The Standard Output (linux)

Convert a PKCS #12 file into certificate and key files

Jonas Gorauskas — Wed, 11 Nov 2015 03:43:09 GMT

In cryptography, PKCS #12 is one of the family of standards called Public-Key Cryptography Standards published by RSA Laboratories. It defines an archive file format for storing many cryptography objects as a single file. It is commonly used to bundle a private key with its X.509 certificate or to bundle all the members of a chain of trust. A PKCS #12 file may be encrypted and signed. The internal storage containers, called SafeBags, may also be encrypted and signed. A few SafeBags are predefined to store certificates, private keys and certificate revocation lists. The filename extension for PKCS #12 files is .p12 or .pfx. These files can be created, parsed and read out with the OpenSSL pkcs12 command.

I'm going to show you the commands used to convert a .pfx file into its certificate and key components. This information can come in handy when you need to import your certificates to devices like routers, load-balancers, handhelds, or for use with webservers like apache or nginx, where you'll need to import the certificates and key files in plain-text, unencrypted format. Follow these steps:

Install openssl

Extract the private key:

openssl pkcs12 -in filename.pfx -nocerts -out encryptedkey.key

Enter the .pfx file password when prompted
Enter a new password for the encrypted key when prompted

Extract the client certificate:

openssl pkcs12 -in filename.pfx -nokeys -clcerts -out certificate.crt

Extract the Certificate Authority certificates:
```
openssl
```

Sometimes you will need an unencrypted key file:

openssl rsa -in encryptedkey.key -out decryptedkey.key

Enter the key password you created in step 4 above

Sometimes the private key needs to be in a PEM format:

openssl rsa -in encryptedkey.key -outform PEM -out encryptedkey.pem

Always remember to keep your decrypted key in a safe place. Those are the literal keys to the kingdom.

Kernel fails to load after Catalyst update

Jonas Gorauskas — Sun, 11 Oct 2015 20:13:13 GMT

Today I did a system update on my Arch Linux installation with the command yaourt -Syua and after that the Kernel refused to boot with an error message similar to the following in journalctl -b:

kernel: RIP firegl trace+0x61/0x1e0

There is a know problem with the proprietary catalyst drivers not supporting linux kernels >= 4.2. So to fix this issue you have to configure the bootloader to use a different kernel, such as linux-lts. Install linux-lts package and then reinstall the catalyst* packages from the Vi0L0 AUR repos and then re-configure GRUB with grub-mkconfig -o /boot/grub/grub.cfg.

I had to boot and mount everything using the Arch live install system then chroot and reinstall the catalyst packages with the LTS kernel to fix the issue.

When rebooting make sure to pick the LTS kernel from the GRUB menu.

Vi0L0 himself has crated a bug for this at the Unofficial AMD Bugzilla, but a fix may take a long time if past behavior is any indication of current outcome.

Evaluating Ersatz Emacsen

Jonas Gorauskas — Tue, 21 Jul 2015 10:57:44 GMT

I have been an Emacs user for many years and the key sequences have become ingrained muscle memory to me. Since most Linux or BSD distros come with vi installed by default, I have learned how to use it. But I still long for that familiar fell of Emacs under my fingers and, at the same time, wish there was something with a smaller footprint than full GNU Emacs.

Well, such software does exist, under many different implementations as a matter of fact. They are affectionately called Ersatz Emacs. Now that's a word your don't see every day, Ersatz. Search google for ersatz definition and you get the following:

er·satz

ˈerˌzäts,ˈerˌsäts/

adjective

(of a product) made or used as a substitute, typically an inferior one, for something else. "ersatz coffee" synonyms: artificial, substitute, imitation, synthetic, fake, false, faux, mock, simulated; More

not real or genuine. "ersatz emotion"

It seems that we can think of a an Ersatz Emacs as a fake emacs. And the Emacs Wiki pretty much confirms that:

A 'nonextensible imitation' of a supposed implementation of an Emacs;

The culprits

The most common Ersatz implementations of Emacs today are mg, jove, and zile. First let's learn a little bit about each of them.

Mg is a lightweight public-domain Ersatz Emacs, dating back to 1986. Mg was originally known as Micro GNU Emacs, as it strove to adhere more closely to the default behavior of GNU Emacs than other contemporary Ersatz Emacsen, but was renamed at the request of Richard Stallman. Modern versions of mg are maintained as a component of the OpenBSD source tree; the editor is included as standard in OpenBSD because there shouldn’t be any reason to learn more editor types than emacs or vi. There is also a port available for Linux.

JOVE (Jonathan’s Own Version of Emacs) is an open-source Ersatz Emacs implementation. JOVE is primarily intended for Unix-like operating systems, but also supports MS-DOS and Microsoft Windows. JOVE was inspired by Gosling Emacs but is much smaller and simpler, lacking any form of LISP or other extension language. It was originally created in 1983 by Jonathan Payne while at Lincoln-Sudbury Regional High School in Massachusetts, USA on a PDP-11 minicomputer. JOVE was distributed with several releases of BSD Unix, including 2.9BSD, 4.3BSD-Reno and 4.4BSD-Lite2.

GNU Zile ("Zile Implements Lua Editors") "is a text editor development kit, so that you can (relatively) quickly develop your own ideal text editor without reinventing the wheel for many of the common algorithms and data-structures needed to do so". Prior to version 3 its name expanded to "Zile Is Lossy Emacs". Its goal was to be a lightweight Ersatz Emacs from the Free Software Foundation emulating the behavior of its "big brother" in a small package, so that Emacs users can feel at home in limited environments. For customization, Zile uses its own limited configuration language known as Zile Lisp. Zile Lisp is a tiny subset of Emacs Lisp that consists of the Zile commands plus setq.

Comparison

The main goal is to pick an Emacs-like editor to be used for quick edits in a virtual host running a flavor of Debian Linux. To that end, I do not require any customisation of the editor, and I want the smallest footprint in both disk and memory.

Implementation	First Appeared	Latest Version	Programming Language	License
mg	1986	20150316 (linux port)	C	Public Domain
jove	1983	4.16.0.73	C	Jove License
zile	2005	2.4.11	C	GNU GPL

And for the technical details:

		Memory
Implementation	Size on Disk	Virtual	Physical	Shared
mg	181 KB	10564 KB	2472 KB	2284 KB
jove	197 KB	8744 KB	2648 KB	2180 KB
zile	260 KB	47272 KB	3968 KB	2584 KB

The difference between Virtual, Physical, and Shared Memory

Time for a quick digression into what the different types of memory mean in Linux.

Virtual memory is the virtual size of a process, which is the sum of memory it is actually using, memory it has mapped into itself (for instance the video card's RAM for the X server), files on disk that have been mapped into it (most notably shared libraries), and memory shared with other processes. Virtual memory represents how much memory the program is able to access at the present moment.

Physical memory stands for the resident size, which is an accurate representation of how much actual physical memory a process is consuming.

Shared memory indicates how much of the Virtual memmory size is actually sharable memory or libraries. In the case of libraries, it does not necessarily mean that the entire library is resident. For example, if a program only uses a few functions in a library, the whole library is mapped and will be counted in Virtual and Shared, but only the parts of the library file containing the functions being used will actually be loaded in and be counted under Physical.

Conclusion

zile is the largest on disk and biggest memory hog of the three, so that's and easy cut. jove is slightly larger on disk than mg, but it's Virtual memory size is the best. mg has the smallest footprint on disk and the smallest Physical memory footprint. Plus, all of the BSD's and all the major Linux distros have packages for the mg, so that's the one I am going with.

Renew IP lease on Linux

Jonas Gorauskas — Sat, 13 Jun 2015 19:39:19 GMT

I run a router at home with dd-wrt. My main machine has a static IP lease based on the MAC address. Sometimes when I reboot the main machine the static IP is not properly released by the DHCP subsystem and the router holds on to it, therefore assigning my machine a regular DHCP IP.

To fix this without having to reboot the machine, follow these steps:

Login to the dd-wrt router.
Go to the Setup page and click the Save button followed by the Apply button. This will restart the DHCP daemon in the router without having to reboot it.
Go to the Status page on the router and click on the Lan tab and verify that the IP was indeed released.

On the main machine, run the following commands:

sudo dhclient -v -r enp4s0
sudo dhclient -v enp4s0

The above will renew the IP lease to the default static IP assigned to that MAC address. Note that the above assumes you are using NetworkManager with dhclient under it and that your network interface is enp4s0.

Fixing package-query to pacman dependency in Arch Linux

Jonas Gorauskas — Sat, 17 Jan 2015 03:07:51 GMT

I was recently trying to update my Arch Linux system and I ran into a peculiar dependency error with package-query that would complety halt the update.

error: failed to prepare transaction (could not satisfy dependencies)
:: package-query: requires pacman<4.2

It turns out that this is totally expected and it has to do with the new version of Pacman (4.2) breaking a few things related to backwards compatibility. This changes will require me to recompile and reinstall package-query and yaourt and here's how to do it:

Uninstall package-query and yaourt

sudo pacman -Rdd package-query
sudo pacman -Rdd yaourt

Get the latest bits from the AUR

curl -O https://aur.archlinux.org/packages/pa/package-query/package-query.tar.gz
curl -O https://aur.archlinux.org/packages/ya/yaourt/yaourt.tar.gz

Explode the tarball and go into the each folder

tar -zxf package-query.tar.gz
tar -zxf yaourt.tar.gz
cd package-query

Compile
```
makepkg -s
```

Install

sudo pacman -U package-query-1.5-2-x86_64.pkg.tar.gz

Make sure to do steps 4 and 5 for the yaourt package also. And this is it... All should be in order now.

Debian: Install Packages that were Kept Back

Jonas Gorauskas — Wed, 03 Dec 2014 02:56:53 GMT

Have you ever seen this message when updating your Debian-based system: "The following packages have been kept back"? Here's why you see it and how to solve it:

You just tried to run the following command:

$ sudo apt-get update && sudo apt-get upgrade --show-upgraded -y

... and you get the message:

The following packages have been kept back

Running apt-get dist-upgrade is dangerous for a stable environment. The wrong source.list setting and you end up with a broken Debian. You might get the entire application upgraded to a version you don't want. For example, the kernel upgrade is kept back. You just want to upgrade the kernel, not the entire distribution.

A better way to handle a kept back package is:

sudo aptitude
If you have kept back package you should see Upgradable Packages on top of the list.
Hit + on that list
Hit g twice
Answer debconf stuff if asked
Press return to continue
Press Q to quit
Press yes

The kept back packages are now installed.

Tracking down where disk space has gone on Linux

Jonas Gorauskas — Tue, 23 Sep 2014 20:03:26 GMT

When administering Linux systems I often find myself struggling to track down the culprit after a partition goes full. Here's a solution which relies on standard Linux commands to find where all that disk space is being consumed.

du -h / | grep '[0-9\.]\+G'

One caveat: Don't go straight to du /. Use df to find the partition that's hurting you, and then try du commands.

Free GeoIp location web service

Jonas Gorauskas — Thu, 04 Sep 2014 05:54:04 GMT

This weekend I found a really cool web service at FreeGeoIp.net. Their API is really simple... just send a HTTP GET request to:

http://freegeoip.net/{format}/{ip_or_hostname}

Here are some of the implementation details:

SSL is supported
Formats are csv, json, and xml
IP is optional. It defaults to your current IP.

I quickly implemented a comnmand line client written in Python 3. It uses the awesome requests library and ElementTree to parse the resulting XML response. Here's the code...

def main():
    args = parse_args()

    MYIP_URL = 'http://freegeoip.net/xml/'
    MYIP_HEADERS = {'Accept': 'application/xml'}

    if args.ip is not None:
        MYIP_URL = MYIP_URL + args.ip

    rspn = requests.get(MYIP_URL, headers=MYIP_HEADERS)
    tree = etree.ElementTree(etree.fromstring(rspn.text))
    root = tree.getroot()

    ip = root.find('Ip')
    cntr = root.find('CountryName')
    reg = root.find('RegionName')
    city = root.find('City')

    print('Your Current IP: %s' % ip.text)
    print('You appear to be in %s, %s, %s' % (city.text, reg.text, cntr.text))

Or you can get the whole code from my github profile.

Quick Ref: Python Virtualenv use

Jonas Gorauskas — Fri, 06 Jun 2014 07:55:33 GMT

Supposing you have a clean install of a Debian-based distro such as Debian 7 proper or Xubuntu 14.04, this notes will walk you through setting up a Python development environment where you can leverage the power of Virtualenv through Virtualenvwrapper.

Why virtualenv?

When you code in python you will quickly find out that different projects have different requirements for the python version you need to use and also the versions of libraries you need to use. Virtualenv will allow you to compartmentalize the requirements on a per project basis without making you install libraries and python versions globally or system-wide.

Ok, ok... Here are the goods...

You have your new shinny install of Debian which comes with a fairly recent version of python pre-installed (somewhere above 2.7.3). Now you need to install a package manager for python and the one I use is pip.

sudo apt-get install python-pip

Once you have pip installed, you will need to also install virtualenv, like so:

sudo pip install virtualenvwrapper

Virtualenvwrapper is a very nice layer on top of virtualenv that makes working with it much more intuitive and convenient.

Next, you may want to automate a couple of things like I did. First, create a ~/.virtualenvs directory. This is where virtualenvwrapper will keep track of your environments. Then open you .bashrc file and add a few lines to it:

export WORKON_HOME=$HOME/.virtualenvs
if [ -f /usr/local/bin/virtualenvwrapper_lazy.sh ]; then
    . /usr/local/bin/virtualenvwrapper_lazy.sh
fi

Now you are ready to start working, so open a new terminal, setup a virtual environment, and start cranking out some python code. Here's a quick reference for virtualenvwrapper:

Start new virtual environment?

mkvirtualenv [env-name]

Leave the current virtual environment?

deactivate

List all available virtual environments?

workon

lsvirtualenv -b

Enter an existing virtual environment?

workon [env-name]

List packages installed in current virtual environment?

pip freeze

Remove a virtual environment?

rmvirtualenv [env-name]

Start a virtual environment with specific python version?

mkvirtualenv [env-name] -p /usr/bin/python3.4

Replace [env-name] above with your actual environment name and enjoy!

Basic WGET usage examples

Jonas Gorauskas — Mon, 24 Feb 2014 08:13:49 GMT

If you have ever used a relatively modern flavor of UNIX, you likely used a tool called wget. It comes as a standard piece of almost every single UNIX variant, Linux included. Here are some ways that I use it on a daily basis:

Download file

wget http://ftp.gnu.org/gnu/wget/wget-1.15.tar.gz

Downloading files with different names

wget http://ftp.gnu.org/gnu/wget/{wget-1.15.tar.gz,wget-1.15.tar.gz.sig}

Multiple downloads using different protocols

wget http://ftp.gnu.org/gnu/wget/wget-1.15.tar.gz ftp://ftp.gnu.org/gnu/wget/wget-1.15.tar.gz.sig

Using an input file

You can use an input file that contains a list of URLs to download, like so:

wget -i ~/Downloads/urls-for-wget.txt

Resume incomplete download

Sometimes a download is interrupted in the middle. To resume a partial download use the -c option, like so:

wget -c http://ftp.gnu.org/gnu/wget/wget-1.15.tar.gz

Download files in the background

Using the option -b sends wget to the background and also saves the output to a log file:

wget -b ~/Downloads/wget-log.txt http://ftp.gnu.org/gnu/wget/wget-1.15.tar.gz

Throttling download speeds

To limit the download speed, use the --limit-rate option:

wget --limit-rate=100k http://ftp.gnu.org/gnu/wget/wget-1.15.tar.gz

Performing downloads with authentication

Some sites restrict access to content by requiring a username and password. wget can handle that:

wget --user=joeschmoe --password=p4sswOrd! http://ftp.gnu.org/gnu/wget/

More information

Of course, you can mix and match all of these options into a single command, like so:

wget -c -b -a ./wget-log --limit-rate=100k http://ftp.gnu.org/gnu/wget/wget-1.15.tar.gz

You can also go much further than what I described above. The script below will check the web page for the latest listed version of wget and then download it and its signature file if the online version is newer than the local one.

wget -qN $(wget -qO- http://ftp.gnu.org/gnu/wget/ \
          | grep tar | cut -d\" -f6 \
          | tail -n4 | grep gz \
          | sed "s|^|http://ftp.gnu.org/gnu/wget/|")

For more information, check online or use man or info.

Running XFCE 4.10 on Debian 7.4

Jonas Gorauskas — Sun, 16 Feb 2014 00:15:26 GMT

The Debian 7 series (a.k.a. Wheezy or stable) repositories are currently serving the xfce4 package at version 4.8 and the upgrade to XFCE 4.10 series is not slated to occur until the next major version relase, known as Jessie or testing currently. But I want to use XFCE 4.10 now...

Luckly, there is a way for me to pick and choose certain packages from different Debian repositories, while still maintaining proper dependencies. So, here's how I installed it on Debian 7:

First I installed the latest Debian stable with a default XFCE desktop. This is version 7.4 at the time of this writing. I got it here.
I installed it with the Desktop, SSH, and Base System options checked.
Next I booted the new Debian 7 system and logged in. I had a default Debian install with XFCE 4.8 desktop.

Next I edited my sources.list file like so:

sudo <editor-of-choice> /etc/apt/sources.list

And inserted the following repository at the bottom of the sources.list file:
```
deb http://ftp.us.debian.org/debian/ testing main
```
I also had to ensure that the default release in the Apt system remained configured to use wheezy. I created a file like so:
```
sudo <editor-of-choice> /etc/apt/apt.conf.d/30default-release
```
In that file I inserted the following directive:
```
APT::Default-Release "wheezy";
```
I saved and closed the files above and then ran the following:
```
sudo apt-get update
```
Then I was able to install XFCE 4.10 by issuing the following command:
```
sudo apt-get -t testing install xfce4 xfce4-terminal
```

Recap

This is what I have done so far: I installed Debian 7 with the default XFCE 4.8 desktop. I edited the sources.list file to add a reference to the Debian testing repository. I made sure that the default Apt repository remained the stable one. Then I updated the Apt system and installed XFCE 4.10 from testing. Note that with the -t option, apt will track the package in the given release until the package version or newer is available in default release.

Let's Make it Look Better

At this point, I logged out and then back in and I had the new XFCE 4.10 desktop available. But that's not quite enough. I wanted to make it look better by installing a good looking theme. My personal favorite theme for XFCE is Greybird.

Let's dispense with the fluff and get down to just the stuff:

sudo apt-get install gtk-engine-murrine
mkdir ~/.themes
cd ~/Downloads/
git clone https://github.com/shimmerproject/Greybird
cp -R Greybird ~/.themes

Then I used XFCE Settings Manager to set the Appearance and the Window Manager settings to use the new Greybird theme.

I also installed the Faenza icon theme:

mkdir ~/Downloads/faenza
cd ~/Downloads/faenza
wget http://faenza-icon-theme.googlecode.com/files/faenza-icon-theme_1.3.zip
unzip faenza-icon-theme_1.3.zip
sudo ./INSTALL

Running as sudo will install the theme globally in /usr/share/icons. Also ensure that the permissions on the Faenza folders under /usr/share/icons is properly set to drwxr-xr-x.

That's it... Enjoy!

Connecting to a Cisco VPN from Linux

Jonas Gorauskas — Fri, 27 Dec 2013 06:15:00 GMT

The folks at the new job are running a Cisco VPN. While it's very straight forward to connect using the AnyConnect client from Windows, the steps to do it in Linux are not so clear cut, because the AnyConnect client for Linux constantly drops the connection for me and won't hold it for more than 30 seconds. So, this is how you do it from a Debian-based Linux:

Install the "network-manager-openconnect-gnome" package

sudo apt-get install network-manager-openconnect-gnome

Open the Network Manager applet from the task bar
Click on VPN Connections
Click Configure VPN...
Click the Add button
VPN Connection Type should be Cisco AnyConnect Compatible VPN
Enter a name for your connection
Enter a value for the Gateway (IP or Host Name)
Click Save
Then go back to the Network Manager applet on the task bar
Select VPN Connections and then select the one you just created
On the Connect to VPN dialog, choose the VPN host and
Click the Conect button
Enter your Username and Password
Lastly, click Login

This approach has been working really well and reliably for me and I hope it will for you too.

Manage your PostgreSQL Database from a Remote Machine

Jonas Gorauskas — Fri, 29 Nov 2013 05:56:11 GMT

At home I have my main development workstation and then I spin up VMs that mimic my production environment to run different types of integration tests. One of these VMs is running a relatively recent version of PostgreSQL. By default, PostgreSQL is setup to allow connections coming from the local host only. In this article I will walk through the steps of setting up PostgreSQL so that it allows connections from other machines also.

Setup Remote Connections

There are, essentially, two lines in two different PostgreSQL configuration files that need to be changed to allow remote connections to work. The first file is postgresql.conf and this is usually found at /etc/postgresql/9.1/main/ on Debian-based systems. Open that file and find the line that starts with listen_addresses. By default the value assigned to it should be 'localhost'. Change that so the line reads like this:

listen_addresses = '*'

The second file is called pg_hba.conf. In this file you need to look for a IPv4 local connections line that starts with host. By default, the line reads the following:

host    all             all             127.0.0.1/32            md5

You need to change this line to read like this:

host    all             all             10.0.0.0/24             trust

For all intents and purposes, the default is telling PostgreSQL to accept connections only from the localhost (that's what the /32 is for), while we are changing the value to allow any host with an IP starting with 10.0.0.* to connect. The above will only work after you restart PostgreSQL with the following command:

sudo /etc/init.d/postgresql restart

Again, YMMV if you are using anything other than Debian.

Allowing Connections Through a Firewall

The above is really all you have to do with PostgreSQL proper to allow remote connections. But if you are like me, you are probably running a firewall on your systems also and you will need to punch a whole for PostgreSQL to talk through. You can find out more about how I setup my IPTables firewall by reading this. In my case, I need to allow only one system (my workstation) to connect to the VM hosting PostgreSQL. I created the following lines in my IPTables configuration file:

# Allow connections to Postgres DB Server from hurricane
-A INPUT -p tcp -s 10.0.0.90 --sport 1024:65535 -d 10.0.0.60 --dport 5432 \
         -m state --state NEW,ESTABLISHED -j ACCEPT
-A OUTPUT -p tcp -s 10.0.0.60 --sport 5432 -d 10.0.0.90 --dport 1024:65535 \
         -m state --state ESTABLISHED -j ACCEPT

In the above, the first line allows traffic on port 5432 into the local system from the 10.0.0.90 IP address, which is my development workstation. The second line allows the local system to send traffic out via port 5432, which is the default port used by PostgreSQL.

Conclusion

To allow remote connections to your PostgreSQL instance, all you have to do is edit postgresql.conf and pg_hba.conf. Also remember to address firewall configuration issues that may arise.

Resume interrupted downloads with cURL in Linux

Jonas Gorauskas — Mon, 14 Oct 2013 04:59:23 GMT

I have recently been trying to download an ISO of a certain Linux distro, but I find myself at the wrong end of a crappy connection. I tried downloading it with both Firefox and Chrome but both choked very early in the process and current speed would go down to 0 and after a while the connection would just cutoff with no way to resume the download from where I left off.

Fear not because [cURL][curl] comes to the rescue. After typing Up-Arrow and Enter more time than I care to admit, I decided to let the computer do the hard work and automate this thing. So I created a small Bash script called acurl.sh (for Automated cURL) that looks like this:

export ec=1;

while [ $ec -gt 0 ]; do
    /usr/bin/curl -O -C - $1;
    export ec=$?;
done

if [ $ec -eq 0 ]; then
    echo "Downloaded $1";
fi

What's going on above is that I have a while loop that is checking the exit code of curl. This exit code is captured by assigning the value of $? to the variable $ec. If curl exit code is larger than 0 then continue trying to download the file, which is represented by parameter $1, from where we left off, which is accomplished by passing the parameter -C to curl.

Assuming that the script above is located somewhere in the $PATH, then using it is as simple as this:

acurl.sh http://distrodomain.org/downloads/linux-distro-version-platform.iso

This is definitely a brute force approach, but it does the work.

[curl]: http://curl.haxx.se/ "cURL"

How to Change the Default Browser in Xubuntu

Jonas Gorauskas — Sun, 13 Oct 2013 03:38:00 GMT

I am using Xubuntu 12.04 on my main workstation at home and for the longest time I have been trying to make Google Chrome my default browser on that machine. I've tried several things that didn't work or worked but would not persist when I rebooted the machine. Well, that changed just recently...

Recently I found out that there is a configuration file at ~/.local/share/applications/mimeapps.list that you can change and make it stick. Just replace all references to firefox.desktop with google-chrome.desktop.

Here are the relevant current values:

[Added Associations]
x-scheme-handler/http=exo-web-browser.desktop;google-chrome.desktop;
x-scheme-handler/https=exo-web-browser.desktop;google-chrome.desktop;
...
x-scheme-handler/ftp=google-chrome.desktop;
x-scheme-handler/chrome=google-chrome.desktop;
text/html=google-chrome.desktop;
application/x-extension-htm=google-chrome.desktop;
application/x-extension-html=google-chrome.desktop;
application/x-extension-shtml=google-chrome.desktop;
application/xhtml+xml=google-chrome.desktop;
application/x-extension-xhtml=google-chrome.desktop;
application/x-extension-xht=google-chrome.desktop;

[Default Applications]
...
application/x-mimearchive=google-chrome.desktop
...
x-scheme-handler/http=google-chrome.desktop
x-scheme-handler/https=google-chrome.desktop
x-scheme-handler/ftp=google-chrome.desktop
x-scheme-handler/chrome=google-chrome.desktop
text/html=google-chrome.desktop
application/x-extension-htm=google-chrome.desktop
application/x-extension-html=google-chrome.desktop
application/x-extension-shtml=google-chrome.desktop
application/xhtml+xml=google-chrome.desktop
application/x-extension-xhtml=google-chrome.desktop
application/x-extension-xht=google-chrome.desktop

The ... above means that I omitted 1 or more lines for brevity. Hope this works for you too.

Burn an ISO to a USB stick

Jonas Gorauskas — Fri, 11 Oct 2013 07:20:26 GMT

Several of the Debian CD and Debian Live images are created using isohybrid technology, which means that they may be used in two different ways:

They may be written to CD/DVD and used as normal for CD/DVD booting.
They may be written to USB flash drives, bootable directly from the BIOS of most PCs.

The most common way to copy an image to a USB flash drive is to use the dd command on a Linux machine:

dd if=file.iso of=/dev/device bs=4M; sync

where:

file.iso is the name of the input image, e.g. netinst.iso
/dev/device is the device matching the USB flash drive, e.g. /dev/sda, /dev/sdb. Be careful to make sure you have the right device name, as this command is capable of writing over your hard disk just as easily if you get the wrong one!
bs=4M tells dd to read/write in 4 megabyte chunks for better performance; the default is 512 bytes, which will be much slower
The sync is to make sure that all the writes are flushed out before the command returns.

Virtual Box Fails to Start Virtual Machine

Jonas Gorauskas — Thu, 13 Jun 2013 04:17:02 GMT

I recently moved to a new house and during the move something really peculiar occured with my computer: It seems that the UEFI chip reset to the factory defaults. The 2 visible outcomes of this was that the computer clock was reset back to 2009-01-01 00:00:00 and that the Hardware Virtualization on the CPU was turned off. The latter manifested itself as an error when I tried to run virtual machines with Virtual Box. This was the error generated by Virtual Box:

To fix these errors I had to first set the correct system date and timezone offset and then I had to boot into the UEFI setup utility and enable hardware virtualization for the Intel i7 CPU. This setting is going to be slightly different on every motherboard, but after I enabled it VBox started to run the VMs as usual.

Install the Real Firefox on Debian 7

Jonas Gorauskas — Sun, 02 Jun 2013 09:35:22 GMT

If you have ever played around with the Debian distribution proper, you will quickly notice that Firefox is not available as a browser and in its place is something called IceWeasel. Here I will show you how to install the real Firefox browser on Debian 7.

The first step is to remove the IceWeasel package if it's installed:

$ sudo apt-get remove iceweasel

Next, we will make use of a Linux Mint package repository that targets Debian proper. To do this add the following line to you /etc/apt/sources.list file:

deb http://packages.linuxmint.com debian import

Now when you update your package list you will see an error like so:

$ sudo apt-get update
... a ton of output ...
W: GPG error: http://packages.linuxmint.com debian Release: The following
signatures couldn't be verified because the public key is not available:
NO_PUBKEY 3EE67F3D0FF405B2

This happens because you don't have the proper key for the Linux Mint repository. To get a valid PGP key do the following:

$ sudo gpg --keyserver pgp.mit.edu --recv-keys 3EE67F3D0FF405B2
$ sudo gpg --export 3EE67F3D0FF405B2 > 3EE67F3D0FF405B2.gpg
$ sudo apt-key add ./3EE67F3D0FF405B2.gpg
$ sudo rm ./3EE67F3D0FF405B2.gpg

Now you should be able to update the package list successfully. Then what's left to do is to install firefox and you can do that like so:

$ sudo apt-get install firefox firefox-l10n-en-us

Enjoy firefox!

Build Emacs from Source in Ubuntu 13.04

Jonas Gorauskas — Mon, 06 May 2013 22:28:28 GMT

Over the years I have written several of these articles and I find that every 2 to 3 years I need to re-write these notes because the installation process diverges enough from the previous set of steps that it warrants a re-write.

The main Linux distribution that I have settled on lately is Xubuntu, which is a XFCE-based version of Ubuntu. I dabble in other distros also and I am experimenting a lot lately with Arch and other Debian-based distros. One thing is clear, the versions of GNU Emacs available with each distribution are different. So, as a standard I will always try to download the latest stable GNU Emacs sources and build it on the system I am using at the moment. This ensures that I have a homogeneous set of features across the different machines and also that I am pretty close to the bleeding edge.

In order to get to this state with your Emacs install you can follow the below steps. These steps are focused on a Debian-based distro using APT. I will assume that you have a base Debian or Ubuntu system already installed with a common GUI environment. Again, I wrote these notes for a Xubuntu system running XFCE. Let's start by downloading and installing the tools needed to build Emacs:

$ sudo apt-get install build-essential git git-core curl
$ sudo apt-get install automake autogen autoconf ssh

Next, you need to get the sources for Emacs. There is two ways to go about doing this: 1) Clone the sources from an Emacs repository directly or 2) Download the latest compressed source tarball from a FSF/GNU mirror site.

To clone the Emacs source from a repo, do the following:

$ cd ~/Downloads
$ git clone git://git.savannah.gnu.org/emacs.git

Cloning will take several minutes, because git will get all the history and changes and we all know that Emacs has a long history. The clone method is the way to go for those who will hack on emacs itself. The easier way to do this, however, and the way that I prefer is to pull the source tarball from a mirror. A list of available mirrors can be found at the FSF site. You can pick any of these sites and download from it. The command to do that will differ based on the mirror you pick, but should look something like this:

$ curl -O http://mirror.sdunix.com/gnu/emacs/emacs-24.3.tar.gz

While you are downloading the tarball or cloning the repo you should open another terminal window and start installing some needed Emacs dependencies in parallel:

$ sudo apt-get install texinfo libncurses5-dev libgtk2.0-dev libgif-dev
$ sudo apt-get install libjpeg-dev libpng-dev libxpm-dev libtiff4-dev
$ sudo apt-get install libxml2-dev librsvg2-dev libotf-dev libm17n-dev
$ sudo apt-get install libgpm-dev libgnutls-dev libgconf2-dev libdbus-1-dev

Once the above deps are installed and you finished retrieving the sources for Emacs, it's time to do the actual build. Decompress the source if you downloaded it and change directory into the Emacs source:

$ tar -zxvf emacs-24.3.tar.gz
$ cd ~/Downloads/emacs-24.3/

Configure the build according to what you want your installation to look like:

$ sudo ./autogen.sh
$ ./configure

I use the vanilla configuration, but you can change it to what suits you best and you can view all alternatives by using ./configure --help ... If you don't like what configure has done for you (read the configure output) you can also clean things up and start over with make distclean.

The key thing that I am trying to achieve is a message from configure that looks very similar to the below output. Note all the yes values next to all the stuff that configure checks for; this is a direct outcome of installing all the dependency packages above. Emacs absolutely needs texinfo, ncurses, an X toolkit and the image libraries to even build. The rest of the stuff is nice to have, but if you don't install it you will get a no from configure for that feature check.

... a ton of output

Configured for `x86_64-unknown-linux-gnu'.

  Where should the build process find the source code?    ~/Downloads/emacs-24.3
  What compiler should emacs be built with?               gcc -std=gnu99 -g3 -O2
  Should Emacs use the GNU version of malloc?             yes
      (Using Doug Lea's new malloc from the GNU C Library.)
  Should Emacs use a relocating allocator for buffers?    no
  Should Emacs use mmap(2) for buffer allocation?         no
  What window system should Emacs use?                    x11
  What toolkit should Emacs use?                          GTK2
  Where do we find X Windows header files?                Standard dirs
  Where do we find X Windows libraries?                   Standard dirs
  Does Emacs use -lXaw3d?                                 no
  Does Emacs use -lXpm?                                   yes
  Does Emacs use -ljpeg?                                  yes
  Does Emacs use -ltiff?                                  yes
  Does Emacs use a gif library?                           yes -lgif
  Does Emacs use -lpng?                                   yes
  Does Emacs use -lrsvg-2?                                yes
  Does Emacs use imagemagick?                             no
  Does Emacs use -lgpm?                                   yes
  Does Emacs use -ldbus?                                  yes
  Does Emacs use -lgconf?                                 yes
  Does Emacs use GSettings?                               yes
  Does Emacs use -lselinux?                               no
  Does Emacs use -lgnutls?                                yes
  Does Emacs use -lxml2?                                  yes
  Does Emacs use -lfreetype?                              yes
  Does Emacs use -lm17n-flt?                              yes
  Does Emacs use -lotf?                                   yes
  Does Emacs use -lxft?                                   yes
  Does Emacs use toolkit scroll bars?                     yes

... more output

Now you can go into the actual build of Emacs by issuing the following command:

$ make

And then last step is to install the Emacs you just finished building:

$ sudo make install

... and run it:

$ emacs &amp;

Enjoy hacking with Emacs!

P. S. One last step that is personal and relevant to me only is to install my Emacs configuration. Execute the following to accomplish that:

$ rm -r .emacs.d
$ git clone git@github.com:gorauskas/.emacs.d.git

You will of course need to have the correct encryption key in order to clone the repo like the line above.

Grepping Multiple Files Recursively

Jonas Gorauskas — Thu, 18 Apr 2013 04:26:25 GMT

Recently I was faced with the task of looking for the occurences of a variable name in all files in a directory recursively. Here is a quick bash incantation that accomplishes that:

$ find . -type f -print0 | xargs -0 grep -l variable-name

The above can be understood better if we break it down at the pipe character. To the left of the pipe we use the find command to generate a list of file names recursively starting at the current directory. We use find with the -print0 action because we are passing the output to another program via a pipe and this way the list of file names come out delimited by a null character. Next, we feed the output of find to the input of xargs which will split the long list of file names into sublists and calls grep once for every sublist. The grep command then filters the list of file names and returns only the ones that contain the variable-name string in them.

Pretty cool, eh?