Automatically enabling your network connection at startup on CentOS 7

The release of CentOS 7 stoked my curiosity so I gave it a go in a VirtualBox virtual machine. It uses GNOME Shell in classic mode so the feel is not too far removed from that of GNOME 2. One thing to watch though is that it needs at least version 4.3.14 of VirtualBox or the Guest Additions kernel drivers will not compile at all. That might sound surprising when you learn that the kernel version is 3.10.x and that for GNOME Shell is 3.8.4. Much like Debian production releases, more established versions are chosen for the sake of stability and that fits in with the enterprise nature of the intended user base. Even with that more conservative approach, the results still please the eye though attempting to change the desktop background picture managed to freeze the machine. Other than that, most things work fine.

Even so, there are unexpected things to be encountered and one that I spotted was that network connectivity needed to switched on every time the VM was started. The default installation gives rise to this state of affairs and it is a known situation with CentOS from at least version 6 of the distribution and is not so hard to fix once you know what to do.

What you need to do is look for the relevant configuration file in /etc/sysconfig/network-scripts/ and update that. Using the ifconfig command, I found that the name of the network interface. Usually, this is something like eth0 but it was enp0s3 in my case so I had to look for a file named ifcfg-enp0s3 and edit that. The text that is sought is ONBOOT=no and that needs to become ONBOOT=yes for network connections to start automatically. To do something similar from the command line, CentOS had suggested the following:

sed -i -e ‘[email protected]^ONBOOT=”[email protected]=”[email protected]’ ifcfg-enp0s3

The above uses sed to do an inline (and case insensitve) edit of the file to change the offending no to a yes, once you have dropped in the /etc/sysconfig/network-scripts/ directory. My edit was done manually with Gedit so that works too. One thing to add is that any file editing needs superuser privileges so switching to root with the su command and using sudo is in order here.

Suppressing Update Notifier messages in Ubuntu GNOME 14.04

Though I use only the command line to do system updates, I still got system restart messages every time a new kernel version was installed. While they can be helpful, I actually prefer to be left to my own devices when it comes to restarting a system and I may have a something running at the time that I do not wish to interrupt.

In Ubuntu GNOME 13.10 and before, there was no sign of these messages so I decided to see if I could go nag free again. The responsible application is called Update Notifier and I tried seeing if I could remove it but that act has a major impact of the system so it was not a useful way to go.

As it happens, it is an application that starts up automatically at computer boot time but there was no sign of an entry for it in the Startup Applications Preferences screen (started using from the command line using gnome-session-properties). The for this is that there is flag called NoDisplay in the relevant autostart shortcut in /etc/xdg/autostart/ that stops it appearing in the aforementioned settings screen when set to true. The trick then is to set it to false and the following command (broken over two lines for sake of display and quotes could need replacing when you issue the command too) does the trick for all such hidden start-up applications:

sudo sed -i ‘s/NoDisplay=true/NoDisplay=false/g’
/etc/xdg/autostart/*.desktop

What the above does is that sed goes into every file and changes NoDisplay=true to NoDisplay=false in each file with the desktop extension. When that has completed, there are more entries in Startup Applications Preferences and Update Notifier can be deselected in order to stop it starting. Removing the relevant .desktop file would be a more permanent change but this one will do me, especially since no more of those pesky restart messages appear anymore. My regularity when it came to system updates meant that the update messages never appeared anyway and I tend to shut down my system at the end of every day so the updates will be picked up too so all should be well.

Fixing Background Image Display in GNOME Shell 3.10

On upgrading from Ubuntu GNOME 13.10 to Ubuntu GNOME 14.04, a few rough edges were to be noticed. One was the display of my chosen background image: it was garbled. Later, I discovered that there is a maximum width of 2560 px for background images in GNOME Shell these days and that things get messy beyond that.

In my case, the image width was around 6000 px and I was used to its getting resized in GNOME Shell 3.8 and its predecessors. It seems that the functionality got removed after that though so the workaround of manual image resizing in the GIMP needed to be employed. Though having big images open in memory creates an additional overhead, not handling them very well at all looks like a bug caused by setting 2560 px as a maximum screen width for the GNOME Shell panel and the complete removal of Nautilus from desktop rendering duties. Let’s hope that sense is seen with ever larger screen sizes and resolutions coming our way.

It’s the sort of thing that did get me looking at adding on Cinnamon 2.2 for a while before setting background image scaling using the indispensable GNOME Tweak Tool was discovered. LinuxG.net has a useful tutorial on this for anyone with such an adventurous streak in them. For now though, I am OK with my set up but the GNOME project’s focus on minimalism could affect us in other ways so I can see why Clem Lefebvre started the Cinnamon one primarily for Linux Mint and the desktop environment is appearing elsewhere too. After all, Gedit lost its menu bar in GNOME 3.12 so it’s just as well that we have alternative choices.

Update 2014-05-06: It seems that the desktop image bug that afflicts GNOME Shell 3.10 got sorted for GNOME Shell 3.12. At least, that is the impression that an Antergos instance in a VirtualBox virtual machine gives me.

A fallback method of installing Nightingale in Linux

When I upgraded to Ubuntu GNOME 13.10 and went for the 64-bit variant, I tried a previously tried and tested approach for installing Nightingale that used a PPA only for it not to work. At that point, the repository had not caught up with the latest Ubuntu release (it has by the time of writing) and other pre-compiled packages would not work either. However, there was one further possibility left and that was downloading a copy of the source code and compiling that. My previous experiences of doing that kind of thing have not been universally positive so it was not my first choice but I gave it a go anyway.

In order to get the source code, I first needed to install Git so I could take a copy from the version controlled repository and the following command added the tool and all its dependencies:

sudo apt-get install git autoconf g++ libgtk2.0-dev libdbus-glib-1-dev libtag1-dev libgstreamer-plugins-base0.10-dev zip unzip

With that lot installed, it was time to checkout a copy of the latest source code and I went with the following:

git clone https://github.com/nightingale-media-player/nightingale-hacking.git

The next step was to go into the nightingale-hacking sub-folder and issue the following command:

./build.sh

That should produce a sub-directory named nightingale that contains the compiled executable files. If this exists, it can be copied into /opt. If not, then create a folder named nightingale under /opt using copy the files from ~/nightingale-hacking/compiled/dist into that location. Ubuntu GNOME 13.10 comes with GNOME Shell 3.8, the next step took a little fiddling before it was sorted: adding an icon to application menu or dashboard. This involved adding a file called nightingale.desktop in /usr/share/applications/ with the following contents:

[Desktop Entry]
Name=Nightingale
Comment=Play music
TryExec=/opt/nightingale/nightingale
Exec=/opt/nightingale/nightingale
Icon=/usr/share/pixmaps/nightingale.xpm
Type=Application
X-GNOME-DocPath=nightingale/index.html
X-GNOME-Bugzilla-Bugzilla=Nightingale
X-GNOME-Bugzilla-Product=nightingale
X-GNOME-Bugzilla-Component=BugBuddyBugs
X-GNOME-Bugzilla-Version=1.1.2
Categories=GNOME;Audio;Music;Player;AudioVideo;
StartupNotify=true
OnlyShowIn=GNOME;Unity;
Keywords=Run;
Actions=New
X-Ubuntu-Gettext-Domain=nightingale

[Desktop Action New]
Name=Nightingale
Exec=/opt/nightingale/nightingale
OnlyShowIn=Unity

It was created from a copy of another *.desktop file and the categories in there together with the link to the icon were as important as the title and took a little tinkering before all was in place.  Also, you may find that /opt/nightingale/chrome/icons/default/default.xpm needs to be become /usr/share/pixmaps/nightingale.xpm using the cp command before your new menu entry gains an icon to go with it. While the steps that I describe here worked for me, there is more information on the Nightingale wiki if you need it.

Sorting out hogging of the Super (or Windows) Key by GNOME Shell

Most of the time, GNOME Shell’s use of the Super (or Windows) key on a standard keyboard to open up its dash area is no issue and is a handy counterpart to what you might do in Windows, especially in its latest incarnations. However, it does cause trouble if you are using a VirtualBox virtual machine with Windows installed in there. While VMware Player is immune to this problem I thought that I would see if there was a workaround for it.

The issue might arise from VirtualBox’s non-grabbing of the Super key like others but a solution can be found in GNOME itself. Opening up dconf-editor and navigating to org > gnome > mutter. In there, you will find a setting called overlay-key and this can be changed. One option is to delete the SUPER_L value and leave it that way. My own preference was to set it to a different key and, to do that, I needed to know what the various key identifiers were. To get these, I ran the following command (just replace any quotes with alternatives in the shell before executing this):

xev | grep -A2 --line-buffered ‘^KeyRelease’ | sed -n ‘/keycode /s/^.*keycode \([0-9]*\).* (.*, \(.*\)).*$/\1 \2/p’

This opened up an Event Tester window that will need closing when testing is complete. More importantly, the aliases for any keys that were pressed to are issued to the terminal session so you can see what’s what. Initially, the one for the Alt Gr key appealed to me and I set “ISO_Level3_Shift” as the value of the overlay-key property in dconf-editor. When that didn’t work, I set the value to “Menu” and it behaved as expected. While this will mean that context menus will have to be accessed by right-clicking in a Windows session, that is what I do anyway so there isn’t going to be much of a loss in what I have done. A function key might have been another option but I reckon that the context menu key will do me.