Command Line HowTo Linux Ubuntu

ERROR: Failed to build gem native extension.

While attempting to install a package from gem, I encountered this issue:

sudo gem install dashing
Building native extensions.  This could take a while...
ERROR:  Error installing dashing:
	ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.9.1 extconf.rb
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- mkmf (LoadError)
	from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
	from extconf.rb:2:in `
' Gem files will remain installed in /var/lib/gems/1.9.1/gems/eventmachine-1.2.3 for inspection. Results logged to /var/lib/gems/1.9.1/gems/eventmachine-1.2.3/ext/gem_make.out

Simply to solve this you just need to install ruby-dev packages on ubuntu:

sudo apt-get install ruby-dev
Command Line Linux Ubuntu

apt-get error “E: Unable to correct problems, you have held broken packages.”

The problem you have encountered is basically the package, or dependencies that are conflicting or broken and are therefore “held”.

You can check what (if any) packages are held using the following command:

dpkg --get-selections | grep hold


apt-mark showhold

If there’s no packages, or no output. That means it’s probably a dependency issue which apt-get isn’t able to resolve. apt-get is actually pretty bad at dealing with the dependencies and it’s often easier to try install via aptitude (an alternative to apt-get, which is widely regarded as a better solution to the default apt-get.


First install aptitude:

sudo apt-get install aptitude

and then install the package:

sudo aptitude install [package_name]
Linux Ubuntu Uncategorized

Linux Mint: “Could not download all repository indexes”

When running

sudo apt-get update

or attempting to update via the Update Manager in Linux Mint (13), I was fronted with the following error:

Failed to fetch ... tion-en_US Unable to connect to
Failed to fetch ... slation-en Unable to connect to
Failed to fetch ... tion-en_US Unable to connect to
Failed to fetch ... slation-en Unable to connect to
Failed to fetch ... tion-en_US Unable to connect to
Failed to fetch ... slation-en Unable to connect to
Some index files failed to download. They have been ignored, or old ones used instead.

This is caused by missing repositories which are either old, broken or currently down. In order to fix it, simply run:

sudo apt-get update fix-missing

If this option doesn’t work, try changing the repository mirrors with the following guide.

HowTo Linux Raspberry Pi Ubuntu

Unknown encoder ‘libx264’

If you encounter a problem similar to the following, where you’re missing the libx264 codec try this solution.

avconv -r 10 -i image%06d.jpg -r 10 -vcodec libx264 -crf 20 -g 15 timelapse1.mp4

avconv version 0.8.6-6:0.8.6-0ubuntu0.12.10.1, Copyright (c) 2000-2013 the Libav developers
built on Apr 2 2013 17:02:16 with gcc 4.7.2
Input #0, image2, from 'image%06d.jpg':
Duration: 00:02:21.20, start: 0.000000, bitrate: N/A
Stream #0.0: Video: mjpeg, yuvj420p, 2592x1944, 10 fps, 10 tbr, 10 tbn, 10 tbc
Unknown encoder 'libx264'

In order to acquire libx264, on Debian based distros (Ubuntu, Mint, Raspbian) install the following package:

 sudo apt-get install libavcodec-extra-53
Linux Ubuntu

VirtualBox (4.26) USB Issue: “unable to enumerate USB device on port n”

After a couple of hours trying to get a USB device (USB-to-Serial FTDI) working in VirtualBox with OSX host and Ubuntu 12.10 guest and receiving an error message similar to the follow:

usb 6-3: new full speed USB device number 24 using ohci_hcd
usb 6-3: device not accepting address 24, error -110
hub 6-0:1.0: unable to enumerate USB device on port 2

It turns out, the issue lies with VirtualBox, when the machine is given more than 1 processor it fails to properly mount any USB device. The only fix I have found to work is to simply reduce the number of processors back to 1. Once it’s returned the USB devices work simply by mounting them the usual way, from the VirtualBox menu > Devices > USB Devices >.

If anyone find a better solution, be sure to comment below.

Command Line HowTo Linux Ubuntu

what(): Serial Port failed to open: open: Permission denied

what():  Serial Port failed to open: open: Permission denied

Trying to get access to your serial port without the need for running whatever program as sudo or root? You’re probably not in the dialout group, if that’s the case, here’s the fix:

First, check you aren’t in the group:

groups alex

This will list all the groups the user is in, here the user is called ‘alex’, just substitute that for your own username. If the output doesn’t contain the dialout group, keep going. If it does, you might have another issue which this isn’t likely to solve.

sudo gpasswd --add alex dialout

This command will add the user ‘alex’ to the ‘dialout’ group. Once that’s done you’ll need to logout and back in again for the effects to take place.

Fedora HowTo Linux Ubuntu

Team Fortress 2 Segmentation Fault – Steam for Linux

After getting invited to join the Steam Beta for Linux, (after weeks of using the bypass) I decided to get playing some TF2. After the long install and download I booted it up. The Value splash screen with the tap-guy loads and the menu begins to load, but once it has finished, the game closed and returned to my desktop.

So I tried again, but this time ran steam through terminal in order to get some error messages. The following is what I found to occur when the game crashed:

response: CrashID=bp-ca59d62f-9c2b-47e4-8cd9-9d0b02121212
/home/alex/Steam/SteamApps/username/Team Fortress 2/ line 72: 4811 Segmentation fault ${GAME_DEBUGGER} "${GAMEROOT}"/${GAMEEXE} "$@"
Game removed: AppID 440 "Team Fortress 2", ProcID 4811
saving roaming config store to 'sharedconfig.vdf'
roaming config store 2 saved successfully

To fix it, there’s a pretty simple solution. This is to add the option “-nojoy” to the launch options of the game:

  1. Right click Team Fortress 2 in the Library pane of Steam.
  2. Click “Properties”.
  3. Click “Set Launch Options”
  4. Add the following: -nojoy
  5. Hit OK and launch the game, everything should be working!

If you’re running Fedora, some folk have found another solution to this fix, if the previous doesn’t work:

sudo setsebool -P allow_execheap 1

Where it seems SELinux isn’t allowing the game to start for whatever reasons.


Arch Linux Command Line Linux Raspberry Pi Ubuntu

Setting up a static external IP address on a Raspberry Pi (For Free!)

If you’re planning on setting up your raspberry pi as a server or a project that’ll want you to access it from a static external IP address, here’s a really simple and quick way to get that up and running for free.

First off, this guide uses the free service from no-ip (, so you’ll want to head over there and register for that. (

Done? Ok, great. Next you’ll want to create a new host, this can be found under the “Hosts/Redirects” page (this link should work if you’re logged in:

Click “Add a Host”

Enter a name and choose one of the free domains from the drop down box (alternatively you are able to use an existing domain name or sub-domain if you have one.) There are some other settings, if you know what you’re doing go ahead and choose which you prefer but from those who just want to get this set up you can now click “Create Host” and you’re done.

Now, in order for this system to know what your pi’s current address is in order to assign it that domain address you need to install the client on the pi (thankfully, they have a Linux one!).

Download the latest version of their client –

tar -zxvf noip-duc-linux.tar.gz
sudo make install

One there, you’ll be promted for your email and password for
It will then show you have a host registered, just hit enter.
Then it will ask to update the host you made on the site “Do you wish to have host [] updated?[N] (y/N)”. Type “Y” then hit enter.
It’ll ask for an update interval, this can be left at 30.
Then it’ll ask if you want to “run something on successful update”, basically this allows a script to run if it gets a connection. Choose N and hit return.

That’s it, you should be done. Just test out the connection via SSH or ping and compare the IPs.

Command Line HowTo Linux Ubuntu

HowTo: Restore Your Default .bashrc File in Ubuntu

If you’ve managed to find yourself deleting, overwriting or generally messing up your profiles .bashrc file there’s a really easy way to fix it. A default version of the file can be found under “/etc/skel/.bashrc”, simply coping that over your profiles one (found in your home directory) will restore it to default. Make sure to also source the file if you want to continue using it under that terminal or close and re-open the terminal.

I managed to have a blank bashrc after upgrading Ubuntu with a separate /home partition, while deleting all the old config files I must have also removed this.

The following commands should do this for you, be sure to make a back up of your current .bashrc file too, just to be safe.

cp ~/.bashrc ~/.bashrc.bkup
cp /etc/skel/.bashrc ~/
source .bashrc

You should be now back to a default terminal experience and continue to customise it how you like!

HowTo Linux Ubuntu

mlbviewer 2012 Installation guide for Ubuntu (MLB.TV on Linux)

Download mlbviewer:

Go and grab the latest version from the sourceforge page below:


tar -zxvf mlbviewer2012.tar.gz

It doesn’t require any installation but you will need a few extras and the easiest way to install them is shown below:

Download PyXML:

PyXML is an XML processing tool for python which this project uses, sometimes it can be tricky to install python modules so we’ll be using setuptools which you can get from the link below.

If you’re unsure of what version you need, open terminal and type “python”, this will show the version of python you’re running. Mine was 2.7.4 so I downloaded “setuptools-0.6c11-py2.7.egg” I would imagine yours would be similar.

Once you have it, run it (replacing the version you downloaded for the one here):

sudo sh setuptools-0.6c11-py2.7.egg

Now to install PyXML it’s as simple as running:

sudo easy_install pyxml

That’s it, you’re done.

Optional – Install MPLAYER2:

MPLAYER2 offers at lot of advantages over MPLAYER however we’re most interested in it because it offers better streaming support and handle stream rate switches (important if you enable adaptive streaming in nexdef mode).

sudo add-apt-repository ppa:motumedia/mplayer-daily
sudo apt-get update
sudo apt-get install mplayer2

(Thanks to – Web Upd8)

Optional – Install mlbhls (for nextdef | HD):

Instructions as per in REQUIREMENTS-2012.txt in the mlbviewer package.

You’ll also need some extra packages which aren’t stated:

sudo apt-get install libconfig-dev libcurl4-gnutls-dev
svn co mlbhls
cd mlbhls
sudo cp mlbhls /usr/bin

Once that’s done, you should be able to get the higher bitrate streams too!

Using mlbplayer:


The first time you run mlbviewer it will generate a config file which you’ll need to enter your Premium MLB.TV account details in, running mlbviewer will tell you where this file is located:


Go edit the file and enter your email as the “user” and your password after “pass”.

Now re-run mlbviewer and it should start up!


Sit back and enjoy!