Thursday, December 29, 2005

5 Minutes with Monad

I've recently spent a bit of time trying to solve some problems using Microsoft's new Monad shell. It's interesting that the creature for the O'Reilly book is the common toad. It was a different experience, although the pain is eased a little as the default installation comes with all the new commands (cmdlets) mapped to Unix ones (like ls and ps).

The default security setting prevents remotely signed objects from being executed and there seems to be no way to turn it on. The documentation is missing. To make it usable it's:
-property ExecutionPolicy -value RemoteSigned

Going through the tutorials it did show itself to be kind of cool. For example, being able to select the top 10 processes based on VirtualMemorySize:
get-process | sort-object VirtualMemorySize | select-object -last 10
You can whack on a "convert-HTML" or an "export-csv" to produce the result in a format you want or connect to Excel or SQL Server to retrieve data. A lot has been made of its native XML support and how it passes around strongly typed objects rather than just Unix's streams.

One of the problems was trying to do line by line processing. There was promises of pipelining via XML streams but according to "Replace lines in a text file?" (the first hit on Google) Monad doesn't support it. The lack of streaming appears to be a crucial omission in a toolset designed for system administrators - although it might not be fatal as log files and the like don't usually come close to the available memory of modern systems.

It does support accessing the .NET APIs which provides a loophole. For example, to read a file line by line and replace "xxx" with "yyy":
$f = [System.IO.File]::OpenText("c:\file.txt")
while($line = $f.ReadLine())
$line -replace "xxx","yyy"

It was all for nothing, as I later found out that it didn't support Windows 2000 and it needed to be deployed on that - it is supported by Windows XP, 2003 and Vista. Back to Windows Script Host (maybe using Ruby) I guess.
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