a given x-value for a series of curves contained in a graph and generates a new table with those values.

The files can be downloaded using the link below. The .zip file contains three files: the script (.py) file, an xml file defining the Qt inteface (.ui), and a README file. Refer to the README file for notes on installation and use.

I wrote this script to analyze a large group of datasets that I had collected. Each dataset was measurement of current as a function of voltage for a device I had constructed and each was collected at a different temperature. In a single dataset the current grew exponentially and across datasets the current grew exponentially with temperature. In order to quantitatively determine how the current changed with temperature I needed to extract the current at some voltage from each dataset. The usual way to do this is to look through the data manually in each dataset and find the point I needed, e.g. the current at +1 V for each dataset. Given that I had so many datasets, it was useful to write a script to do this for me.

Download:

extractYatX.zip

Update 7/18/14:

I found and fixed a bug that limited the number of extracted points to 30.

Update  8/5/14:

As described in another post this plug-in may not work in Windows versions of QtiPlot without the proper dependencies satisfied. The trouble is not the script itself but its reliance on the uic module of Qt which may not have been packed with a particular QtiPlot version when it was compiled and is therefore unavailable to the script. Linux users should be fine, so long as Qt libraries are installed.

Update the DNS record for a Namecheap hosted domain automatically

Saturday, May 18th, 2013

I thought I’d share this technique I use to update the dns records for hellonull.com automatically from the web server every 5 minutes. In the event that my ISP issues me a new IP address, my site will hopefully only be down for 5 minutes.

First, you must obtain the dynamic dns (ddns) update password for your domain from Namecheap. At the time of this post, this was done by clicking the ‘Dynamic DNS’ link from the left hand menu, once your domain was already selected. When you enable dynamic DNS, a password will be generated that looks like a long string of random letters and numbers. Copy this down.

Screenshot - 05182013 - 02:59:52 PM

Next, put this password into the updateddns.sh script (below) and edit the wget commands to point to your hosts (@, www, etc.) and domain (hellonull.com). Make this script executable. It’s a good idea to make the owner of this script root and save it in a protected location, like /root because it contains ‘plain-text’ passwords. Anyone who is able to access the script is able to read the password and is therefore able to change your site’s DNS records.

#!/bin/sh
# This script updates the dynamic DNS record for several domains
# hosted on this server. It is run automatically by cron. The crontab
# file that makes this happen is stored in /etc/cron.d/ddns.
# While this script can execute as any user, it should be owned by
# root because it contains 'plain text' passwords.
# Each host (as in host.hellonull.com) must get updated individually.
# In addition, all subdomain records must be updated individually.

logFile="/var/log/updateNamecheapDDNS.log"

# this is the password as generated by namecheap
pass="You'll have to look at the original or get new ones"

# add a wget line for each host and subdomain
wget -a $logFile -O /dev/null "https://dynamicdns.park-your-domain.com/update?host=www&domain=hellonull.com&password=$pass"
wget -a $logFile -O /dev/null "https://dynamicdns.park-your-domain.com/update?host=@&domain=hellonull.com&password=$pass"
wget -a $logFile -O /dev/null "https://dynamicdns.park-your-domain.com/update?host=teachingwiki&domain=hellonull.com&password=$pass"

If you run the updateddns.sh script it should update your DNS records. To automate the process simply schedule the script using cron. I added a crontab file called ddns in /etc/cron.d which executes the script every 5 minutes.

# use this file to schedule ddns updates
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# every 5 minutes
*/5 * * * * root /root/updateddns.sh >/dev/null 2>&1