Using H.265 (HEVC) on Ubuntu

If you google search how to install H.265 on ubuntu you get a a bunch of posts that describe how to add a PPA for the necessary files.

However the repository hasn't been updated since 2015 (vivid vervet)

If you try to use the vivid repo then things fail because of dependency issues.

But not to worry as it seems that H.265 is now included in the standard xenial repository.

apt-cache search x265
libx265-79 - H.265/HEVC video stream encoder (shared library)
libx265-dev - H.265/HEVC video stream encoder (development files)
libx265-doc - H.265/HEVC video stream encoder (documentation)
x265 - H.265/HEVC video stream encoder

So, all you need to do is;

sudo apt-get install x265

and you are good to go.

Using docker on Linux Mint Debian Edition

Installing Docker on LMDE takes a few steps and will require that we add a third-party repository.

Note: We will be logged in as root to issue these commands. Also, I am by no means an expert on this, I am learning this as I go on.

So, with that out of the way let's add the key for the get.docker.io repository;

# apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9

Next add the repository to your apt sources;

# echo "deb http://get.docker.io/ubuntu docker main" > /etc/apt/sources.list.d/docker.list

Update apt;

# apt-get update

Install docker;

# apt-get install lxc-docker

Verify that it has worked by downloading and running the ubuntu container;

# docker run -i -t ubuntu /bin/bash
Unable to find image 'ubuntu' locally
Pulling repository ubuntu
e54ca5efa2e9: Download complete
511136ea3c5a: Download complete
d7ac5e4f1812: Download complete
2f4b4d6a4a06: Download complete
83ff768040a0: Download complete
6c37f792ddac: Download complete
root@46ec4b13f756:/#

Congratulations you are sitting in bash inside your ubuntu container. Type 'exit' or use ctrl-d to exit.

Note: It is important to understand that once you exit a container it ceases to run unless you specifically tell it not to (see below). It is not like a normal virtual machine that keeps on running in the background until you shut it down. To exit a container and have it remain running, use ctrl-p followed by crtl-q.

You probably dont want to be the root user every time you use docker. In that case simply add your user to the docker group;

# usermod -a -G docker myusername

You can list all the running containers with the 'docker ps' command. Add '-a to see the stopped ones as well.

Note: The containers that you create are kept in '/var/lib/docker/containers'

That's the basics of docker. The next thing to learn more about is using docker files to build containers.

Fix FontConfig Warning in LMDE

I found another bug in Mint Debian relating to how fonts are setup.

Originally I found the issue while playing about in imagemajick which would produce an error like this.

"Fontconfig warning: "/etc/fonts/conf.d/53-monospace-lcd-filter.conf", line 10: Having multiple values in isn't supported and may not work as expected"

You can reproduce that error using this command;

fc-match sans

So, I opened up the file referenced in the error and found it was an XML file.

In the element test name="family" there were two fonts configured, in my case these were "DejaVu Sans Mono" and "Bitstream Vera Sans Mono".

Now, considering that the error was complaining about not liking having two values present, I decided to remove one. I removed the second one.

After doing that things behaved in much more polite way;

fc-match sans
DejaVuSans.ttf: "DejaVu Sans" "Book"

Problems connecting to libvirtd (KVM) on remote hosts

I ran into this annoying bug trying to connect using SSH (key auth) to libvirtd (running on CentOS6) from a LMDE host.

The error I received was unhelpful.

Unable to connect to libvirt.

Cannot recv data: Value too large for defined data type

Verify that the 'libvirtd' daemon is running
on the remote host.

I was pretty sure that the problem was not with the server running libvirtd because it had been working the day before and was unchanged since then. On the other hand my LMDE install was completely fresh.

To cut the chase I don't know what the fix is (it seems to be a bug).

If you read to the end of that bug thread it seems you can work around the problem by using the hostname instead of its FQDN.

For this to work of course you need to be able to resolve the target IP address using just the hostname. Since I was on the same domain as the libvirt server this was simply a matter of defining the domain in /etc/resolv.conf on the client.

domain tuxnetworks.net

If that is not a practical solution (because your client and server on different domains) I reckon you could probably configure the server hostname as an individual entry in your /etc/hosts file too, although I have not tried that. Let me know in the comments if that works for you!

Adding a PPA

I'll use the Handbrake video encoder in this example but it will work for any PPA providing you have the correct id string. In this case that is "ppa:stebbins/handbrake-releases"

Add the PPA to your apt repository sources:

sudo add-apt-repository ppa:stebbins/handbrake-releases

If you do an apt-get update now you will probably get an error like this:

W: GPG error: http://ppa.launchpad.net raring Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6D975C4791E7EE5E

Add the key like this, replacing the key at the end of the command with the one from your previous key error output.

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 
6D975C4791E7EE5E

You should be able to update again without errors.

SOLVED: "Permission denied" when mounting sshfs

I've just come across an annoying bug while attempting to mount a directory using sshfs.

sshfs brettg@myserver.net:/home/brettg/test /home/brettg/test
fuse: failed to open /dev/fuse: Permission denied

The normal google search resulted in many, many hits explaining that this is due to the user account not being a member of the 'fuse' group.

Trouble is, my user account is a member of the fuse group:

$ groups
brettg adm cdrom sudo dip plugdev fuse lpadmin sambashare libvirtd


Note: To add your user to the fuse group use this command:

sudo usermod -a -G fuse brettg

The problem is that Mint 14 sets the user permissions on the fuse device incorrectly which results in only the root user being able to mount it.

You can confirm this is the case like this:

$ ls -al /dev/fuse
crw------T 1 root root 10, 229 Mar  9 10:15 /dev/fuse


There are two problems here. The first is that the fuse device is not owned by the fuse group. Fix it like this:

$ sudo chgrp fuse /dev/fuse


The next problem is that the group permissions for the fuse device are set to deny access to everyone. Fix that with:

sudo chmod 660 /dev/fuse


The fuse permissions should now look like this:

$ ls -al /dev/fuse
crw-rw---- 1 root fuse 10, 229 Mar  9 10:15 /dev/fuse


Having done this you should now be able to mount a fuse device (such as sshfs) as a normal user (who belongs to the fuse group of course).

UPDATE
Upon reboot, I noticed that the permissions on the fuse device were partly reset;

$ ls -al /dev/fuse
crw-rw-rwT 1 root root 10, 229 Mar 18 12:03 /dev/fuse


However, this does not appear to have had an adverse effect on my ability to mount. I find this to be somewhat confusing.

FIX: "Hash sum mismatch" on Linux Mint update

OK, here is the scenario.

I have a Linux Mint machine (maya) that has not been booted for some time.

I started it up and decided to do some housekeeping as a prelude to upgrading it to 'Nadia'

The first thing I did was do an apt-get update which failed with "hash sum mismatch" when updating the Mint list (Sorry, I didn't keep a copy of the full error)

Another machine on my LAN is already on Nadia and it apt-get updates fine.

I use apt-cacher-ng, so I disabled this and tried update again. This worked, which led me to believe there was some corrupt file in the cache somewhere. I spent hours trying to nail this and even did apt-get purge apt-cacher-ng followed by a re-install.

None of this worked.

Eventually something twigged in my brain, and I wondered if there was a compatibility problem with the version of apt on this machine. As I said, it's been some time since I updated.

Here is  what I did;

1) Edited sources.list and commented out the single Mint line, leaving just the ubuntu repositories in place. These were updated from 'precise' to 'quantal'.

2) Did an apt-get update, this worked without errors.

3) Upgrade apt (apt-get install apt) this installed about three new files.

4) Edited sources.list again, removing comment from the Mint line and changed it from 'maya' to 'nadia' while I was there.

5) Another apt-get update and this time there were no errors.

From there everything worked as expected and no more hash sum mismatches!

Unmount stale NFS mounts

If you have a stale NFS mount hanging on your system it can cause various programs and utilities to fail. A typical symptom is a hang when using the 'df' command.

In such cases you cant do umount /path/to/stale/nfs because it will say "the device is busy" or words to that effect

To fix this you can unmount it with the 'lazy' option;

umount -l /path/to/stale/nfs

If you don't expect that mount point to ever be available again (for example the nfs server was decommissioned) then make sure you adjust /etc/fstab accordingly.

Remove Subtitles and Audio tracks from MKV files

To remove unwanted audio and subtitle tracks from Matroska (mkv) files you use mkvtools; sudo apt-get install mkvtoolnix-gui Once it is installed then open up the gui (Sound & Video menu) and follow these steps; 1) In the "Input files" box on the "Input" tab browse to the mkv file you want to modify. 2) In the "Tracks, chapters and tags" box uncheck any part you want to remove (leave the stuff you want to keep checked) 3) In the "Output filename" box keep the default name or modify to suit. 4) Click "Start muxing" and wait a minute or two until it completes. Once you are done, you can delete the original file (after checking it worked of course!) and rename the new file accordingly.

Remove Unwanted Audio Tracks From AVI Files

If you have downloaded videos from certain sources lately, you may have noticed that it is now possible to create a video container (AVI,MKV) that includes multiple audio channels just like on a DVD.

This is a great thing because it allows people of different languages to use the same video file. Alternately it allows the directors commentary to be included.

That said, I am an English speaker, and I have never had any interest in directors commentaries so all these extra audio tracks represent unwanted data in my movie library.

Also, some files default to playing the commentary or the non English track in some players which is also mildly annoying.

So, in shuch circumstances you can use ffmpeg to remove the unnecessary tracks from an AVI file (I have not tried it for MKV, I will update this page if I do.

Things you need to install are vlc and avconv (avconv is the replacement for ffmpg which is now deprecated)

sudo apt-get install vlc libav-tools

Note: On RedHat based distributions you must install libav. ie:

yum install libav

You can see what audio tracks are available, and select them by opening the video file in vlc and looking in Audio>Audio Track.

Once you have determined which track you want to keep, you can run the file through avconv to strip the unwanted tracks. In this example I use the second map parameter to keep track 2 (ie lose track 1);

avconv -i sourcefile.avi -map 0:0 -map 0:2 -acodec copy -vcodec copy outfile.avi

And that's it, happy Linuxing (is that a word?)



Purge Your System Of Mono

Updated 18/6/2012 for Mint 13 "Maya" / Ubuntu 12.04 "Precise"

If you are not overly happy with having a bastard child of Microsoft installed on your systems and the potential patent issues that may arise from its use then this simple one liner will purge your system of mono and anything that depends on it.

Make sure you read the list of packages to be removed that the apt-get command provides before you go ahead and do it.

sudo apt-get purge mono-4.0-gac

This will remove the following from your system.

The following packages will be REMOVED:
  banshee* libappindicator0.1-cil* libdbus-glib1.0-cil* libdbus1.0-cil* libgconf2.0-cil* libgdata1.9-cil*
  libgkeyfile1.0-cil* libglib2.0-cil* libgmime2.6-cil* libgtk-sharp-beans-cil* libgtk2.0-cil* libgudev1.0-cil*
  liblaunchpad-integration1.0-cil* libmono-addins-gui0.2-cil* libmono-addins0.2-cil* libmono-cairo4.0-cil*
  libmono-corlib4.0-cil* libmono-i18n-west4.0-cil* libmono-i18n4.0-cil* libmono-posix4.0-cil*
  libmono-security4.0-cil* libmono-sharpzip4.84-cil* libmono-system-configuration4.0-cil*
  libmono-system-core4.0-cil* libmono-system-drawing4.0-cil* libmono-system-security4.0-cil*
  libmono-system-xml4.0-cil* libmono-system4.0-cil* libmono-zeroconf1.0-cil* libnotify0.4-cil* libtaglib2.0-cil*
  mint-meta-cinnamon-dvd* mono-4.0-gac* mono-gac* mono-runtime* tomboy*
0 upgraded, 0 newly installed, 36 to remove and 0 not upgraded.
After this operation, 34.3 MB disk space will be freed.

If you are happy to lose that stuff, in particular the Banshee audio player then go ahead hit "y" to nuke Mono once and for all*

* Actually, next time you do a dist-upgrade you are likely to have the mono infection return to your system. In such cases just reapply this treatment.

UPDATED: Using SSMTP to send mail via GMail

UPDATED July 2014, to reflect the fact that google smtp servers are on port 587 now.

Often you will have a bash script that requires the ability to send emails out, such as alerts and status updates. Or perhaps you just want to get the normal alerts that all Unix servers attempt to send from time to time.

Out of the box Linux systems don't send email unless they are configured to do so. You can muck about configuring sendmail to use a "smarthost" if you like or you can do what I do and use a simple little smtp service that is quick and easy to configure to send mails via a GMail account.

Note:

If you have your own domain then it is probably better to use sendmail to send mails direct rather than relaying mail via the Big G

Obviously, for this all to work you will need a GMail account of your own. Is GMail still invite only? I have no idea. If it is and you need an invite then enter a comment below with your email address and I will be happy to send you one!

OK, let's get started.

First we need to remove sendmail and install ssmtp

sudo apt-get remove sendmail
sudo apt-get install ssmtp mailutils

SSMTP requires a little configuring so edit /etc/ssmtp/ssmtp.conf;

sudo vi /etc/ssmtp/ssmtp.conf

Enter the details for the following fields;

mailhub = smtp.gmail.com:587
rewritedomain = tuxnetworks.com
AuthUser=myusername@gmail.com
AuthPass=mypassword
UseSTARTTLS=YES
UseTLS=YES

Note:

You should replace "tuxnetworks.com" with your own domain as well as provide the details for your GMail account. Using 'myusername' and 'mypassword' is a recipe for FAIL

Testing to see if things work.

Send an email from the command line like this;

mail -s "test config" myusername@gmail.com

To see if it was sent you can check /var/log/mail.log;

tail -f /var/log/mail.log

You should see your email logged as "SENT" in the output there.

Here is a sample ssmtp.conf for your convenience;

#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=postmaster

AuthUser=myusername@gmail.com
AuthPass=mypassword
UseSTARTTLS=YES
UseTLS=YES

# place where the mail goes. The actual machine name is required no 
# MX records are consulted. Commonly mailhosts are named mail.domain.com
mailhub=smtp.gmail.com

# Where will the mail seem to come from?
rewriteDomain=tuxnetworks.com

# The full hostname
hostname=myserver.tuxnetworks.com

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
FromLineOverride=yes

And that's it! Simples!

[ Tested and confirmed on Lucid and Natty servers ]