Technology Tales

Adventures in consumer and enterprise technology

TOPIC: LINUX

Sorting a kernel upgrade error in Linux Mint 13

30th November 2012

Linux Mint 14 may be out now, but I'll be sticking with its predecessor for now. Being a user of GNOME Shell instead of Cinnamon or Mate, I'll wait for extensions to get updated for 3.6 before making a move away from 3.4 where the ones that I use happily work. Given that Linux Mint 13 is set to get support until 2017, it's not as if there is any rush either. Adding the back-ported packages repository to my list of software sources means that I will not miss out on the latest versions of MDM, Cinnamon and Mate anyway. With Ubuntu set to stick to GNOME 3.6 until after 13.04 is released, adding the GNOME 3 Team PPA will be needed if 3.8 arrives with interesting goodies; there are interesting noises that suggest the approach taken in Linux Mint 12 may be used to give more of a GNOME 2 desktop experience. Options abound and there are developments in the pipeline that I hope to explore too.

However, there is one issue that I have had to fix which stymies upgrades within the 3.2 kernel branch. A configuration file (/etc/grub.d/10_linux) points to /usr/share/grub/grub-mkconfig_lib instead of /usr/lib/grub/grub-mkconfig_lib so I have been amending it every time I needed to do a kernel update. However, it just reverts to the previous state, so I thought of another solution: creating a symbolic link in the incorrect location that points to the correct one so that updates complete without manual intervention every time. The command that does the needful is below:

sudo ln -s /usr/lib/grub/grub-mkconfig_lib /usr/share/grub/grub-mkconfig_lib

Of course, figuring out what causes the reversion would be good too, but the symbolic link fix works so well that there's little point in exploring it further. Of course, if anyone can add how you'd do that, I'd welcome this advice too. New knowledge is always good.

A place for GNOME?

21st September 2012

There has been a lot of doom and gloom spoken about the GNOME desktop environment and the project behind it. These days, it seems to be the fashionable thing to go constantly criticising it, especially after what Linus Torvalds said. KDE went through the same sort of experience a few years ago and seems to have got far enough beyond it that some are choosing it instead of GNOME. For a good while, it was the other way around.

Since its inception, the GNOME Shell has attracted a lot of adverse comment. However, since my first encounter, it has grown on me to the point that I added it to Ubuntu and Linux Mint and use it as my default desktop environment instead of Unity, Mate or Cinnamon. The first of these may not be so surprising because of the unique approach that has been taken. The use of lenses and an application launch bar are items to which I could adapt, but it is the merging of application menus and title bars with the top panel of the desktop that really puts me off it. Application window buttons can be moved to the right everywhere but on this global menu, so I tend to view things from afar instead of using it every day. There just is something about the experience that won't grow on me. Strangely, that also applies to my impressions of KDE, albeit differently; there just is something less slick about the appearance of the bottom panel, the plasmoids and other items like them.

Given that Mate and Cinnamon continue the GNOME 2 approach to things that dominated my home computing for much of the last five years since I turned to Ubuntu, my decision to use GNOME Shell instead of either come as a surprise. It isn't that the environments aren't slick enough, just that I have come to prefer the way that GNOME Shell handles workspaces, spawning them as you need them. If that could be an option in Cinnamon, then it might become my desktop of choice. However, that seems to go against the philosophy of the project, even if someone adds and extension for it.

For a time, I played with going with LXDE rather than either Unity or GNOME Shell; as it happened, my first impressions of the latter weren't so positive until I spent a day with the GNOME variant of Fedora 15. Being not dissimilar to GNOME 2 in the way that it worked was the main attraction of LXDE and my initial use of it was with Lubuntu running on a netbook; the LXDE version of Linux Mint 12 now runs on it so there hasn't been so much change on that machine.

Sometimes, the only way to deal with change is to have a look at it to see what's coming and to decide what you need to do about it. In the case of GNOME Shell, my day with Fedora 15 on a backup PC changed my impressions, and Linux Mint 11's GNOME 2 desktop looked a bit old-fashioned afterwards. In fact, I popped GNOME 3 on there and have been using it as my main desktop environment ever since.

With computing, there always are some who expect things to just work and be the way that they want them. The need for extra configuration is a criticism that still can be levelled at GNOME Shell. Before going with Mate and Cinnamon, Linux Mint went the same way for a while, leaving me to wonder what can be done with such an approach. Will someone else pick up that baton and do the handiwork so that users don't have to do it? Not yet, it seems. Since no one is following the lead of Linux Mint 12, the need for user tweaking remains, even if I have found which ones work for me.

The first place to begin is GNOME's Extensions website, from where I raid a few extensions every time I do an operating system installation. The Alternative Status Menu extension is among the first to get added so that I have the shutdown option again on the user menu, a common criticism of the default set up. Since I always install the GNOME Tweak Tool from the distro repositories, I add the Advanced Setting in User Menu extension to get an entry in the status menu that grants quick access. Frippery Bottom Panel comes next on the list because of its workspace switcher and application window list. Others like Frippery Move Clock, Monitor Status Indicator, Places Status Indicator, Removable Drive Menu, Remove Accessibility, Shell Restart User Menu Entry and User Themes follow in some order and make things feel more pleasing, at least to my mind.

You aren't stuck with the default theme, either, and I have chosen Elementary Luna from deviantART. For adding your own themes, the above listed User Themes extension is needed. Because I want the Frippery Bottom Panel to match the top panel, I tweaked its stylesheet and that's where the Restart User Menu Entry extension comes in handy, though some care is needed not to crash the desktop with constant shell restarts.

Doing the above makes GNOME Shell really amenable to me, and I wouldn't like to lose that freedom to customise. Saying that, the continued controversial changes aren't stopping yet. Those made to the Nautilus file manager in GNOME 3.6 have caused the Linux Mint project to create Nemo, a fork of the software, and Ubuntu is sticking with the previous version for now. Taking some action yourself instead of just complaining loudly sounds like a more positive approach, which makes its own statement. However, at a time when many want the GNOME project team to listen to users, the new Nautilus appears and is not to be what they needed to see. Could the project go on like this? Only time can answer that one.

While it appears that many have changed from GNOME to other desktop environments, I haven't come across any numbers. A reducing user base could be a way of sending a message about any discontent, one that makes use of a great feature of free software: there is plenty of choice. If the next version of Nautilus isn't to my taste, there are plenty of alternatives out there. After all, Cinnamon started on Linux Mint and has gone from there to being available for other distros too; Fedora is one example. Nemo could follow suit.

Now that GNOME's constituent applications are seeing changes, GNOME Shell may be left to mature. Computer interfaces are undergoing a lot of change at the moment and Microsoft Windows 8 is bringing its own big leap. Though controversial at the time, change can be a good thing too and us technical folk always like seeing new things come along (today saw the launch of the iPhone 5 and many folk queueing up for it; Google's Nexus 7 ran out of stock in its first weeks on the market; there are more). That could be what got me using GNOME 3 in the first place, even if my plan is to stick with it for a while yet.

Removing VMware Player from Linux Mint Debian Edition

4th August 2012

A whole slew of updates has appeared for my Linux Mint Debian Edition PC. However, to instate them, I needed to remove VMware Player and this is the command to do so:

sudo vmware-installer -u vmware-player

It worked in my case, and my system updates are in progress as I write this. The same command should work for other Linux distros where VMware Player was installed using the *.bundle installer. VMware Player remains in place on my main PC though, so I am not ditching it just yet, even if I have to be careful when running it on Linux Mint 13 so as not to freeze the system on myself.

Synchronising package selections between Linux Mint and Linux Mint Debian Edition

18th April 2012

To generate the package list on the GNOME version of Linux Mint, I used the Backup Tool. It simply was a matter of using the Backup Software Selection button and telling it where to put the file that it generates. Alternatively, dpkg can be used from the command line like this:

sudo dpkg --get-selections > /backup/installed-software.txt

After transferring the file to the machine with Linux Mint Debian Edition, I tried using the Backup Tool on there too. However, using the Restore Software Selection button and loading the required only produced an irrecoverable error. Therefore, I set to looking around the web and found a command line approach that did the job for me.

The first step is to load the software selection using dpkg by issuing this command (it didn't matter that the file wasn't made using the dpkg command, though I suspect that's what the Linux Mint Backup Tool was doing that behind the scenes):

sudo dpkg --set-selections < /backup/installed-software.txt

Then, I started dselect and chose the installation option from the menu that appeared. The first time around, it fell over but trying again was enough to complete the job. Packages available to the vanilla variant of Linux Mint but not found in the LMDE repositories were overlooked as I had hoped, and installation of the extra packages had no impact on system stability either.

sudo dselect

Apparently, there is an alternative to using dselect that is based on the much used apt-get command, but I didn't make use of it so cannot say more:

sudo apt-get dselect-upgrade

All that I can say is that the dpkg/dselect combination did what I wanted, so I'll keep them in mind if ever need to synchronise software selections between two Debian-based distributions in the future again. While the standard edition of Linux Mint may be based on Ubuntu rather than Debian, Ubuntu is itself based on Debian. Thus, the description holds here.

Uninstalling VirtualBox Guest Additions on a Linux Guest OS

8th April 2012

Within the last few days, I updated my Linux Mint Debian Edition virtual machine installation to Update 4. Between not following the instructions so closely and problems with the update server, a re-installation preceded the update itself. When all was done, no desktop environment appeared, and issuing the startx command revealed that it was one of the VirtualBox drivers that was the cause of the problem. With my being unable to see any files on the VirtualBox virtual CD, something else needed doing and the executing following command (replacing [VboxAddonsFolder] with VBoxGuestAdditions-4.1.12 in my case, but it is different for each VirtualBox version) resolved the situation:

/opt/[VboxAddonsFolder]/uninstall.sh

When it was complete, a scrambled desktop began to appear, so a reboot was to set things to rights. Then, I could set to looking at what Update 4 had brought to Linux Mint Debian Edition.

Widely differing approaches

28th January 2012

The computer on which I am writing these words is running Linux Mint with the Cinnamon desktop environment, a fork of GNOME Shell. This looks as if it will be the default face of GNOME 3 in the next version of Linux Mint, with the MGSE dressing up of GNOME Shell looking more and more like an interim measure until something more consistent was available. While some complained that what was delivered in version 12 of the distribution was a sort of greatest hits selection, I reckon that bets were being hedged by the project team.

Impressions of what's coming

By default, you get a single panel at the bottom of your screen with everything you need in there. However, it is possible to change the layout so that the panel is at the top or there are two panels, one at the top and the other at the bottom. So far, there is no means of configuring which panel applet goes where, as was the case in Linux Mint 11 and its predecessors. However, the default placements are very sensible, so I have no cause for complaint at this point.

Just because you cannot place applets doesn't mean that there is no configurability, though. Since Cinnamon is extensible, you can change the way that time is displayed in the clock, as well as enabling additional applets. It also is possible to control visual effects, such as the way new application windows pop up on a screen.

GNOME 3 is there underneath all of this, though there's no sign of the application dashboard of GNOME Shell. The continually expanding number of slots in the workspace launcher is one sign, as is the enabling of a hotspot at the top right hand corner by default. This brings up an overview screen showing what application windows are open in a workspace. The new Mint menu even gets the ability to search through installed applications, together with the ability to browse through what's available.

In summary, Cinnamon already looks good, though a little polish and extra configuration options wouldn't go amiss. An example of the former is the placement of desktop numbers in the workspace switcher, and I already have discussed the latter.  It does appear that the Linux Mint approach to desktop environments is taking shape with a far more conventional feel than the likes of Unity or GNOME Shell. Just as Cinnamon has become available in openSUSE, I can see it gracing LMDE too whenever Debian gets to moving over to GNOME 3 as must be inevitable now unless they take another approach such as MATE.

In comparison with a revolution

While Linux Mint are choosing convention and streamlining GNOME to their own designs, it appears that Ubuntu's Unity is getting ever more experimental as the time when Ubuntu simply evolved from one release to the next becomes an increasingly more distant memory. The latest development is the announcement that application menus could get replaced by a heads-up display (HUD) instead. That would be yet another change made by what increasingly looks like a top-down leadership, reminiscent of what exists at Apple. While it is good to have innovation, you have to ask where users fit in all of this when Linux Mint already has gained from what has been done so far and may gain more again. Still, seeing what happens to Ubuntu sounds like an interesting pastime, though I'm not sure that I'd be depending on the default spin of this distro as my sole operating system right now. Also, changing the interface every few months wouldn't work in a corporate environment at all, so you have to wonder where Mark Shuttleworth is driving all this, though Microsoft is engaging in a bit of experimentation of its own. We are living in interesting times for the computer desktop, so it's just as well that there are safe havens like Linux Mint, too. Watching from afar sounds safer.

Getting Gnome Shell going for Fedora 16 running in VirtualBox

5th December 2011

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 recall 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, yet the process essentially will be the same aside from 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.

An in situ upgrade to Linux Mint 12

4th December 2011

Though it isn't the recommended approach, I have ended up upgrading to Linux Mint 12 from Linux Mint 11 using an in situ route. Having attempted this before with a VirtualBox hosted installation, I am well aware of the possibility of things going wrong. Then, a full re-installation was needed to remedy the situation. With that in mind, I made a number of backups in the case of an emergency fresh installation of the latest release of Linux Mint. Apache and VirtualBox configuration files together with MySQL backups were put where they could be retrieved should that be required. The same applied to the list of installed packages on my system. So far, I haven't needed to use these, but there is no point in taking too many chances.

The first step in an in-situ Linux Mint upgrade is to edit /etc/apt/sources.list. In the repository location definitions, any reference to katya (11) was changed to lisa (for 12) and the same applied to any appearance of natty (Ubuntu 11.04) which needed to become oneiric (Ubuntu 11.10). With that done, it was time to issue the following command:

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

Once that had completed, it was time to add the new additions that come with Linux Mint 12 to my system using a combination of apt-get, aptitude and Synaptic; the process took a few cycles. GNOME already was in place from prior experimentation, so there was no need to add this anew. However, I need to instate MGSE to gain the default Linux Mint customisations of GNOME 3. Along with that, I decided to add MATE, the fork of GNOME 2. That necessitated the removal of two old libraries (libgcr0 and libgpp11, if I recall correctly, which will tell you what is causing any conflict) using Synaptic. With MGSE and MATE in place, it was time to install LightDM and its Unity greeter to get the Linux Mint login screen. Using GDM wasn't giving a very smooth visual experience and Ubuntu, the basis of Linux Mint, uses LightDM anyway. Even using the GTK greeter with LightDM produced a clunky login box in front of a garish screen. Configuration tweaks could have improved on this, but it appears that using LightDM and Unity greeter is what gives the intended setup and experience.

With all of this complete, the system seemed to be running fine until the occasional desktop freeze occurred with Banshee running. Blaming that, I changed to Rhythmbox instead, though that helped only marginally. While this might be blamed on how I upgraded my system, things seemed to have steadied themselves in the week since then. As a test, I had the music player going for a few hours and there was no problem. With the call for testing of an update to MATE a few days ago, it now looks as if there may have been bugs in the original release of Linux Mint 12. Daily updates have added new versions of MGSE and MATE, so that may have something to do with the increase in stability. Even so, I haven't discounted the possibility of needing to do a fresh installation of Linux Mint 12 just yet. However, if things continue as they are, then it won't be needed and that's an upheaval avoided should things go that way. That's why in situ upgrades are attractive, though rolling distros like Arch Linux (these words are being written on a system running this) and LMDE are more so.

Sorting out MySQL on Arch Linux

5th November 2011

Seeing Arch Linux running so solidly in a VirtualBox virtual box has me contemplating whether I should have it installed on a real PC. Saying that, recent announcements regarding the implementation of GNOME 3 in Linux Mint have caught my interest, even if the idea of using a rolling distribution as my main home operating system still has a lot of appeal for me. Having an upheaval come my way every six months when a new version of Linux Mint is released is the main cause of that.

While remaining undecided, I continue to evaluate the idea of Arch Linux acting as my main OS for day-to-day home computing. Towards that end, I have set up a working web server instance on there using the usual combination of Apache, Perl, PHP and MySQL. Of these, it was MySQL that went the least smoothly of all because the daemon wouldn't start for me.

It was then that I started to turn to Google for inspiration, and a range of actions resulted that combined to give the result that I wanted. One problem was a lack of disk space caused by months of software upgrades. Since tools like it in other Linux distros allow you to clear some disk space of obsolete installation files, I decided to see if it was possible to do the same with pacman, the Arch Linux command line package manager. The following command, executed as root, cleared about 2 GB of cruft for me:

pacman -Sc

The S in the switch tells pacman to perform package database synchronization, while the c instructs it to clear its cache of obsolete packages. In fact, using the following command as root every time an update is performed both updates software and removes redundant or outmoded packages:

pacman -Syuc

So I don't forget the needful housekeeping, this will be what I use from this point forward, with y being the switch for a refresh and u triggering a system upgrade. It's nice to have everything happen together without too much effort.

To do the required debugging that led me to the above along with other things, I issued the following command:

mysqld_safe --datadir=/var/lib/mysql/ &

This starts up the MySQL daemon in safe mode if all is working properly, and it wasn't in my case. Nevertheless, it creates a useful log file called myhost.err in /var/lib/mysql/. This gave me the messages that allowed the debugging of what was happening. It led me to installing net-tools and inettools using pacman; it was the latter of these that put hostname on my system and got the MySQL server startup a little further along. Other actions included unlocking the ibdata1 data file and removing the ib_logfile0 and ib_logfile1 files to gain something of a clean sheet. The kill command was used to shut down any lingering mysqld sessions too. To ensure that the ibdata1 file was unlocked, I executed the following commands:

mv ibdata1 ibdata1.bad
cp -a ibdata1.bad ibdata1

These renamed the original and then crafted a new duplicate of it, with the -a switch on the cp command forcing copying with greater integrity than normal. Along with the various file operations, I also created a link to my.cnf, the MySQL configuration file on Linux systems, in /etc using the following command executed by root:

ln -s /etc/mysql/ my.cnf /etc/my.cnf

While I am unsure if this made a real difference, uncommenting the lines in the same file that pertained to InnoDB tables. What directed me to these were complaints from mysqld_safe in the myhost.err log file. All I did was to uncomment the lines beginning with innodb and these were 116-118, 121-122 and 124-127 in my configuration file, but it may be different in yours.

After all the above, the MySQL daemon ran happily and, more importantly, started when I rebooted the virtual machine. Thinking about it now, I believe that it was a lack of disk space, the locking of a data file and the lack of InnoDB support that was stopping the MySQL service from running. Running commands like mysqld start weren't yielding useful messages, so a lot of digging was needed to get the result that I needed. In fact, that's one of the reasons why I am sharing my experiences here.

In the end, creating databases and loading them with data were all that was needed for me to start to see functioning websites on my (virtual) Arch Linux system. It turned out to be another step on the way to making it workable as a potential replacement for the Linux distributions that I use most often (Linux Mint, Fedora and Ubuntu).

All Change?

19th September 2011

Could 2011 be remembered as the year when the desktop computing interface got a major overhaul? One part of this, Windows 8, won't be with us until next year, but there has been enough happening so far this year that has resulted in a lot of comment. With many if not all the changes, it is possible to detect the influence of interfaces used on smartphones. After all, the carry-over from Windows Phone 7 to the new Metro interface is unmistakeable.

Two developments in the Linux world have spawned a hell of an amount of comment: Canonical's decision to develop Unity for Ubuntu and the arrival of GNOME 3. While there have been many complaints about the changes made in both, there must be a fair few folk who are just getting on with using them without complaint. Maybe there are many who even quietly like the new interfaces. While I am not so sure about Unity, I surprised myself by taking to GNOME Shell so much that I installed it on Linux Mint. It remains a work in progress, as does Unity, but it'll be very interesting to see it mature. Perhaps a good number of the growing collection of GNOME Shell plugins could make it into the main codebase. If that were to happen, I could see it being welcomed by a good few folk.

There was little doubt that the changes in GNOME 3 looked daunting, so Ubuntu's taking a different approach is understandable until you come to realise how change that involves anyway. With GNOME 3 working so well for me, I feel disinclined to dally very much with Unity at all. In fact, I am writing these words on a Toshiba laptop running UGR, effectively Ubuntu running GNOME 3, and that could become my main home computing operating system in time.

For those who find these changes not to their taste, there are alternatives. Some Linux distributions are sticking with GNOME 2 as long as they can, and there apparently has been some mention of a fork to keep a GNOME 2 interface available indefinitely. However, there are other possibilities such as LXDE and XFCE out there too. In fact, until GNOME 3 won me over, LXDE was coming to mind as a place of safety until I learned that Linux Mint was retaining its desktop identity. As always, there's KDE too, but I have never warmed to that for some reason.

The latest version of OS X, Lion, also included some changes inspired by iOS, the operating system that powers both the iPhone and iPad. However, while the current edition of PC Pro highlights some disgruntlement in professional circles regarding Apple's direction, this does not seem to have aroused the kind of ire that has been abroad in the world of Linux. Is it because Linux users want to feel that they are in charge and that iMac and MacBook users are content to have decisions made for them so long as everything just works? Speaking for myself, the former description seems to fit me, though having choices means that I can reject decisions that I do not like so much.

At the time of writing, the release of a developer preview of the next version of Windows has been generating a lot of attention. It also appears that changes are headed for Windows users too. However, I get the sense that a more conservative interface option will be retained and that could be essential for avoiding the alienation of corporate users. After all, I cannot see the Metro interface gaining much favour in the working environment when so many of us have so much to do. Nevertheless, I plan to get my hands on the developer preview to have a look (the weekend proved too short for this). It will be very interesting to see how the next version of Windows develops, and I plan to keep an eye on it as it does so.

It now looks as if many will have their work cut out if they are to avoid where desktop computing interfaces are going. Established paradigms are being questioned, particularly as a result of touch interfaces on smartphones and tablets. Wii and Kinect have involved other ways of interacting with computers, too, so there's a lot of mileage in rethinking how we work with computers. So far, I have been able to deal with the changes in the world of Linux, but I am left wondering about the changes that Microsoft is making. After Vista, they need to be careful and they know that. Maybe, they'll be better at getting users through changes in computing interfaces than others, but it'll be very interesting to see what happens. Unlike open source community projects, they have the survival of a massive multinational at stake.

  • The content, images, and materials on this website are protected by copyright law and may not be reproduced, distributed, transmitted, displayed, or published in any form without the prior written permission of the copyright holder. All trademarks, logos, and brand names mentioned on this website are the property of their respective owners. Unauthorised use or duplication of these materials may violate copyright, trademark and other applicable laws, and could result in criminal or civil penalties.

  • All comments on this website are moderated and should contribute meaningfully to the discussion. We welcome diverse viewpoints expressed respectfully, but reserve the right to remove any comments containing hate speech, profanity, personal attacks, spam, promotional content or other inappropriate material without notice. Please note that comment moderation may take up to 24 hours, and that repeatedly violating these guidelines may result in being banned from future participation.

  • By submitting a comment, you grant us the right to publish and edit it as needed, whilst retaining your ownership of the content. Your email address will never be published or shared, though it is required for moderation purposes.