Technology Tales

Turning on autocompletion for the bash shell in terminal sessions

At some point, I managed to lose the ability to have tab key based autocompletion on terminal sessions on my Ubuntu GNOME machine. Wanting it back had me turn to the web for an answer and I found it on a Linux Mint forum; the bash shell is so pervasive in the UNIX and Linux worlds that you can look anywhere for a fix like this.

The problem centred around the .bashrc file in my home area. It does have quite a few handy custom aliases and I must have done a foolish spring clean on the file sometime. That is the only way that I can explain how the following lines got removed:

if [ -f /etc/bash_completion ]; then
. /etc/bash_completion
fi

What they do is look to see if /etc/bash_completion can be found on your system and to use it for tab-based autocompletion. With the lines not in .bashrc, it couldn’t happen. Others may replace bash_completion with bash.bashrc to got a fuller complement of features but I’ll stick with what I have for now.

Saving Windows Command Prompt & Powershell command history to a file for later useage

It’s amazing what ideas Linux gives that you wouldn’t encounter that clearly in the world of Windows. One of these is output and command line history so a script can be created. In the Windows world, this would be called a batch file. Linux usefully has the history command and it does the needful for taking a snapshot like so:

history > ~/commands.sh

All of the commands stored in a terminal’s command history get stored in the commands.sh in the user’s home area. The command for doing the same thing from the Windows command line is not as obvious because it uses the doskey command that is intended for command line macro writing and execution. Usefully, it has a history option that tells it to output all the commands issued in a command line session. Unless, you create a file with them in there, there seems to be no way to store all those commands across sessions, unlike UNIX and Linux. Therefore, a command like the following is a partial solution that is more permanent than using the F7 key on your keyboard:

doskey /history > c:\commands.bat

Windows Powershell has something similar too and it even has aliases of history and even h. All Powershell scripts have file extensions of ps1 and the example below follows that scheme:

get-history > c:\commands.ps1

However, I believe that even Powershell doesn’t carry over command history between sessions though Microsoft are working on adding this useful functionality. They could co-opt Cygwin of course but that doesn’t seem to be their way of going about things.

Installing the Cinnamon Desktop Environment on Sabayon Linux

During the week, I did an update on my Sabayon system and GNOME 3.6 came on board without to much of a bother. There was no system meltdown or need for an operating system re-installation. However, there was one matter that rankled: adding and updating extensions from extensions. gnome.org was impossible. The process would create a new folder in ~/.local/share/gnome-shell/extensions/  but not fill it with anything at all. Populating from another my Ubuntu GNOME Remix 12.10 machine didn’t seem to achieve the needful and I am left wondering if it is down to the version of GNOME Shell being 3.6.2. However, even adding an entry for the current version of GNOME Shell to metadata.json for one plugin didn’t appear to do what I wanted so resolving this issue needs further enquiry.

In the meantime, I added the Cinnamon desktop environment using the following command and will be using that from now on. If the GNOME Shell extension issue ever gets sorted I may move back but there is no rush. GNOME 3.8 sounds like it’s bringing an interesting option that makes use of the approach Linux Mint took for version 12 of that distribution and I can await that, especially if it avoids the need for adding extension on a personal basis like now.

sudo equo update && sudo equo install cinnamon

With the installation completed by the above command, it was a matter of logging out and choosing the Cinnamon entry (there is a 2D version too) from the session dropdown menu on the login screen to get it going. Then, it was a matter of tweaking Cinnamon to my heart’s content. Getting a two panel layout required logging out and in again as well as choosing the appropriate setting in the Cinnamon Panel options tab. Next, I decided to check on what themes are available at cinnamon.linuxmint.org before settling on Cinnamint 1.6. It all feels very comfortable apart from not having an automatically growing list of workspaces that are a default offering in GNOME Shell. That goes against the design principles of Cinnamon though so only hopes of someone making an extension that does that are left.

Changing from to Nvidia Graphics Drivers on Linux Mint Debian Edition 64-bit

One way of doing this is to go to the Nvidia website and download the latest file from the relevant page on there. Then, the next stage is to restart your PC and choose rescue mode instead of the more usual graphical option. This drops you onto a command shell that is requesting your root password. Once this is done, you can move onto the next stage of the exercise. Migrate to the directory where the *.run file is located and issuing a command similar to the following:

bash NVIDIA-Linux-x86_64-295.40.run

The above was the latest file available at the time of writing so the name may have changed by the time that you read this. If the executable asks to modify your X configuration file, I believe that the best course is to let it do that. Editing it yourself or running nvidia-xconfig are alternative approaches if you so prefer.

Proprietary Nvidia drivers are included the repositories for Linux Mint Debian Edition so that may be a better course of action since you will get updates through normal system update channels. Then, the course of action is to start by issuing the following installation comands:

sudo apt-get install module-assistant
sudo apt-get install nvidia-kernel-common
sudo apt-get install nvidia-glx
sudo apt-get install kernel-source-NVIDIA
sudo apt-get install nvidia-xconfig

Once those have completed, issuing the following in turn will complete the job ahead of a reboot:

sudo m-a a-i nvidia
sudo modprobe nvidia
sudo nvidia-xconfig

If you reboot before running the above like I did, you will get a black screen with a flashing cursor instead of a full desktop because X failed to load. Then, the remedy is to reboot the machine and choose the rescue mode option, provide the root password and issue the three commands (at this point, the sudo prefix can be dropped because it’s unneeded) then. Another reboot will see order restored and the new driver in place. Running the following at that point will do a check on things as will be the general appearance of everything:

glxinfo | grep render

Getting Gnome Shell going for Fedora 16 running in VirtualBox

There are a number of complaints out there about how hard it is to get GNOME Shell running for a Fedora 16 installation in a VirtualBox virtual machine. As with earlier versions of Fedora, preparation remains a matter of having make, gcc and kernel-devel (kernel headers, in other words). While I have got away with just those, adding dkms (dynamic kernel module support) to the list might be no bad idea either. To get all of those instated, it is a matter of running the following command as root or using sudo:

yum -y install make gcc kernel-devel dkms

The -y switch ensures that any Y/N prompts that usually appear are suppressed and that the installation is completed. Just leave it out if you are inclined to get second thoughts. Another item that has been needed with a previous release of Fedora is libgomp but I haven’t had to add this for Fedora 16 if I remember correctly.

Once those are in place, it is time to install the VirtualBox Guest Additions.  Going to Devices > Install Guest Additions… mounts a virtual CD that can be used for the installation of the various drivers that are needed. To do the installation, first go to where the installer is located using the following command:

cd /media/VBOXADDITIONS_4.1.6_74713/

Note that this location will change according to the release and build numbers of VirtualBox but the process essentially will be the same other than this. Once in there, issue the following command as root or using sudo:

./VBoxLinuxAdditions.run

Hopefully, this will complete without errors now with the precursor software that has been added beforehand. However, there is one more thing that needs doing or you will get the GNOME 3 fallback desktop instead. It pertains to SELinux, an old adversary of mine that got in the way when I was setting up a web server on a machine running Fedora. It doesn’t recognise the new VirtualBox drivers as it should so the following command needs executing as root or using sudo:

restorecon -R -v /opt

Doing this restores the SELinux contexts for the /opt directories within which the VirtualBox software directories are found. The -R switch tells it to act recursively and -v makes it verbose. When it has done its work, hopefully successfully, it is time to reboot the virtual machine and you should have a GNOME Shell desktop interface when you log in.

Adding GNOME 3 to Linux Mint 11

On the surface of it, this probably sounds a very strange thing to do: choose Linux Mint because they plan to stick with their current desktop interface for the foreseeable future and then stick a brand new one on there. However, that’s what last weekend’s dalliance with Fedora 15 caused. Not only did I find that I could find my way around GNOME Shell but I actually got to like it so much that I missed it on returning to using my Linux Mint machine again.

The result was that I started to look on the web to see if there was anyone else like me who had got the same brainwave. In fact, it was Mint’s being based on Ubuntu that allowed me to get GNOME 3 on there. The task could be summarised as involving three main stages: getting GNOME 3 installed, adding extensions and adding the Cantarell font that is used by default. After these steps, I gained a well-running GNOME 3 desktop running on Linux Mint and it looks set to stay that way unless something untoward has yet to emerge.

Installing GNOME 3

The first step is to add the PPA repository for GNOME 3 using the following command:

sudo add-apt-repository ppa:gnome3-team/gnome3

The, it was a case of issuing my usual update/upgrade command:

sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade

When that had done its thing and downloaded and installed quite a few upgrades along the way, it was time to add GNOME Shell using this command:

sudo apt-get install gnome-shell

When that was done, I rebooted my system to be greeted by a login screen very reminiscent of what I had seen in Fedora. While compiling this piece, I noticed that GNOME Session could need to be added before GNOME Shell but I do not recall doing so myself. Maybe dependency resolution kept any problems at bay, but there weren’t any issues that I could remember beyond things not being configured as fully as I would have liked without further work. For the sake of safety, it might be a good idea to run the following before adding GNOME Shell to your PC.

sudo apt-get install gnome-session && sudo apt-get dist-upgrade

Configuration and Customisation

Once I had logged in, the desktop that I saw wasn’t at all unlike the Fedora one and everything seemed stable too. However, there was still work to do before I was truly at home with it. One thing that was needed was the ever useful GNOME Tweak Tool. This came in very handy for changing the theme that was on display to the standard Adwaita one that caught my eye while I was using Fedora 15. Adding buttons to application title bars for minimising and maximising their windows was another job that the tool allowed me to do. The command to get this goodness added in the first place is this:

sudo apt-get install gnome-tweak-tool

The next thing that I wanted to do was add some extensions so I added a repository from which to do this using the command below. Downloading them via Git and compiling them just wasn’t working for me so I needed another approach.

sudo add-apt-repository ppa:ricotz/testing

With that is place, I issued the following commands to gain the Dock, the Alternative Status Menu and the Windows Navigator. The second of these would have added a shutdown option in the me-menu but it seems to have got deactivated after a system update. Holding down the ALT key to change the Suspend entry to Power off… will have to do me for now. Having the dock is the most important and that, thankfully, is staying the course and works exactly as it does for Fedora.

sudo apt-get install gnome-shell-extensions-dock
sudo apt-get install gnome-shell-extensions-alternative-status-menu
sudo apt-get install gnome-shell-extensions-windows-navigator

Adding Cantarell

The default font used by GNOME 3 in various parts of its interface is Cantarell and it was defaulting to that standard sans-serif font on my system because this wasn’t in place. That font didn’t look too well so I set to tracking the freely available Cantarell down on the web.  When that search brought me to Font Squirrel, I downloaded the zip file containing the required TTF files. The next step was to install them and, towards that end, I added Fontmatrix using this command:

sudo apt-get install fontmatrix

That gave me a tool with a nice user interface but I made a mistake when using it. This was because I (wrongly) thought that it would copy files from the folder that I told the import function to use. Extracting the TTF files to /tmp meant that would have had to happen, but Fontmatrix just registered them instead. A reboot confirmed that they hadn’t been copied or moved at all and I had rendered the user interface next to unusable through my own folly; the default action on Ubuntu and Linux Mint is that files are deleted from /tmp on shutdown. The font selection capabilities of the GNOME Tweak Tool came in very handy for helping me to convert useless boxes into letters that I could read.

Another step was to change the font line near the top of the GNOME Shell stylesheet (never thought that CSS usage would end up in places like this…) so that Cantarell wasn’t being sought and text in sans-serif font replaced grey and white boxes. The stylesheet needs to be edited as superuser, so the following command is what’s needed for this and, while I used sudo, gksu is just as useful here if it isn’t what I should have been using.

sudo gedit /usr/share/gnome-shell/theme/gnome-shell.css

Once I had extricated my system from that mess, a more conventional approach was taken and the command sequence below was what I followed, with extensive use of sudo to get done what I wanted. A new directory was created and the TTF files copied in there.

cd /usr/share/fonts/truetype
sudo mkdir ttf-cantarell
cd ttf-cantarell
sudo mv /tmp/*.ttf .

To refresh the font cache, I resorted to the command described in a tutorial in the Ubuntu Wiki:

sudo fc-cache -f -v

Once that was done, it was then time to restore the reference to Cantarell in the GNOME Shell stylesheet and reinstate its usage in application windows using the GNOME Tweak Tool. Since then, I have suffered no mishap or system issue with GNOME 3. Everything seems to be working quietly and I am happy to see that replacement of Unity with the GNOME Shell will become an easier task in Ubuntu 11.10, the first alpha release of which is out at the time of my writing these words. Could it lure me back from my modified instance of Linux Mint yet? While I cannot say that I am sure of those but it certainly cannot be ruled out at this stage.

GNOME 3 in Fedora 15: A Case of Acclimatisation and Configuration

When I gave the beta version of the now finally released Fedora 15 a try, GNOME 3 left me thinking that it was even more dramatic and less desirable a change than Ubuntu’s Unity desktop interface. In fact, I was left with serious questions about its actual usability, even for someone like me. It all felt as if everything was one click further away from me and thoughts of what this could mean for anyone seriously afflicted by RSI started to surface in my mind, especially with big screens like my 24″ Iiyama being commonplace these days. Another missing item was somewhere on the desktop interface for shutting down or restarting a PC; it seemed to be a case of first logging off and then shutting down from the login screen. This was yet another case of adding to the number of steps for doing something between GNOME 2 and GNOME 3 with its GNOME Shell.

After that less than positive experience with a Live CD, you’d be forgiven for thinking that I’d be giving the GNOME edition of Fedora 15 a wide berth with the LXDE one being chosen in its place. Another alternative approach would have been to turn off GNOME Shell altogether by forcing the fallback mode to run all the time. The way to do this is start up the System Settings application and click on the System Info icon. Once in there, click on Graphics and turn on the Forced Fallback Mode option. With that done, closing down the application, logging off and then back on again will gain you an environment not dissimilar to the GNOME 2 of Fedora 14 and its forbears.

Even after considering the above easy way to get away from and maybe even avoid the world of GNOME Shell, I still decided to give it another go to see if I could make it work in a way that was less alien to me. After looking at the handy Quickstart guide, I ventured into the world of GNOME Shell extensions and very useful these have come to be too. The first of these that I added was the Alternate Status Menu and I ran the following command to do so:

yum install gnome-shell-extensions-alternative-status-menu

The result was that the “me” menu gained the ever useful “Power Off…” entry that I was seeking once I refreshed the desktop by running the command r in the command entry box produced by the ALT + F2 keyboard combination. Next up was the Place Menu and the command used to add that is:

yum install gnome-shell-extensions-place-menu

Again, refreshing the desktop as described for the Alternate Status Menu added the new menu to the (top) panel. Not having an application dock on screen all the time was the next irritation that was obliterated and it helps to get around the lack of a workspace switcher for now too. The GNOME Shell approach to virtual desktops is to have a dynamic number of workspaces with there always being one more than what you are using. It’s an interesting way of working that doesn’t perturb more pragmatic users like me, but there are those accustomed to tying applications to particular workspaces aren’t so impressed by the change. The other change to workspace handling is that keyboard shortcuts have changed to CTRL-ALT-[Up Arrow] and CTRL-ALT-[Down Arrow] from CTRL-ALT-[Left Arrow] and CTRL-ALT-[Right Arrow].

To add that application dock, I issued the command below and refreshed the desktop to get it showing. Though it stops application windows becoming fully maximised on the screen, that’s not a problem with my widescreen monitor. In fact, it even helps to switch between workspaces using the keyboard because that doesn’t seem to work when you have fully maximised windows.

yum install gnome-shell-extensions-dock

After adding the application dock, I stopped adding extensions though there are more available, such as Alternate Tab Behaviour (restores the ALT-TAB behaviour of GNOME 2), Auto-Move Windows, Drive Menu, Native Window Placement, Theme Selector and Window Navigator. Here are the YUM commands for each of these in turn:

yum install gnome-shell-extensions-alternate-tab
yum install gnome-shell-extensions-auto-move-windows
yum install gnome-shell-extensions-drive-menu
yum install gnome-shell-extensions-native-window-placement
yum install gnome-shell-extensions-theme-selector
yum install gnome-shell-extensions-user-theme
yum install gnome-shell-extensions-windowsNavigator

One hope that I will retain is that more of these extensions will appear over time, but Ranjith Siji seems to have a good round up of what is available. Other than these, I also have added the DCONF Editor and GNOME Tweaks Tool with the latter restoring buttons for minimising and maximising windows to their title bars for me. As ever, YUM was called to add them using the following commands:

yum install dconf-editor
yum install gnome-tweaks-tool

There are other things that can be done with these but I haven’t explored them yet. All YUM commands were run as root and the ones that I used certainly have helped me to make myself at home in what once was a very unfamiliar desktop environment for me. In fact, I am beginning to like what has been done with GNOME 3 though I have doubts as to how attractive it would be to a user coming to Linux from the world of Windows. While everything is solidly crafted, the fact that I needed to make some customisations of my own raises questions about how suitable the default GNOME set-up in Fedora is for a new user though Fedora probably isn’t intended for that user group anyway. Things get more interesting when you consider distros favouring new and less technical users, both of whom need to be served anyway.

Ubuntu has gone its own way with Unity and, having spent time with GNOME 3, I can see why they might have done that. Unity does put a lot more near at hand on the desktop than is the case with GNOME 3 where you find yourself going to the Activities window a lot, either by using your mouse or by keystrokes like the “super” (or Windows) key or ALT-F1. Even so, there are common touches like searching for an application like you would search for a web page in Firefox. In retrospect, it is a pity to see the divergence when something from both camps might have helped for a better user experience. Nevertheless, I am reaching the conclusion that the Unity approach feels like a compromise and that GNOME feels that little bit more polished. Saying that, an extra extension or two to put more items nearer to hand in GNOME Shell would be desirable. If I hadn’t found a haven like Linux Mint where big interface changes are avoided, maybe going with the new GNOME desktop mightn’t have been a bad thing to do after all.

Using Data Step to Create a Dataset Template from a Dataset in SAS

Recently, I wanted to make sure that some temporary datasets that were being created during data processing in a dataset creation program weren’t truncating values or differed from the variable lengths in the original. It was then that a brainwave struck me: create an empty dataset shell using data step and use that set all the variable lengths for me when the new datasets were concatenated to it. The code turned out to be very simple and here is an example of how it looked:

data shell;
stop;
set example;
run;

The STOP statement, prevents the data step from reading in any of the values in the template dataset and just its header is written out to another (empty) dataset that can be used to set things up as you would want them to be. It certainly was a quick solution in my case.

Shell swapping in Windows

Until the advent of PowerShell, Windows had been the poor relation when it came to working from the command line when compared with UNIX, Linux and so on. A recent bit of fiddling had me trying to run FTP from the legacy command prompt when I ran into problems with UNC address resolution (it’s unsupported by the old technology) and mapping of network drives. It turned out that my error 85 was being caused by an unavailable drive letter that the net use command didn’t reveal as being in use. Reassuringly, this wasn’t a Vista issue that I couldn’t circumvent.

During this spot of debugging, I tried running batch files in PowerShell and discovered that you cannot run them there like you would from the old command prompt. In fact, you need a line like the following:

cmd /c script.bat

In other words, you have to call cmd.exe like perl.exe, wscript.exe and cscript.exe for batch files to execute. If I had time, I might have got to exploring the use ps1 files for setting up PowerShell commandlets but that is something that needs to wait until another time. What I discovered though is that UNC addressing can be used with PowerShell without the need for drive letter mappings, not a bad development at all. While on the subject of discoveries, I discovered that the following command opens up a command prompt shell from PowerShell without any need to resort to the Start Menu:

cmd /k

Entering the exit command returns you to the PowerShell command line again and entering cmd /? reveals the available options for the command so you need never be constrained by your own knowledge or its limitations.

ImageMagick and Ubuntu 9.04

Using a command line tool like ImageMagick for image processing may sound a really counter-intuitive thing to do but there’s no need to do everything on a case by case interactive basis. Image resizing and format conversion come to mind here. Helper programs are used behind the scenes too with Ghostscript being used to create Postscript files, for example.

The subject of helper programs brings me to an issue that has hampered me recently. While I am aware that there are tools like F-Spot available, I am also wont to use a combination of shell scripting (BASH & KSH), Perl and ImageMagick for organising my digital photos. My preference for using Raw camera files (DNG & CRW) means that ImageMagick cannot access these without a little helper. In the case of Ubuntu, it’s UFRaw. However, Jaunty Jackalope appears to have seen UFRaw updated to a version that is incompatible with the included version of ImageMagick (6.4.5 as opposed to 3.5.2 at the time of writing). The result is that the command issued by ImageMagick to UFRaw -- issue the command man ufraw-batch to see the details -- is not accepted by the included version of the latter, 0.15 if you’re interested. It seems that an older release of UFRaw accepted the output device ppm16 (16-bit PPM files) but this should now be specified as ppm for the output device and 16 for the output depth. In a nutshell, where the parameter output-type did the lot, you now need both output-type and output-depth.

I thought of decoupling things by using UFRaw to create 16-bit PPM files for processing by ImageMagick but to no avail. The identify command wouldn’t return the date on which the image was taken. I even changed the type to 8-bit JPEG’s with added EXIF information but no progress was made. In the end, a mad plan came to mind: creating a VirtualBox VM running Debian. The logic was that if Debian deserves its reputation for solidity, dependencies like ImageMagick and UFRaw shouldn’t be broken and I wasn’t wrong. To make it fly though, I needed to see if I could get Guest Additions installed on Debian. Out of the box, the supported kernel version must be at least 2.6.27 and Debian’s is 2.6.26 so additional work was on the cards. First, GCC, Make and the correct kernel header files need to be installed. Once those are in place, the installation works smoothly and a restart sets the goodies in motion. To make the necessary Shared folder to be available, a command like the following was executed:

mount -t vboxfs [Shared Folder name] [mount point]

Once that deed was done and ImageMagick instated, the processing that I have been doing for new DSLR images was reinstated. Ironically, Debian’s version of ImageMagick, 6.3.7, is even older than Ubuntu’s but it works and that’s the main thing. There is an Ubuntu bug report for this on Launchpad so I hope that it gets fixed at some point in the near future. However, that may mean awaiting 9.10 or Karmic Koala so I’m glad to have the workaround in the meantime.