Archive for
January 2007
Last weekend, I asked my wife if she could think of anything inappropriate or unusual to do with PowerShell. She came up with some good ideas and one of them was to write a chat/IM client.
A full client takes time, so with a nod toward PowerShell’s administrative uses, I wrote a script that forms the basis of an IRC chat bot.
This script can be used to pipe messages to a chat channel and/or join a set of channels, returning all messages posted there.
I’ve sure most of you out there use Microsoft MSN Windows Live Messenger, or even Yahoo! or AOL, so this may just serve as an example of synchronous TCP/IP messaging in PowerShell.
You can download the script here: chat-irc.ps1.
You may need to unblock it according the the instructions in help about_signing.
Read on »
Over the weekend, I set about writing an IRC chat client/channel monitoring tool in PowerShell (more on that in a day or so) and one of the things I was doing a lot was writing verbose and debug information to the console.
By default, Write-Verbose and Write-Debug cmdlets write nothing to the console, because the the value of the variables $VerbosePreference and $DebugPreference respectively are “SilentlyContinue”.
If you set them both to “Continue” the text is written to the console, but both in bright yellow on black (I wonder why?), like this:
PS> $DebugPreference="continue"
PS> $VerbosePreference="continue"
PS> write-debug "debug msg"
DEBUG: debug msg
PS> write-verbose "verbose msg"
VERBOSE: verbose msg
These colours can be changed so you can more easily distinguish between debug and verbose messages, and also not have the real output swamped.
Read on »
Over at the excellent PowerShell Team Blog, Bruce Payette wrote about Controlling PowerShell Function (Re)Definition.
However, making a function constant does not prevent it from being shadowed in child scopes. Given that a child scope is created in any script, new function definition or script block, this makes it very unconstant.
Read on »
A while back, I posted an article: Console screen grabs in html.
I fixed some bugs and added a couple of new features to the script get-bufferhtml.ps1, and have updated the article with examples.
Enjoy!
Ever wanted to control a PowerShell session from a web browser or curl/wget on another machine?
Yes? Well it surprisingly simple using PowerShell to script the System.Net.HttpListener. Here’s a working example with some genuine uses (well useful for me).
I’ll leave all the security and risk concerns as an exercise for the reader 
Read on »
In the unix world, we’re used to being able to run the different commands in a pipeline in different threads/processes. This is usually a lot more efficient when the producer/consumer rates vary, and makes use of multiple cores/cpus.
For example, cmd1 | cmd2 will run the two commands in separate processes.
PowerShell doesn’t do this. Everything runs in one thread, and pipelined objects are processed in batches, one bit at a time. You can control the batch size with the -outBuffer parameter, but things are still done sequentially, with one command in the pipe being busy whilst all others are sitting idle.
Even the venerable CMD.exe will put these two commands tree | more into separate processes.
This aside, what about simply running an arbitrary command (or scriptblock) in the background whilst doing something else?
Read on »
In the old days, when you printed something out, you’d have to wander down to the print room and find your output in a stack of fanfold with the job name printed as a large banner on the top. I miss those days so I wrote a banner script to do this:
Read on »
NTFS has the ability to associate multiple data streams (aka forks) to a file. It’s not very well supported in most Microsoft tools and not very well known, but I use them quite a bit for associating metadata with files.
Unfortunately, PowerShell (or rather .NET) doesn’t support them very well.
Read on »
Many built-in cmdlets take input from the pipe, but alternatively let you specify an input with the -InputObject parameter. An example is the Get-Member cmdlet.
I want to be able to do this with my own functions, but as far as I can tell, there is no built-in mechanism for this for using an specified parameter instead of the pipe.
[Updated]
Read on »
I really like the way that PowerShell handily formats pipeline objects when displaying them in the console, eg get-childitem in a file system directory returns a collection of file objects and the output is like the old DOS dir command.
Additionally, I really like the way that hashes behave like objects with named properties. For example:
$a=@{"name"="bob";"age"=42}
$a.name # outputs "bob"
$a.age # outputs 42
Unfortunately, if you have a list/array of hashes with the same keys, you cannot benefit from this built-in formatting. The output comes out in two columns, keyed Name and Value.
I want a way to have the properties of the hash be the keys and the values be the values associated with those keys.
Read on »
