Martello

Until recently I was of the opinion that, in Ireland, when the clocks change in Spring and Autumn to account for Daylight Savings Time, they always do so at 2am. Having never given it too much thought over the years, I was surprised to find out last weekend that the time they actually change differs depending on whether the clocks are going forward (Spring) or backward (Autumn).

In Ireland, the clocks go forward one hour at 1am (in Spring) but when they go back again in Autumn, they actually do so at 2am. You can confirm this for yourself on the Greenwich Meantime site for Ireland.

There is an important lesson in this too for administrators of the Unix operating system. Never schedule an import cron task between the hours of 1:00am and 2:00am because if you do, it will not run on the weekend when DST comes into effect and it may be run twice on the weekend where DST ends.

For those of you unfamiliar with how computers actually keep track of time, most computers running the Unix operating system do so based on the number of seconds that have elapsed since 1^st January 1970. Pretty much everything do with with elapsed time (internally in the operating system) is based on this date.

Now for those of you still actually reading this post, at precisely 11:31:30pm on Friday, 13^th February 2009 (i.e. tonight), this internal time representation will hit somewhat of a milestone (for 32-bit computer systems) in that the number of seconds that will have elapsed since 1^st January 1970 will be exactly 1234567890.

OK, I admit, it’s not quite the same as landing a man on the moon but worth a mention all the same I feel. One for the pub perhaps.

Source: SlashDot

I’ve encountered a number of SlashDot posts over the past week or so which discuss some of the more useful aspects of several computing tools that I use regularly. I’d commented on the first two individually (Forgotten Unix Tricks and Useful Vim Tricks) but since then, several more have emerged.

So, here are the links to each of them in one post, showing their original titles (not mine):

• (Useful) Stupid Unix Tricks
• (Useful) Stupid Vim Tricks
• (Stupid) Useful Emacs Tricks
• (Useful) Stupid Regex Tricks
• (Useful) Stupid Blackberry Tricks (slightly off the main theme though)

If someone (not me) were to make these into a book, I reckon it would prove to be quite popular. I know I’d certainly buy a copy.

I’ve been using differing flavours of Unix for almost 20 years now and have a fine appreciation for the power of the humble command-line (often from a DOS perspective too). It’s no wonder then, that I was drawn to this excellent post entitled, Stupid Unix Tricks?.

It’s a full-on geek fest of clever *nix tips and tricks and is anything but stupid (as the poorly named article suggests). If you have even the remotest passing interesting in the Unix operating system, be sure to check it out – there’s something in there for everyone.

Source: SlashDot

The Problem

Every time you check out a script file from Subversion on a Unix system, the file is missing the execute permission and you have to manually perform a chmod +x every time. This usually happens if the file was either originally added without the permission set or if it was added to Subversion from a Windows system. But more to the point, it is extremely annoying.

The Solution

The solution to this involves adding an internal Subversion property called svn:executable to the script file(s) in question. The property can either be set using Tortoise SVN from a Windows system (as described by a posting on Late Night PC found by my colleague Máté Rácz) or can be done from the command-line as follows:

$ svn propset svn:executable true myscript.sh

Both methods work and required a SVN commit afterwards.