Monday, 18 July 2016

Install Cura 2.1.2 on Fedora 23/24

Unfortunately for Fedora users Ubuntu is more popular which means packages that don't make it into repos often aren't available as RPM's but are sometimes available as DEB's, this was the case with Cura slicer from Ultimaker.

Luckily DEB's can be converted to RPM's with a package called Alien which can be installed through DNF.

Download your preferred version of Cura, I wrote this guide around the recently release version 2.1.2.

Install Alien:
# dnf install -y alien

Convert the DEB to RPM:
# cd ~/Downoads
# alien -vr Cura-2.1.2-Linux.deb

Unfortunately at this point the RPM won't install successfully so it needs to be modified:
# dnf install -y rpmrebuild

Fix the RPM:
# rpmrebuild -pe cura-2.1.2-2.x86_64.rpm

After a short time rpmrebuild will open a file in vi, the below lines need to be removed (move cursor to appropriate line with arrow keys and press the d key twice):

# /opt can be found at the top of the %dir list:
%dir %attr(0755, root, root) "/opt"

# the remaining lines are at the bottom of the file:
%dir %attr(0755, root, root) "/usr"
%dir %attr(0755, root, root) "/usr/bin"
%dir %attr(0755, root, root) "/usr/share"
%dir %attr(0755, root, root) "/usr/share/applications"

Fedora 24 note:
If you are using Fedora 24 you will also need to remove this line and create a symlink, Fedora 24 shipped with Python 3.5 but Cura was built for Python 3.4, this step is not needed for Fedora 23:

Now save and exit, press the : key then type wq and press enter (:wq), rpmrebuild will now now prompt to continue, press Y to build the modified RPM file.

Once rpmrebuild has finished building the new RPM it will return the location of the new RPM:
result: /home/user/rpmbuild/RPMS/x86_64/cura-2.1.2-2.x86_64.rpm

Fedora 24 note:
Before installing create a softlink to a file Cura will be expecting to find but doesn't exist, this step is not needed for Fedora 23:
# ln -s /usr/lib64/ /usr/lib64/

You can now install the new RPM using DNF:
dnf install '/home/user/rpmbuild/RPMS/x86_64/cura-2.1.2-2.x86_64.rpm'

And that should be it, run Cura from the Applications menu and if all went well it will open just fine.

Monday, 11 July 2016

Plex playback failure on Linux

This is my first post on what I hope to be a useful resource for Linux Tips and Tricks.

This evening I had a disagreement with Plex Media Server on my HP Gen 8 Micro Server, it runs a Debian based distro called Open Media Vault, it's pretty slick, check it out.

When I first setup this server with Open Media Vault I used an 8GB USB drive connected to the internal USB port as I didn't think the install would go beyond that, but it turns out the databases and metadata behind Plex Media Server chew up quite a bit of space. So I moved the Plex Library onto a 240GB SSD that is used for VM storage, all was good for quite a while till this evening when I updated Plex and it failed to transcode media, direct play wasn't an issue however.

The log file showed this when ever I attempted to play files from a device that needed to transcode:
Jul 10, 2016 20:50:33.579 [0x7f40a53f9700] ? - [Transcoder] Unknown decoder 'h264'

Googling didn't help much, the best I found was this comment on the Plex forums:

So I had a look at /etc/fstab and the drive that I moved the Plex Library to had the noexec option, noexec prevents execution of binaries and scripts, I remounted the drive with the exec option and Plex worked again!

Here's a quick run down on how you can resolve the issue:

Locate where your Plex Media Server is installed with the find command:
# find / -name ''

/media/fa7154d4-1137-43ab-8720-1ccfe9cad638/plexmediaserver/Library/Application Support/Plex Media Server/Codecs/2c361e4-1071-linux-ubuntu-x86_64/

Check /etc/fstab for the offending entry using the path from the output of the find command:
# grep '/media/fa7154d4-1137-43ab-8720-1ccfe9cad638' /etc/fstab

UUID=fa7154d4-1137-43ab-8720-1ccfe9cad638 /media/fa7154d4-1137-43ab-8720-1ccfe9cad638 ext4 defaults,nofail,user_xattr,noexec,usrjquota=aquota.user,,jqfmt=vfsv0,acl 0 2

Before editing the fstab file you can test by remounting the filesystem with the exec option:
mount -o remount,exec /media/fa7154d4-1137-43ab-8720-1ccfe9cad638/

Use your favourite text editor to change it to exec or leave it out, note that the presence of the "user" option implies noexec unless overridden with exec.

I hope this is even slightly helpful to someone.