And Slaters Go Plop

If you ever encounter a system lockup in Ubuntu here’s a little trick you can use to safely restart your computer.

Hold down the Alt and PrtScn/SysRq keys at the same time and, keeping them held down, enter the following sequence of keys: R, E, I, S, U, B. Hold each key down for a second or so and don’t rush.

What it does is it allow Linux to take control of your system, requests politely that all processes close, forces all processes to close, flushes data to disk, unmounts your filesystems and reboots.

Here’s a couple of mnemonics: ”Raising Elephants Is So Utterly Boring” or “Reboot Even If System Utterly Broken”.

It’s extremely rare that this is necessary due to Linux’s stability but I’ve found I’ve needed this a couple of times recently (I suspect Google Chrome is the culprit) so I’m posting this here for easy future reference from my phone.

Be default in Firefox on Linux, when you use the Google search up in the address bar it defaults to a search of google.com instead of my preferred google.co.nz. If you want to change this, go look in /usr/lib/firefox[--version--]/searchplugins/google.xml and swap out the .com for .co.nz (or whatever localised Google site you prefer).

A couple of days ago I upgraded to Ubuntu 10.04 which, in turn, upgraded my PHP version from 5.2 to 5.3. In PHP 5.3 they have completely deprecated the use of the split() function in favour of explode(). I did a quick search in my /work directory and it turns out that I have 832 files that are affected by this. All of them need to have split() replaced with explode() or the websites will throw errors every time they encounter it.

Here’s how I did it using an altered Python script I wrote a couple of years ago:

#!  /usr/bin/python
import os
import re

mydir = "/home/damian/work"

def doReplace(filePath):
	fin = open(filePath, "r")
	s = fin.read()
	fin.flush()
	fin.close()
	p = re.compile('(\s|\(|=)split\(')
	if p.search(s):
		fout = open(filePath, "w")
		s = p.sub(r'\1explode(', s)
		fout.write(s)
		fout.close()

for root, dirs, files in os.walk(mydir):
	for f in files:
		name, ext = os.path.splitext(f)
		if ext == '.php':
			doReplace(root + '/' + f)

(**UPDATE** I’ve switched the search and replace to use regular expressions because I found that ‘split()’ can be prefixed by a number of symbols but not others — i.e. don’t replace ‘preg_split()’)

Place all the images you want in the PDF into a new directory and in the console run the following from within that directory:

convert * mynewfile.pdf

The powerful convert command uses the ImageMagick library which can be installed (in Ubuntu) with the following console command:

sudo apt-get install imagemagick

In Linux, if you want to remove all .svn files and folders within a directory, navigate to the directory in your terminal and use:

find . -name ".svn" -type d -exec rm -rf {} \;

Credit

For years now I’ve used IDEs like Visual Studio and Eclipse occasionally falling back to plain text editors like GEdit or Notepad2 when making quick changes. I’ve been running Linux for almost three years now and, as you do when dealing with remote servers, have sometimes had to edit text files via the console using VIM.

VIM has been around for 18 years and is an extended version of VI which has in turn been around for 33 years. VIM = VImproved. It’s a console-based text editor designed on the assumption that you will only ever be using your keyboard (kiss your mouse goodbye) which means that much of the most common functions are based around the home keys (‘asdf’ and ‘jkl;’) and it’s packed with great programming features.

But the learning curve is about the steepest I’ve ever come across.

I decided a couple of months ago to make an effort to get to grips with it and it took a good four weeks before I was matching the programming speed I was used to with Eclipse. But now I’m finding that my speed is continuing to increase and there is no way I can go back now. It’s not the be-all-and-end-all though; if you are writing a document from scratch (like this blog entry) then VIM doesn’t really have much to offer but if you are editing an existing document (as you often are when programming) it’s streets ahead of IDEs and text editors.

One of the hardest things to get your head around is the fact that VIM is modal which means that you switch between typing stuff and doing stuff to existing text. By default you are not in ‘typing stuff’ mode and so when you type the letter w it’ll skip to the next word. If you want to add text you have to press i and then press Esc after you’ve finished to go back to ‘doing stuff’ mode. For example, to copy an entire line, paste it below, move to the new line, skip three words along, delete the remaining text on the line and start typing, in VIM you would type yy, p, 3w, c$ but the equivalent in a text editor would be to press Shift-End, Ctrl-C, End, Return, Ctrl-V, Home, Ctrl-Right, Ctrl-Right, Ctrl-Right, Shift-End, Delete and then start typing. Those key combinations may seem strange but, once you are used to them, they make a lot more sense than having to constantly move your hands away from the home keys. Especially on a laptop!

VIM is free, open source and is available for AmigaOS, Atari MiNT, BeOS, DOS, MacOS, NextStep, OS/2, OSF, RiscOS, SGI, UNIX, VMS, Windows, FreeBSD and Linux. If you are a programmer or edit plain text on a regular basis I recommend you give it a go but be aware that the curve is about as steep as curves get. If you decide to try it out I can also recommend this website to get you on your feet.

If you’re running Linux you’ll be aware that it’s crazyfast™ already. Want even more speed? Get Preload. If you’re running Ubuntu you can get it by opening your console and typing sudo apt-get install preload.

Tonight I set myself a challenge to redesign the look and feel of this blog without using any images. Lots of grey, lots of white space and all typography. And if you are viewing this on Linux it’s likely you’ll be treated to an eyeful of Deja Vu Sans+Serif Condensed – the sweetest open source font IMHO. Windows and Mac users get Helvetica, Arial and Trebuchet.

#!  /usr/bin/python2.5
import os

mydir = "/path/to/directory"
mysearch = "text to find"
myreplace = "Text to replace"

def doReplace(filePath):
    fin = open(filePath, "r")
    s = fin.read()
    fin.flush()
    fin.close()
    fout = open(filePath, "w")
    s = s.replace(mysearch, myreplace)
    fout.write(s)
    fout.close()

for root, dirs, files in os.walk(mydir):
    for f in files:
        name, ext = os.path.splitext(f)
        if ext == '.html':
            doReplace(root + '/' + f)

Explanation: This will find all files ending in .html in the directory specified in mydir along with all matching files in any subfolders and will replace the text specified in mysearch with the text in myreplace. It’s only been tested on Linux but with a bit of tweaking will run on Windows and Mac.

Ever accidentally hit ‘send’ when composing an email before you’ve attached whatever file you were intending to send? And then you have to send a quick “DOH!” follow-up email with the forgotten attachment.

I do this all the time and it makes me look like a flaming eejit.

Well, a couple of weeks ago I upgraded from Ubuntu 7.04 to 7.10 and with it came an updated version of Evolution (the Linux equivalent of Outlook). They’ve added a feature that detects if you’ve typed the word ‘attached’ but not attached any files and gives you a warning. Brilliant!