It was so weird driving to work and hearing a segment about Xandros and Firefox on Radio National (MP3 recording). For a few minutes, I thought I had passed into some bizarro open-source world because the presenters hardly mentioned Microsoft Windows.
2008-06-21: Updated MP3 link.
I never expected to find this bug. In Windows XP, if you try to copy and paste a task in the Scheduled Task folder, you may get this error message: Cannot copy <Task Name>: The source and destination file names are the same.
Even the obvious workaround doesn't work: copy a task, rename the original and paste the new task. unlike Windows Explorer, Scheduled Task doesn't seem to give a copied task a name such as Copy of x.
Microsoft's PowerShell is a scripting environment based on the .Net framework. PowerShell is aimed at replacing Windows Cmd and Windows Scripting Host (WSH) for administrative tasks. What interests me is that I can use .Net objects interactively and in a script, without having to write and compile a program. As I explore PowerShell, I'll write about features that I find interesting and useful.
In this first article, I describe really basic use of the PowerShell console. I assume you downloaded and installed Powershell.
Powershell installation provides a lot of on-line help. You obtain information using the get-help cmdlet (essentially a built-in command). There's so much information that the trick is to figure out the appropriate help topic:
> help # or 'get-help'
< 299 lines … >
> help about_Arithmetic_Operators
TOPIC
Arithmetic operators
SHORT DESCRIPTION
Operators that can be used in the Windows PowerShell to perform
mathematical operations
…
You can also download the on-line help as a CHM file (search for "Windows PowerShell Graphical Help File").
You can enter commands for processing immediately:
> 'abc' + 'def' # String concatenation abcdef > 5+6 # Addition 11 > 5*6 # Multiplication 30 > 30%7 # Remainder 2
The '#' marks the start of a comment. All text from '#' to the end of the line is a comment.
How long is a string (said with a straight face)? Since we are using .Net String objects, each string should have a Length property:
> 'abc'.Length
3
> 'def'.Length
3
> ('abc' + 'def').Length
6
You can find the methods of an object using get-member.
> 'abc' | get-member TypeName: System.String Name MemberType Definition ---- ---------- ---------- … get_Length Method System.Int32 get_Length() …
What's 2 to the power of 8? The .Net System.Math class defines a set of common mathematical functions. Again, you can use the get-member cmdlet to find out what functions are available in any class, but this time, with the -static option because the class, not individual objects, define these functions.
> [math] | get-member -static TypeName: System.Math Name MemberType Definition ---- ---------- ---------- … Pow Method static System.Double Pow(Double x, Double y) … > [math]::Pow(2,8) 256
The System.Math is pre-loaded by PowerShell and can be accessed as [System.Math], [Math] or [math]. Square brackets refer to .Net classes and some aliases have been defined for these classes.
How do you know whether an object or a class has the required function? No easy answer: trial-and-error, and experience with other class libraries.
It's pretty tedious typing a full cmdlet string, so there are two shortcuts available: tab expansion and aliases.
If you enter get-m<TAB>, you should see Get-Member. For some reason, you have to enter the name of cmdlet up to the '-' (dash) character before tab expansion works.
The get-member cmdlet also aliased as gm. What aliases are available? Use the get-alias cmdlet, which is also aliased as gal, for a list of available aliases.
> Get-Alias CommandType Name Definition ----------- ---- ---------- Alias gal Get-Alias … Alias gm Get-Member …
At this point, you can run some simple commands using PowerShell and know how to find some on-line information.
During the development and test phase of a project, I have to install and uninstall daily program builds for testing, so I'm pretty interested in reducing the amount of time and effort required to uninstall programs. Here's how my uninstallation process evolved:
In the beginning, use Start / Control Panel / Add or Remove Programs.
Spend less time by starting Windows' Add or Remove Programs dialog using the Run dialog by typing Windows+R appwiz.cpl.
Then you might notice that the Windows XP Add or Remove Programs dialog takes up to 30 seconds to start and there's no quick way to find the desired program. It's annoying that the list of programs doesn't scroll when you hit the PageDown and PageUp keys or when you type the first few letters of a program name. (The Vista equivalent, Programs and Features, doesn't have these limitations.)
Finally, using Windows Installer, msiexec, you could uninstall any program if you have the ProductCode. Just create a desktop shortcut with the following string in the Target field:
C:\WINDOWS\system32\msiexec.exe /uninstall <ProductCode>
P.S. You can find the ProductCode of your program using this script.