Category Archives: Ubuntu

It’s nice to be right some times

Five short years ago I wrote an article about my desire for a Nokia N900. I was extremely enthusiastic about the device, which I saw as the future of computing and a sign of things to come. I also said:

Personally I think Linux usage overtaking Windows on personal computing devices is inevitable, and this is how it’s going to happen (although the capabilities of the N900 will have to move down to a much lower price point first). We’ll see if I’m right in 5-10 years time.

It’s now 4 years and 4 months later. I was right about Linux overtaking windows on personal computing devices, but I was wrong about how, and it happened far more quickly than I could have imagined. Continue reading

Pausing Spotify and playing a random video in Python – A party trick for Halloween

For a Halloween party last weekend I wrote a python script to pause Spotify, play a random video and start music playback again. The videos were basic ogg files I cobbled together which showed a scary image and evil laughs or screaming with OpenShot. I can’t really share them, as I don’t have rights to the media, but it’s pretty simple to recreate them yourself.

The code for this script is on Github, and I’ve reproduced the latest snapshot below. Feel free to fork and improve if you want to scare your guests, or add support for other OS’s. Presently it only supports Linux because I used dbus to perform the play/pause actions.

#!/usr/bin/python

'''
This is a Halloween party script which pauses Spotify and plays a video
at random intervals.
'''

import random
import subprocess
from subprocess import call
from time import sleep
import os
import datetime

start_time = datetime.time(21, 0, 0)
stop_time = datetime.time(23, 0, 0)

video_dir = '/home/alex/Videos/scream/'
videos = { 'scream1_nofade.ogg': 30,
'happy.ogg': 1,
'evil_laugh.ogg': 5,
}

def time_in_range(start, end, x):
"""Return true if x is in the range [start, end]"""
if start <= end:
print("start<end")
return start <= x <= end
else:
print("end<start")
return start <= x or x <= end

def weighted_choice(weights):
total = sum(weights[video] for video in weights)
r = random.uniform(0, total)
upto = 0
print("total: %s\nrandom: %s" % (total, r))

for video in weights:
w = weights[video]
if upto + w > r:
return video
upto += w
assert False, "shouldn't get here"

def spotifyPause():
command = "dbus-send --print-reply --dest=org.mpris.MediaPlayer2.spotify /org/mpris/MediaPlayer2 org.mpris.MediaPlayer2.Player.Pause"
print("pausing spotify")
os.system(command)

def spotifyPlay():
print("playing spotify")
command = "dbus-send --print-reply --dest=org.mpris.MediaPlayer2.spotify /org/mpris/MediaPlayer2 org.mpris.MediaPlayer2.Player.PlayPause"
os.system(command)

def play_video(video_file):
print("Playing %s" % video_file)
#call(['/usr/bin/mplayer', '-fs', video_file], stdout=None, stderr=None)
#result = subprocess.Popen(['/usr/bin/mplayer', '-really-quiet', '-fs', video_file])
result = subprocess.check_call(['/usr/bin/mplayer', '-really-quiet', '-fs', video_file], stdout=None, stderr=None)
return result

def playBuzz(buzzfile):
print("Buzz...")
result = subprocess.check_call(['/usr/bin/mplayer', '-really-quiet', '-ss', '18', buzzfile], stdout=None, stderr=None)
return result

def infiniteLoop():
while 1:
current_time = datetime.datetime.now().time()
#if current_time > stop_time or current_time < midday:

choice = weighted_choice(videos)

random_time = random.randrange(1200,2400)
random_time = 3

video_file = video_dir + choice
print("Chose video %s after %s seconds" % (video_file, random_time))
sleep(random_time)

# Whether to play buzz
buzz = False
if random.randrange(0,100) > 90:
buzz = True

# Continue if outside time range
if not time_in_range(start_time, stop_time, current_time):
print("Not playing video, outside time range")
continue

# Do it
spotifyPause()
if buzz:
playBuzz('/home/alex/Videos/scream/audio/buzz.mp3')
play_video(video_file)
spotifyPlay()

if __name__ == "__main__":
infiniteLoop()

Changing boot order in Ubuntu 13.04 (or Debian) – the easy way

I wanted nice, concise instructions on changing the boot order in Ubuntu 13.04, which uses Grub 2. Being a newbie focused OS however, Googling “ubuntu boot order” results in SEO blogs with lots of fluff, and then the actual instructions start out with “install package from ppa”…

What the hell, I just want to change the boot order!

Continue reading

Creating samba share in Nautilus: ‘net usershare’ returned error 255

I was having this problem on Ubuntu 12.04 (precise), but most of the Google results pointed to a bug in Hardy. However there are other causes of this problem.

In my case it was a previously-created share with a different user ID – Nautilus couldn’t create the share because there was already a share file with the same name owned by a different user.

The directory is /var/lib/samba/usershares. You should already have write access assuming you’re a member of the sambashare group (which the gui should handle for you), so all that remains to be done is remove the offending share with the same name as the one you’re trying to create.

alex@al4:~$ cd /var/lib/samba/usershares/
alex@al4:/var/lib/samba/usershares$ ls -lah
total 16K
drwxrwx--T 2 root       sambashare 4.0K Jul 25 12:33 .
drwxr-xr-x 5 root       root       4.0K May  1 10:40 ..
-rw-r--r-- 1 2046297271 2046296576  142 Oct 25  2011 music
-rw-r--r-- 1 2046297271 2046296576  128 Feb  7 17:13 videos
alex@al4:/var/lib/samba/usershares$ sudo rm music
[sudo] password for alex:
alex@al4:/var/lib/samba/usershares$ sudo rm videos
alex@al4:/var/lib/samba/usershares$

After doing the above, Nautilus was able to recreate the shares without trouble.

Intel wifi led blinking AGAIN on Ubuntu 12.04

I previously posted about this on previous versions of Ubuntu, but despite updating the instructions for 11.10 the instructions are once again obsolete. It seems Intel changes the name of its wifi kernel module every release…

On my Dell E4300 with “Intel Corporation WiFi Link 5100″ (as reported by lspci), the module name is now “iwlwifi”. This means the kernel options you add to /etc/modprobe.d should be against this module rather than iwlcore (11.04) or iwlagn (11.10).

So the instructions once again:

$ sudo -i
# echo 'options iwlwifi led_mode=1' >> /etc/modprobe.d/wlan.conf
# modprobe -r iwlwifi && modprobe iwlwifi

Bear in mind that the second line removes the wifi kernel module temporarily which will disconnect your wifi. It should automatically reconnect, if not reboot.

Slow desktop performance on Ubuntu 11.10 with nvidia graphics cards

11.10 has been a bit of a mixed bag. On the plus side it has Gnome 3, giving me a practical (and in my opinion superior) alternative to Unity. On the minus side I had upgrade glitches on both my work and personal machines, and they were unrelated issues! Might be wise to wipe and reinstall for this one (you did separate your home partition when you installed didn’t you :)).

Anyway after getting it working on my work PC (which has an 8400GS), the desktop was quite laggy in both Unity and Gnome3. It was still usable but I didn’t realise how bad it was until I went home and noticed how much smoother my laptop was, with its lowly 2009-era Intel integrated graphics…

The solution was to install the latest 285.05 Nvidia driver, but trust me when I tell you that you do not want the hassle of using the Nvidia installer from the Nvidia website.

It is much simpler to use the X Updates ppa.

So assuming you already have the default binary Nvidia driver installed and activated (nvidia-current), the quick command line solution to your performance woes should hopefully be:

sudo -i
add-apt-repository ppa:ubuntu-x-swat/x-updates
apt-get update && apt-get upgrade
reboot

You should notice an update for the nvidia-current package being installed.

That wasn’t too bad was it? :)

Stopping the Intel WiFi LED from blinking in Ubuntu

My Dell E4300 has an Intel 5100 wifi card and the led blinks constantly. I still don’t understand how Intel can consider blinking the wifi LED during data transfer to be a sensible default. For most people it blinks non-stop which is both uninformative and irritating.

Fortunately blogger Alex Cabal found a solution for Karmic, and his updated solution also works for Natty/11.04. It describes opening a text editor and pasting a couple of lines, however I’m much lazier so here’s the one-line version:

echo 'options iwlcore led_mode=1' >> /etc/modprobe.d/wlan.conf

Of course, the command above must be run as root (sudo -i), for some reason sudo gave me access denied. You also need to reboot… or you could just unload and reload the module:

modprobe -r iwlagn && modprobe iwlagn

The double ampersand just executes the next command if the previous one succeeded (exit status 0).

Update

As of Ubuntu 11.10 (kernel 3.0.0) the option has to be applied to the iwlagn module, options for iwlcore are ignored. Thus the full solution now becomes:

sudo -i
echo 'options iwlagn led_mode=1' >> /etc/modprobe.d/wlan.conf
modprobe -r iwlagn && modprobe iwlagn

Setting up a secure Ubuntu LAMP server

Disclaimer: This article is provided for your information only, and simply following this guide will not make your server “secure”. As the server administrator you are ultimately responsible for its security!

Intro

Having recently been through the process of setting up a few Ubuntu LAMP (Linux, Apache, MySQL, PHP) servers lately I thought I’d make an article out of my notes and provide a starters guide to setting up the LAMP stack on Ubuntu.

It goes without saying that the only truly secure computer is one with no network connection, no ports or input devices and is locked in a bank vault, but such a machine is not terribly useful. Regretfully, compromises must be made to allow functionality! Besides presuming insecurity, there are a lot of things you can do to make your server more secure and keep out the vast majority of would-be hackers running port scans, meta-exploit scripts and dictionary attacks.
Continue reading