TOPIC: POWERSHELL
Saving Windows Command Prompt & Powershell command history to a file for later useage
15th May 2013It's remarkable 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 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 appears 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 is working on adding this useful functionality. While they could co-opt Cygwin of course, that doesn't seem to be their way of going about things.
Shell swapping in Windows: PowerShell and the legacy command prompt
28th April 2010Until 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.
Running Windows 7 within VirtualBox
12th January 2009With all the fanfare that surrounded the public beta release of Windows 7, I suppose that the opportunity to give it a whirl was too good to miss. Admittedly, Microsoft bodged the roll-out by underestimating the level of interest and corralling everyone into a 24-hour time slot, with one exacerbating the other. In the event, they did eventually get their act together and even removed the 2.5 million licence limit. Thus, I suppose that they really needed to get 7 right after the unloved offering that was Vista, so they probably worked out that the more testers that they get, the better. After, it might be observed that the cynical view that the era of making people pay to "test" your products might be behind us and that users just want things to work well if not entirely faultlessly these days.
After several abortive raids, I eventually managed to snag myself a licence and started downloading the behemoth using the supplied download manager. I foresaw it taking a long time and so stuck with the 32-bit variant so as not to leave open the possibility of that part of the process using up any more of my time. As it happened, the download did take quite a few hours to complete, but this part of the process was without any incident or fuss.
Once the DVD image was downloaded, it was onto the familiar process of building myself a VirtualBox VM as a sandbox to explore the forthcoming incarnation of Windows. After setting up the ISO file as a virtual DVD, installation itself was an uneventful process, yet subsequent activities weren't without their blemishes. The biggest hurdle to be overcome was to get the virtual network adapter set up and recognised by Windows 7. The trick is to update the driver using the VirtualBox virtual CD as the source because Windows 7 will not recognise it using its own driver repository. Installing the other VirtualBox tools is a matter of going to Compatibility page in the Properties for the relevant executable, the one with x86 in the file name in my case, and setting XP as the Windows version (though Vista apparently works just as well, I played safe and depended on my own experience). While I was at it, I allowed the file to run under the administrator account, too. Right-clicking on executable files will bring you to the compatibility troubleshooter that achieves much the same ends but by a different route. With the Tools installed, all was workable rather than completely satisfactory. Shared folders have not worked for, but that might need a new version of the VirtualBox software or getting to know any changes to networking that come with Windows 7. I plan to stick with using USB drives for file transfer for the moment. Though stretching the screen to fit the VirtualBox window was another thing that would not happen, that's a much more minor irritation.
With those matters out of the way, I added security software from the list offered by Windows with AVG, Norton and Kaspersky being the options on offer. I initially chose the last of these but changed my mind after seeing the screen becoming so corrupted as to make it unusable. That set me to rebuilding the VM and choosing Norton 360 after the second Windows installation had finished. That is working much better, and I plan to continue my tinkering beyond this. I have noticed the inclusion of PowerShell and an IDE for the same, so that could be something that beckons. All in all, there is a certain solidity about Windows 7, though I am not so convinced of the claim of speedy startups at this stage. Time will tell and, being a beta release, it's bound to be full of debugging code that will not make it into the final version that is unleashed on the wider public.
Automating FTP II: Windows
15th April 2008Having thought about automating command line FTP on UNIX/Linux, the same idea came to me for Windows too, and you can achieve much the same results, even if the way of getting there is slightly different. The first route to consider is running a script file with the ftp command at the command prompt (you may need %windir%system32ftp.exe to call the right FTP program in some cases):
ftp -s:script.txt
The contents of the script are something like the following:
open ftp.server.host
user
password
lcd destination_directory
cd source_directory
prompt
get filename
bye
It doesn't take much to turn your script into a batch file that takes the username as its first input and your password as its second for the sake of enhanced security and deletes any record thereof for the same reason:
echo open ftp.server.host > script.txt
echo %1 >> script.txt
echo %2 >> script.txt
echo cd htdocs >> script.txt
echo prompt >> script.txt
echo mget * >> script.txt
echo bye >> script.txt
%windir%system32ftp.exe -s:script.txt
del script.txt
The feel of the Windows command line (in Windows 2000, it feels very primitive, but Windows XP is better and there's PowerShell now too) can leave a lot to be desired by someone accustomed to its UNIX/Linux counterpart, yet there's still a lot of tweaking that you can do to the above, given a bit of knowledge of the Windows batch scripting language. Any escape from a total dependence on pointing and clicking can only be an advance.
Filename autocompletion on the command line
19th October 2007The Windows 2000 command line feels an austere primitive when compared with the wonders of the UNIX/Linux equivalent. Windows XP feels a little better, and PowerShell is another animal altogether. With the latter pair, you do get file or folder autocompletion upon hitting the TAB key. What I didn't realise until recently was that continued tabbed cycled through the possibilities; I was hitting it once and retyping when I got the wrong folder or file. I stand corrected. With the shell in Linux/UNIX, you can get a listing of possibilities when you hit TAB for the second time and the first time only gives you completion as far as it can go with certainty; you'll never get to the wrong place, though you may not get anywhere at all. This works for bash, but not ksh88 as far as I can see. It's interesting how you can take two different approaches to reach the same end.