A question recently came up asking why the -eq operator doesn’t work for two different (but equal) SecureStrings.

By default, almost all environments (the .NET Framework included) test if two things are exactly the same – that they are stored in the same place in memory. This is called reference equality.

[D:\documents\WindowsPowerShell]
PS:14 > $test = Read-Host -AsSecureString
****

[D:\documents\WindowsPowerShell]
PS:15 > [Object]::ReferenceEquals($test, $test)
True

[D:\documents\WindowsPowerShell]
PS:16 > $test -eq $test
True

That’s not usually what people want, so each individual type of object is (optionally) responsible for supporting a value-based equality test. They do this by implementing interfaces (software contracts) called IComparable and / or IEquatable:

I’m not particularly a drum fan, but this is an amazing feat of skill and technology.

Since I injured my middle left finger playing Guitar Hero 2 way too much when it came out, I’ve been dying to get back to playing it. … so I thought “wouldn’t it be great to be able to play Guitar Hero on the drums?” So I thought about how that might be accomplished… researched, implemented, borrowed, and here I outline the finished product.

The ACoupleOfAdmins blog recently posted a book review of the PowerShell Cookbook (and were kind enough to also write an Amazon Review.) They bring up some excellent points. Mainly,

The Windows PowerShell Cookbook will stay on my shelf as a reference book (for the code samples), but I would look to other resources first (e.g. Windows PowerShell In Action by Bruce Payette), if you need a resource to help learn PowerShell.

I thought long and hard about the depth and breadth of the book. One theme they’re picking up on is that the PowerShell Cookbook is not a language focused book, and does not go into gritty detail about each language feature. This is intentional, as I wanted the book to have a very clear and unique value. We already have one PowerShell in Action, so there’s really not a need for another.

A question came up on the newsgroup recently about why Exchange changes PowerShell’s execution policy from “Restricted” to “RemoteSigned.” Doesn’t that lower PowerShell’s security?

The “Restricted” execution policy isn’t intended to be something that PowerShell users live with forever. It’s a safe default that protects non PowerShell users from being impacted by PowerShell-based malware.

For example, many home users had never used VBScript, but still got bitten by the flurry of WSH-based viruses that got mailed to them. PowerShell’s Restricted execution policy solves this. To an attacker, a computer that has never used PowerShell is the same as a computer that doesn’t have PowerShell installed at all. And since attackers care look to affect the largest number of computers possible, PowerShell becomes a less attractive vehicle for their attack. That, in turn, makes PowerShell users safer too. Given all of PowerShell’s security barbs, an attacker is better off using executables or other popular scripting languages as an attack vehicle.

Here’s a nice light-hearted video if you need a laugh :)

Video: William laughing

Since we just released a CTP of PowerShell V2, I thought I’d share a handy little script to demonstrate one of the new APIs we introduced: Show-ColorizedContent.ps1.

This CTP introduces a new tokenizer API that lets you work with PowerShell script content the same way that our parser does – as a collection of items (tokens) that represent the underlying structure of that script Until now, any tool that works with the data of a PowerShell script needs to parse the script on its own – usually with fragile regular expressions or other means.

Scott Hanselman and I recently chatted about using PowerShell for a bit of log analysis. The majority of his solution (in green) ended up being quite elegant, flowing into a pipeline nearly as easily as you might speak it:

PS C:\> $re =[regex]"\d{2}(?=[_.])"; import-csv file.csv |
    select File, Hits, @{Name="Show";Expression={$re.matches($_.File)[0] } } |
    sort Show -desc | group Show |
    select Name,{($_.Group | Measure-Object -Sum Hits).Sum }

(Of course, one should never pronounce a regex aloud in polite company.)

Update 8/16/2010: The much expanded second edition is now available.

As just announced by O’Reilly, the PowerShell Cookbook is now available!

As your experience grows in any technology, you learn and benefit from the combination of two distinct types of knowledge:

1. What can I do with the technology?
2. How do I accomplish a specific task in that technology?

Question #1 focuses on the technology. You learn the answers to #1 from training, exploration, podcasts, and technology-specific books. This is where you immerse yourself in the looping constructs, variable syntax, etc. In PowerShell’s case, that’s (not surprisingly) turned out to be PowerShell in Action, along with the many other excellent PowerShell learning resources out there.

When you’ve got to deal with as much information as everybody in a large company does, most people write Inbox rules to redirect DLs to their own sub-folders. They then group the folder “By Conversation,” which lets them quickly read the threads of interest. But most importantly, it lets them ignore the ones that do not.

If you don’t yet use these techniques to help you manage your own mail, you will love yourself for starting. I may follow up with a post in the future about that, but it’s a staple in email management in any large company.

A few weeks ago, Design News ran an engineering-centric article on the DIY Cat Feeder that entertained my cats while I was on vacation last year. Everybody loves a good hack, but I’ve been surprised by the attention it received. If you’ve been wanting to know more about how it was built, the article provides much more detail.

As part of their article preparation, they asked for mechanical and schematic drawings, along with part numbers from anything in the Allied Electronics catalog that the cat feeder used. Since my main goal was to make something out of random junk laying around the house, I thought the question was a little funny – as the parts list ended up being: