Lee Holmes

Video: DIY Automatic Cat Feeder [2.3 mb]

I have two wonderful cats, and many wonderful neighbours.  Naturally, for my vacation, I combined the best of both worlds and had one of the neighbours watching my cats. Despite this, I didn’t want to force my neighbours to come over twice a day to feed the cats.  So I sought out to make an automated cat feeder and water dispenser out of parts lying around the house.

As for the …

[Edit 02/01/2012 - PowerShell added support for this in Version 2 via the following syntax:]

PS > $r = New-Object "System.Collections.Generic.List[Int]"
PS > $r.Add(10)
PS > $r.Add("Hello")
Cannot convert argument "item", with value: "Hello", for "Add" to type "System.Int32"
(...)
At line:1 char:1
+ $r.Add("Hello")
+ ~~~~~~~~~~~~~~~
+ CategoryInfo …

This has been coming up a bunch in the last little while, and I realized that I haven’t had a very good resource to point people to when they ask how to make a script or a function deal with pipeline input.

Scripts, functions, and script blocks all have access to the $input variable, which provides an enumerator over the elements in the incoming pipeline.  When pipelining is a core scenario, though,  these constructs …

After visiting 5 countries (Italy, Croatia, Greece, France, Spain,) 2 micro-states (Monaco, Vatican City,) and returning with a connection in Sweden, I’m back – and now 367% as worldly!

The vacation was truly eye-opening.  My only previous international experience (aside from growing up in Canada, and moving here to the United States) was a low-budget resort trip in the Dominican Republic.  That trip gave me a …

In my last post, I gave an example of how to use P/Invoke through PowerShell  to implement functionality not immediately available via the .Net framework.  My example was to get the owner of a process, and Abhishek wisely pointed out that  this is easier through WMI.

So here’s another example.  It’s actually the one I had written originally, but it didn’t give me an opportunity to illustrate [Ref] parameters, or [Out] …

An often asked question in the Managed Code world is “How do I get the owner of a process?”  The same question is starting to come up around PowerShell, and the answer to both is:

The .Net Framework does not yet support this API, so the solution is to write the P/Invoke calls into the Win32 API yourself.

This gets a little more complicated with PowerShell, though, since we abstract the .Net framework one level even …

One question that comes up frequently is, “Why does PowerShell not change its [System.Environment]::CurrentDirectory as I navigate around the shell?”

One of the difficult aspects of this comes from the fact that PowerShell supports multiple pipelines of execution.  Although it’s not directly exposed yet, users will soon be able to suspend jobs to the background, and other concurrent tasks.

The current directory affects …

One of Raymond Chen’s readers recently noticed that Google purchased AdWords for Raymond’s name.  The destination of the sponsored link?  http://www.google.com/jobs :)

This came up on our internal bloggers alias, so people started poking around to see what other bloggers / blog readership had outstanding “job offers.”  Not being one for repetitive, manual computer labour, I let PowerShell definitively answer the …

The question came up recently in an internal discussion list, “How do I search the Registry for a value in PowerShell?”

In the FileSystem, we have the select-string cmdlet to do the hard work for you.  We don’t have the equivalent yet for other stores, so unfortunately the answer is to write ‘grep’ from scratch.  It’s manageable, though.

The key here is to think of registry key values like you would think of content in …

The Where-Object cmdlet is incredibly powerful, in that it allows you to filter your output based on arbitrary criteria.  For extremely simple filters (such as filtering based only on a comparison to a single property,) though the syntax can get a little ungainly:

get-process | where { $_.Handles -gt 1000 }

For this type of situation, it is easy to write a function to offload all of the syntax  to the function itself: …