Adventures & experiences in contemporary technology
There are times when blogs cease to exist and the only place to find the content is on the Wayback Machine. Even then, it is in danger of being lost completely. One such example is the subject of this post.
Though this website makes use of the facilities of Cloudflare for various functions that include the blocking of image hotlinking, the same outcome can be achieved using .htaccess files on Apache web servers. It may work on Nginx to a point too but there are other configuration files that ought to be updated instead of using a .htaccess when some frown upon the approach. In any case, the lines that need adding to .htaccess are listed below though the web address needs to include your own domain in place of the dummy example provided:
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?yourdomain.com(/)?.*$ [NC]
RewriteRule .*\.(gif|jpe?g|png|bmp)$ [F,NC]
The first line turns on the mod_rewrite engine and you may have that done anyway. Of course, the module needs enabling in your Apache configuration for this to work and you have to be allowed to perform the required action as well. This means changing the Apache configuration files. The next pair of lines look at the HTTP referer strings and the third one only allows images to be served from your own web domain and not others. To add more, you need to copy the third line and change the web address accordingly. Any new lines need to precede the last line that defines the file extensions that are to be blocked to other web addresses.
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?yourdomain.com(/)?.*$ [NC]
RewriteRule \.(gif|jpe?g|png|bmp)$ /images/image.gif [L,NC]
Another variant of the previous code involves changing the last line to display a default image showing others what is happening. That may not reduce the bandwidth usage as much as complete blocking but it may be useful for telling others what is happening.
A few years back, I came across a very nice article discussing how you would make a dynamic URL more palatable to a search engine and I made good use of its content for my online photo gallery. The premise was that URL’s that look like that below are no help to search engines indexing a website. Though this is received wisdom in some quarters, it doesn’t seem to have done much to stall the rise of WordPress as a blogging platform.
http://www.mywebsite.com/serversidescript.php?id=394
That said, WordPress does offer a friendlier URL display option too and you can see this in use on this blog; they look a little like the example URL that you see below, and the approach is equally valid for both Perl and PHP. I have been using the same approach for the Perl scripts powering my online phone gallery and now want to apply the same thinking to a gallery written in PHP:
http://www.mywebsite.com/serversidescript.pl/id/394
The way that both expressions work is that a web server will chop pieces from a URL until it reaches a physical file. For a query URL, the extra information after the question mark is retained in its QUERY_STRING variable while extraneous directory path information is passed in the variable PATH_INFO. For both Perl and PHP, these are extracted from the entries in an array; for Perl, this array is called is $ENV and $_SERVER is the PHP equivalent. Thus, $ENV{QUERY_STRING} and $_SERVER{‘QUERY_STRING’} traps what comes after the “?” while $ENV{PATH_INFO} and $_SERVER{‘PATH_INFO’} picks up the extra information following the file name (the “/id/394/” in the example). From there on, the usual rules apply regarding cleaning of any input but changing from one to another should be too arduous.
Ubuntu users must be spoilt because any MySQL installation asks you for a rootĀ password, a very good thing in my opinion. With Fedora, it just pops the thing on there with you needing to set up a service and setting the root password yourself; if I remember correctly, I think that openSUSE does the same thing. For the service management, I needed to grab system-config-services from the repositories because my Live CD installation left off a lot of stuff, OpenOffice and GIMPĀ even. The following command line recipe addressed the service managerĀ omission:
su -- # Change to root, entering password when asked
yum -yĀ install system-config-services # Installs the thing without a yes/no prompt
exit # Return to normal user shell
Thereafter, the Services item from the menus at System > Administration was pressedĀ into service and the MySQL service enabled and started. The next step was to lock down rootĀ so the following sequence was used:
mysqlĀ # Enter MySQL prompt; no need for user or password because it still is unsecured!
UPDATE mysql.user SET Password=PASSWORD(‘MyNewPass’) WHERE User=’root’;
FLUSH PRIVILEGES;
quit # Exit the mysqlĀ prompt, leaving the bare mysql command unusable
For those occasions when password problems keep you of the MySQL shell, you’ll find password resetting adviceĀ on the MySQL website but I didn’t need to go the wholeĀ hog here. MySQL Administrator might be another option for this type of thing. That thought never struck me while I was using it to set up less privileged users and allowing them access to the system. For a while, I was well stymied in my attempts to access the MySQL using any of those extra accounts until I got the idea ofĀ associating them withĀ a host, another thing that is not needed in Ubuntu if my experience is any guide. All in all, Fedora may make you work a little extra to get things like thing done but I am not complaining if it makes you understand a little more about what is going on in the background, something that is never a disadvantage.
Over the course of it’s short history, this blog has had four different themes, the latest of which being my own customised variant of Dezzain’s Zoxengen. It’s predecessor’s have included Andreas04, Andreas09 and Prosumer. I have tinkered with all of these to varying degrees but each has offered me a certain something before I set about my tweaks. Zoxengen is no different and its clean lines and Web 2.0 feel attracted my attention. Other little features like seeing related posts listing on a post’s comments page or listing the tags associated with a post under its title line are, I hope, useful little extras. Correcting English (I may be digging a hole for myself here) and removing advertising slots (for me, this blogging business is a hobby so you’ll find no ads on any of my blogs) both seem to be a necessary tasks when implementing themes these times but the really major change was to make the design more flexible when it comes to different screen sizes, something that I hope to have achieved by allowing it to fill more of the browser window. There may be more changes, hopefully small, but I hope that you find the result as pleasing on the eye as I do.
Update: The blog’s current theme came with a lot of text that was written in poor English. While I should have got rid of all of it from the theme by now, there may be some still lurking here somewhere. If I find any more, it’ll get sorted. If something has escaped my notice for whatever reason, please let me know.
Though my main home PC runs Linux Mint, I do like to have the facility to use Windows software from time to time and virtualisation has allowed me to continue doing that. For a good while, it was a Windows 7 guest within a VirtualBox virtual machine and, before that, one running Windows XP fulfilled the same role. However, it did feel as if things were running slower in VirtualBox than once might have been the case and I jumped ship to VMware Player. It may be proprietary and closed source but it is free of charge and has been doing what was needed. A subsequent recent upgrade of video driver on the host operating system allowed the enabling of a better graphical environment in the Windows 7 guest.
Instability
However, there were issues with stability and I lost the ability to flit from the VM window to the Linux desktop at will with the system freezing on me and needing a reboot. Working in Windows 7 using full screen mode avoided this but it did feel as I was constrained to working in a Windows machine whenever I did so. The graphics performance was imperfect too with screening refreshing being very blocky with some momentary scrambling whenever I opened the Start menu. Others would not have been as patient with that as I was though there was the matter of an expensive Photoshop licence to be guarded too.
In hindsight, a bit of pruning could have helped. An example would have been driver housekeeping in the form of removing VirtualBox Guest Additions because they could have been conflicting with their VMware counterparts. For some reason, those thoughts entered my mind and I was pondering another more expensive option instead.
Considering NAS & Windows/Linux Networking
That would have taken the form of setting aside a PC for running Windows 7 and having a NAS for sharing files between it and my Linux system. In fact, I did get to exploring what a four bay QNAP TS-412 would offer me and realised that you cannot put normal desktop hard drives into devices like that. For a while, it looked as if it would be a matter of getting drives bundled with the device or acquiring enterprise grade disks so as to main the required continuity of operation. The final edition of PC Plus highlighted another one though: the Western Digital Red range. These are part way been desktop and enterprise classifications and have been developed in association with NAS makers too.
Looking at the NAS option certainly became an education but it has exited any sort of wish list that I have. After all, there is the cost of such a setup and it’s enough to get me asking if I really need such a thing. The purchase of a Netgear FS 605 ethernet switch would have helped incorporate it but there has been no trouble sorting alternative uses for it since it bumps up the number of networked devices that I can have, never a bad capability to have. As I was to find, there was a less expensive alternative that became sufficient for my needs.
In-situ Windows 8 Upgrade
Microsoft have been making available evaluation copies of Windows 8 Enterprise that last for 90 days before expiring. One is in my hands has been running faultlessly in a VMware virtual machine for the past few weeks. That made me wonder if upgrading from Windows 7 to Windows 8 help with my main Windows VM problems. Being a curious risk-taking type I decided to answer the question for myself using the Ā£24.99 Windows Pro upgrade offer that Microsoft have been running for those not needing a disk up front; they need to pay Ā£49.99 but you can get one afterwards for an extra Ā£12.99 and Ā£3.49 postage if you wish, a slightly cheaper option. There also was a time cost in that it occupied a lot of a weekend on me but it seems to have done what was needed so it was worth the outlay.
Given the element of risk, Photoshop was deactivated to be on the safe side. That wasn’t the only pre-upgrade action that was needed because the Windows 8 Pro 32-bit upgrade needs at least 16 GB before it will proceed. Of course, there was the matter of downloading the installer from the Microsoft website too. This took care of system evaluation and paying for the software as well as the actual upgrade itself.
The installation took a few hours with virtual machine reboots along the way. Naturally, the licence key was needed too as well as the selection of a few options though there weren’t many of these. Being able to carry over settings from the pre-exisiting Windows 7 instance certainly helped with this and with making the process smoother too. No software needed reinstatement and it doesn’t feel as if the system has forgotten very much at all, a successful outcome.
Post-upgrade Actions
Just because I had a working Windows 8 instance didn’t mean that there wasn’t more to be done. In fact, it was the post-upgrade sorting that took up more time than the actual installation. For one thing, my digital mapping software wouldn’t work without .Net Framework 3.5 and turning on the operating system feature form the Control Panel fell over at the point where it was being downloaded from the Microsoft Update website. Even removing Avira Internet Security after updating it to the latest version had no effect and it was a finding during the Windows 8 system evaluation process. The solution was to mount the Windows 8 Enterprise ISO installation image that I had and issue the following command from a command prompt running with administrative privileges (it’s all one line though that’s wrapped here):
dism.exe /online /enable-feature /featurename:NetFX3 /Source:d:\sources\sxs /LimitAccess
For sake of assurance regarding compatibility, Avira has been replaced with Trend Micro Titanium Internet Security. The Avira licence won’t go to waste since I have another another home in mind for it. Removing Avira without crashing Windows 8 proved impossible though and necessitating booting Windows 8 into Safe Mode. Because of much faster startup times, that cannot be achieved with a key press at the appropriate moment because the time window is too short now. One solution is to set the Safe Boot tickbox in the Boot tab of Msconfig (or System Configuration as it otherwise calls itself) before the machine is restarted. There may be others but this was the one that I used. With Avira removed, clearing the same setting and rebooting restored normal service.
Dealing with a Dual Personality
One observer has stated that Windows 8 gives you two operating systems for the price of one: the one in the Start screen and the one on the desktop. Having got to wanting to work with one at a time, I decided to make some adjustments. Adding Classic Shell got me back a Start menu and I left out the Windows Explorer (or File Explorer as it is known in Windows 8) and Internet Explorer components. Though Classic Shell will present a desktop like what we have been getting from Windows 7 by sweeping the Start screen out of the way for you, I found that this wasn’t quick enough for my liking so I added Skip Metro Suite to do this and it seemed to do that a little faster. The tool does more than sweeping the Start screen out of the way but I have switched off these functions. Classic Shell also has been configured so the Start screen can be accessed with a press of Windows key but you can have it as you wish. It has updated too so that boot into the desktop should be faster now. As for me, I’ll leave things as they are for now. Even the possibility of using Windows’ own functionality to go directly to the traditional desktop will be left untested while things are left to settle. Tinkering can need a break.
Outcome
After all that effort, I now have a seemingly more stable Windows virtual machine running Windows 8. Flitting between it and other Linux desktop applications has not caused a system freeze so far and that was the result that I wanted. There now is no need to consider having separate Windows and Linux PC’s with a NAS for sharing files between them so that option is well off my wish-list. There are better uses for my money.
Not everyone has had my experience though because I saw a report that one user failed to update a physical machine to Windows 8 and installed Ubuntu instead; they were a Linux user anyway even if they used Fedora more than Ubuntu. It is possible to roll back from Windows 8 to the previous version of Windows because there is a windows.old directory left primarily for that purpose. However, that may not help you if you have a partially operating system that doesn’t allow you to do just that. In time, I’ll remove it using the Disk Clean-up utility by asking it to remove previous Windows installations or running File Explorer with administrator privileges. Somehow, the former approach sounds the safer.
What About Installing Afresh?
While there was a time when I went solely for upgrades when moving from one version of Windows to the next, the annoyance of the process got to me. If I had known that installing the upgrade twice onto a computer with a clean disk would suffice, it would have saved me a lot. Staring from Windows 95 (from the days when you got a full installation disk with a PC and not the rescue media that we get now) and moving through a sequence of successors not only was time consuming but it also revealed the limitations of the first in the series when it came to supporting more recent hardware. It was enough to have me buying the full retailed editions of Windows XP and Windows 7 when they were released; the latter got downloaded directly from Microsoft. These were retail versions that you could move from one computer to another but Windows 8 will not be like that. In fact, you will need to get its System Builder edition from a reseller and that can only be used on one machine. It is the merging of the former retail and OEM product offerings.
What I have been reading is that the market for full retail versions of Windows was not a big one anyway. However, it was how I used to work as you have read above and it does give you a fresh system. Most probably get Windows with a new PC and don’t go building them from scratch like I have done for more than a decade. Maybe the System Builder version would apply to me anyway and it appears to be intended for virtual machine use as well as on physical ones. More care will be needed with those licences by the looks of things and I wonder what needs not to be changed so as not to invalidate a licence. After all, making a mistake might cost between Ā£75 and Ā£120 depending on the edition.
Final Thoughts
So far Windows 8 is treating me well and I have managed to bend to my will too, always a good thing to be able to say. In time, it might be that a System Builder copy could need buying yet but I’ll leave well alone for now. Though I needed new security software, the upgrade still saved me money over a hardware solution to my home computing needs and I have a backup disk on order from Microsoft too. That I have had to spend some time settling things was a means of learning new things for me but others may not be so patient and, with Windows 7 working well enough for most, you have to ask if it’s only curious folk like me who are taking the plunge. Still, the dramatic change has re-energised the PC world in an era when smartphones and tablets have made so much of the running recently. That too is no bad thing because an unchanging technology is one that dies and there are times when big changes are needed, as much as they upset some folk. For Microsoft, this looks like one of them and it’ll be interesting to see where things go from here for PC technology.
When I wrote about tidying dynamic URL’s a little while back, I had no inkling that that would be a second part to the tale. My discovery of mod_rewrite, an Apache module that facilitates URL translation. The effect is that one URL is presented to the user in the browser address bar, and the exact same URL is also seen by search engines, while another is passed to the server for processing. It might sound like subterfuge but it works very well once you manage to get it set up properly. The web host for my hillwalking blog/photo gallery has everything configured such it is ready to go but the same did not apply to the offline Apache 2.2.x server that I have going on my own Windows XP box. There were two parts to getting it working there:
Once you have got the above sorted, adding this line to .htaccess: RewriteEngine On. Preceding it with an Options directive to ensure that FollowSymLinks and SymLinksIfOwnerMatch are switched on does no harm at all and may even be needed to get things running. That done, you can set about putting mod_write to work with lines like this:
RewriteRule ^pages/(.*)/?$ pages.php?query=$1
The effect of this is to take http://www.website.com/pages/input and convert it into a form for action by the server; in this case, that is http://www.website.com/pages.php?query=input. Anything contained by a bracket is assigned to the value of a system-named variable. If you have several bracketed sections, they are assigned to sequentially numbered variables as follows: $1 for the first, $2 for the second and so on. It’s all good stuff when you get it going and not only does it make things look much neater but it also possesses an advantage when it comes to future-proofing too. Web addresses can be kept constant over time, even if things change behind the scenes. It means that returning visitors will find what they saw the last time that they visited and surely must ensure good karma in eyes of those all important search engines.
It has been a little while but I have managed to set up a VirtualBox virtual machine in order to take a look at the Developer Preview of the next version of Windows, something that I and others continue to call Windows 8 though Microsoft has yet to confirm the name. When I tried the installation before, it failed on me but that may have been due to having an earlier release of VirtualBox on my machine at that time. 4.1.14 has a preset for Windows 8 and I also happened to notice that it can create virtual hard disks that can be used with competitors like VMWare, Parallels and Virtual PC too. It’s an interesting development but I am left wondering why you’d need to do that when VirtualBox runs on most platforms anyway.
To get back to Windows 8, the installation ran near enough without any intervention apart form stating the language you wanted to use, U.K. English in my case. Starting up the operating system gains you a lock screen that you need to get out of the way so you can log in. It can be dragged out of your way or you can double-click on it or use the carriage return key to get rid of it. Quite why someone thinks it’s a good extra is a little beyond me when a log in screen would suffice. Logging in gets you the new start menu or, as I prefer to think of it, screen. By default, there are a good few Metro apps installed though I decided to rid myself of most of them.
Regarding those apps, one irritation could be that there isn’t that obvious a way to switch away from them to something else. Thankfully, ALT+TAB does seem to work and it has the most instantaneous effect. Otherwise, using the Windows key or hovering over the bottom left corner of the screen to get the menu that brings up the start screen. From the PC user’s point of view, I could see this needing a little more thought because it took a little while for me to figure out what to do. Closing Metro apps isn’t an option either unless you resort to the Task Manager to do so. Microsoft appears to want to leave them open from the point at which you start them until the PC is shut down. It’s a design decision that leaves me unconvinced though, particularly when thoughts of rogue apps running riot on a system come to mind. Then, a stop button could be handy.
There is no start menu as we have come to know it anymore with the start screen replacing it. However, it is possible to limit what’s on there to the software that you use most often an rearrange panels as you’d like them to be. Apart from hosting shortcuts for starting applications, it also acts as a task switcher like the task bar in Windows 7 and there is one of those in Windows 8 too when you jump to the desktop; handily, there’s a panel for that too. Installing Firefox added a panel to the start screen so a little thought has gone into such a common situation and that’s just as well. Still, there’s more work to be done because, currently, there’s no way of changing the background colour of the start screen without resorting to a hex editor or third party tools. Still, you can pick your own picture for the lock screen so things are not all locked down on you.
A preview of IE 10 is included and, apart from the occasional artifact when displaying one of my websites, it seems to work well enough as does Windows Explorer. However, apart from these and a smattering of Metro apps, the Developer Preview does feel barer that previous versions of Windows. However, it does appear that applications like Notepad, PowerShell and the Command Prompt are on there but you need to search for these. That also means that you know about them too so I’d suggest a better way of browsing the applications that are available too. This is one of the weaknesses of Ubuntu’s Unity interface and you need to search in the Dash to find them. Just starting to type in the Metro start screen (and other screens too, it seems) in Windows does trigger the completion of a search box much like what happens in the GNOME Shell Activities screen on systems with GNOME 3. While it’s good to see good ideas being reused from elsewhere, Microsoft might do well to note that you still can browse lists of applications in GNOME 3 too.
Shutting down Windows 8 also seems to be more convoluted than is the case with Windows 7. Logging off and then powering off from the log in screen is one approach and that was my early impression from GNOME 3 too. With the latter, I later was to discover a status menu plugin that added in the option where it was accessible or that using ALT key when clicking the status menu when the plugin wouldn’t work would do what I needed. Without logging off from Windows 8, you can do a shut down using the sidebar that appears on selecting Settings from the menu that pops up on hovering near the bottom left corner of the start screen or the Start button of the task bar of the desktop. Then, look for the power icon and select what you need from the menu that clicking on this icon produces. Of course, you may find that the ALT+F4 key combination when issued while on a clean desktop is the cleanest of all.
All in all, the Developer Preview of the next release of Windows looks fairly usable. That is not to say that there aren’t things that need changing. Apart from this being an early sight of what may be coming to us Windows users, it isn’t unknown for Microsoft to roll back on a radical move to make it more palatable to the user community. After all, it has to watch how it treats the corporate market too. The strong possibility of there being alterations is one thought that needs to be shared with those who are inclined to be losing their tempers at the moment and I have comments with unpleasant language out there on the web (none of that here, please, by the way). As for me, I like to look ahead in order to be forewarned about what’s coming my way in the world of computing. What I have seen so far of the next Windows release is reassuring though there are roughnesses such as PC shutdown and Metro app switching but Microsoft cannot commit commercial suicide either so these have to be fixed. It seems that the world of Microsoft operating systems is in flux with the company’s keeping a firm eye on the world of mobile computing with tablets being a major concern. Others may disagree but I can see Windows 8 working well on conventional PC’s and that’s no bad thing.
Turning dataset compression for SAS datasets can produce quite a reduction in size so it often is standard practice to do just this. It can be set globally with a single command and many working systems do this for you:
options compress=yes;
It also can be done on a dataset by dataset option by adding (compress=yes) beside the dataset name on the data line of a data step. The size reduction can be gained retrospectively too but only if you create additional copies of the datasets. The following code uses the DATASETS procedure to accomplish this end at the time of copy the datasets from one library to another:
proc datasets lib=adam nolist;
copy inlib=adam outlib=adamc noclone datecopy memtype=data;
run;
quit;
The NOCLONE option on the COPY statement allows the compression status to be changed while the DATECOPY one keeps the same date/time stamp on the new file at the operating system level. Lastly, the MEMTYPE=DATA setting ensures that only datasets are processed while the NOLIST option on the PROC DATASETS line suppresses listing of dataset information.
It may be possible to do something like this with PROC COPY too but I know from use that the option presented here works as expected. It also does not involve much coding effort, which helps a lot.
On checking the Site Health page of a WordPress blog, I saw errors that pointed to a problem with its SSL set up. The www subdomain was not included in the site’s certificate and was causing PHP errors as a result though they had no major effect on what visitors saw. Still, it was best to get rid of them so I needed to update the certificate as needed. Execution of a command like the following did the job:
sudo certbot --expand -d existing.com,www.example.com
Using a Let’s Encrypt certificate meant that I could use the certbot command since that already was installed on the server. The --expand and -d switches ensured that the listed domains were added to the certificate to sort out the observed problem. In the above, a dummy domain name is used but this was replaced by the real one to produce the desired effect and make things as they should have been.
With Linux/UNIX, the command line remains ever useful and allows you to do all manner of things, including file copying that only adds new files to a destination. Here’s a command that accomplishes this in Linux:
cp -urv [source] [destination]
The u switch does the update while r ensures recursion (by default, cp only copies files from a source directory and not anything sitting in subfolders)Ā and v tells the command to tell the user what is happening.
Though buried and hardly promoted, Windows also has its command line and here’s what accomplishes a similar result:
xcopy /d /u [source] [destination]
Anything’s better than having to approve or reject every instance where source and destination files are the same or, even worse, to overwrite a file when it is not wanted.