Essential Mac OS X tools: Scroll Reverser

Scroll Reverser is a free app for Mac OS X that reverses the direction of scrolling. You can use it with OS X Tiger, Leopard and Snow Leopard to make your scrolling match the ‘natural scrolling’ in Lion.

via Scroll Reverser for Mac OS X.

I use it on Mac OS X Lion in order to use natural scrolling with the trackpad of my MacBook Air and unnatural scrolling with the attached mouse.

(kudos to @romeroabelleira for the hint) 

HP 48G: How to fix the “Warning: Invalid Card Data” problem

Recently, my good old HP 48G calculator (one of the best calculators ever built and my longtime personal favourite till today) started displaying the following message whenever I switched it on:

Warning: Invalid Card Data

Which seems a bit odd at first, considering the 48G model has no card slot (only the 48GX model has one). Luckily, there’s a simple solution: Execute the PINIT command by typing “PINIT” (without the double quotes) and pressing the ENTER key.

There’s a great, detailed explanation of this problem and the according fix in the “invalid card data at my hp48g” thread over at the independent HP calculator museum. If this warning message appears on a HP 48GX and the problem persists after applying this fix, take a look at step 3 described in the  article titled “Message, Invalid Card Data, is Displayed when the Calculator is Turned On” on HP’s support forum.

Wouldn’t it be a pity if a company with such a great history and so many great hardware products ceased to be a hardware company?

Skype 5.3.0.116 – a memory hog with memory leaks

Just take a look at the following screenshot I just took, showing two Skype 5.3.0.116 instances running on a current Windows 7 box with 4 GB of RAM:

That’s 330 MB of private memory for each instance at this very moment! Note that these numbers are steadily growing (at about 2 KB/s) for both processes – for no apparent reason. A hint, that there’s likely a memory leak somewhere in Skype.

Let’s hope Microsoft will rewrite Skype from scratch (The current code-base probably isn’t worth refactoring). I’m confident they don’t lack the human and financial resources to do it. It can only get better.

Zimbra Collaboration Server: Troubles after updating to ZCS 7.1.1 – here’s the solution.

Generally, Zimbra‘s update scripts for ZCS run smoothly. However, after updating ZCS from 7.0.1 to 7.1.1 on Ubuntu 10.04.2 LTS a couple of days ago, I noticed that most of the server’s services crashed within 1-2 hours after starting the (virtual) server.

To make a long debugging story short, here’s a summary of the problem:

The update script doesn’t properly remove old entries in /etc/rsyslog.conf when creating a new dedicated rsyslog configuration file for zimbra (/etc/rsyslog.d/60-zimbra.conf). This makes rsyslog log its own logging due to double rule entries – making /var/log/zimbra-stats.log grow at 2 MB/s. Like this, zimbra effectively DOSes itself as the server runs out of free disk space in no time (my above-average 12 GB of free space were filled within about 1 hour 40 minutes).

And here’s the solution:

1. Stop rsyslog to stop it from filling up your disk with nonsense: ‘/etc/init.d/rsyslog stop’ or ‘service rsyslog stop’
2. If necessary (i.e. if the updated server has been running for several minutes already), reclaim your free disk space by deleting/emptying big log files in /var/log, e.g. zimbra-stats.log, zimbra.log, mail.info, mail.log, mail.err, mail.warn etc.
3. Edit /etc/rsyslog.conf and remove the entries (likely at the end of the file) that look similar to these:
local0.* @mail.yourserver.com
local1.* @mail.yourserver.com
auth.* @mail.yourserver.com
local0.* -/var/log/zimbra.log
local1.* -/var/log/zimbra-stats.log
auth.* -/var/log/zimbra.log
mail.* @mail.yourserver.com
mail.* -/var/log/zimbra.log

(these are now in /etc/rsyslog.d/60-zimbra.conf)
4. Restart rsyslog: ‘service rsyslog restart’
5. Restart ZCS if it doesn’t run properly anymore: /etc/init.d/zimbra restart (you may even have to reboot the whole box if that doesn’t work)

Less is more: colordiff and more or less

In the Unix/Linux/Mac OS X world, less is more. Literally, in that ‘less‘ fully emulates ‘more‘, and figuratively, as it provides useful additional functionality like backwards scrolling. So, you really want to use ‘less’ instead of ‘more’ for paging another command’s output, e.g.

cat a_long_document.txt|less

When used to page the output of colordiff however, ‘less’ displays a mess instead of properly displaying colored output like ‘more’.
The trick is to use ‘less’ with either the -r or -R option (which both repaint the screen), i.e.

colordiff -u file_old.py file_new.py|less -r

or

colordiff -u file_old.py file_new.py|less -R

(try which one works better with your system and terminal)

Blog to be migrated to a new server

Just a quick update to let you know that this blog/changelog will soon be migrated to a new (faster) server.

I’ll keep (unavoidable, due to DNS changes [see comments below, ed.]) downtimes at the minimum and will inform you in advance about expected outages.

Thanks for your understanding.