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Oona Räisänen (windytan)
5,993 followers -
Signals & electronics hacker.
Signals & electronics hacker.

5,993 followers
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A mysterious file /tmp/lulz, containing the text "llulz", kept getting created every minute on my Mac.

Spent almost an hour investigating, since 'sudo crontab -e' showed an empty file. For example, I installed XFence to try and track the process creating the file, to no avail. After disabling DTrace protection from SIP I was able to use newproc.d and opensnoop to see an 'echo' command create the file. But somehow the process just kept spawning from nowhere.

Finally it turns out, rather anticlimactically, that it's a cron job created years ago - by myself:

* * * * * /bin/sh -c echo "llulz" > /tmp/lulz

It took me this long because I had only viewed the root crontab by mistake. Mystery solved, yet I have no explanation...

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Kaivopuisto Air Show

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redsea RDS decoder v0.11.0 released with improved resistance to FM noise and some bug fixes. https://github.com/windytan/redsea/releases/tag/v0.11.0

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Experimenting with ways to visualise the QRS complex in EKG over time. Here I've stacked successive waves from a single recording by triggering on the rising edge of the R wave.

Heart rate (sinus rhythm) varied quite a bit during this recording, and it can be seen that it does not affect timing during QRST.
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3/23/17
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A recommended channel for anyone who used to play with marbles as a child. Check out MarbleLympics for example. (Best if you pick a team.)

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Working LEGO Piranha Plant by JK Brickworks

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