After doing patch-Tuesday update yesterday, my Windows 7 no longer booted. This is the second time it happened. Last time I fixed it, didn’t get to document and it took me a while to figure out how I did it. This version of Windows is Windows 7 Professional 32-bit. After some digging, MpFilter.sys is Microsoft Malware Protection Minifilter, which is a part of Microsoft Security Essentials (MSE). MSE is installed on my Windows 7 machine. ...

In the past few weeks, I noticed that data transmitting from one of sensor nodes got dropped dramatically. This sensor node is an Arduino Micro using nRF24L01+ as the transmitter. Well, it’s supposed to send data to the base station once every 30 seconds; however the transmitting recurrence time exceeded 2 minutes. By default the transmitting rate is at 1 Mb/s, so I dropped it to 250 Kb/s to see if had any better improvement. It didn’t help. ...

There must already exist a gazillion articles about how to do this; but one more won’t hurt, right? Suppose you have a list, called alist, as the following: In [2]: alist Out[2]: ['apple', 'banana', 'pear'] To create a string from “alist” with a comma separator, we can do this: In [3]: ','.join(alist) Out[3]: 'apple,banana,pear' Basically, you can place a desired separator in the ',' or omit it totally. Reference: http://www.decalage.info/en/python/print_list

While looking at the log file on my Raspberry Pi (running Fedora 20 Remix), I noticed that the date/time didn’t look right. EDT is a North American Eastern Daylight Time, which is 4 hours behind UTC. You can read more about it here. In my case, I prefer the time zone set to AEST (Australian Eastern Standard Time), which is 10 hour ahead of UTC. ...

This is just a quick note to remind myself how to enable or disable services using Systemd. In this example, I’m using denyhosts service. Check if a service is running. # systemctl status denyhosts denyhosts.service - SSH log watcher Loaded: loaded (/usr/lib/systemd/system/denyhosts.service; disabled) Active: inactive (dead) Start a service and verify its running status: # systemctl start denyhosts # systemctl status denyhosts denyhosts.service - SSH log watcher Loaded: loaded (/usr/lib/systemd/system/denyhosts.service; disabled) Active: active (running) since Thu 2014-07-17 01:44:29 EDT; 1min 25s ago Process: 15722 ExecStart=/usr/bin/denyhosts.py --daemon --config=/etc/denyhosts.conf (code=exited, status=0/SUCCESS) Process: 15719 ExecStartPre=/bin/rm -f /run/lock/subsys/denyhosts (code=exited, status=0/SUCCESS) Main PID: 19367 (denyhosts.py) CGroup: /system.slice/denyhosts.service └─19367 /usr/bin/python /usr/bin/denyhosts.py --daemon --config=/etc/denyhosts.conf Jul 17 01:44:29 pidora.local systemd[1]: PID file /run/lock/subsys/denyhosts not readable (yet?) after start. Jul 17 01:44:29 pidora.local systemd[1]: Started SSH log watcher. Check if a denyhosts service is enabled or not: ...