How to search output with PowerShell

rc4

We had a sysadmin (with whom I was never particularly impressed) write a script that deletes cached windows credentials for certain websites using powershell.

Here's what his code looks like:

$a = cmdkey /list:cached.site.com
     if ($a -match "cached.site.com") { cmdkey /delete:cached.site.com }
     else { Exit-PSSession }

I was impressed that his script had worked on the first try. But when I went to update it, I noticed it always tried to delete the credentials, regardless of whether they were cached or not. This wasn't a big issue; the script still worked. But it defeated the whole purpose of the if statement. Why did this happen? Let's take a look at the output of cmdkey /list:google.com:

Currently stored credentials for google.com:

* NONE *

flabdablet

cmd script to implement the same logic, except correctly:

for /f "tokens=1*" %%A in ('cmdkey /list:cached.site.com') do (
    if "%%A" == "Target:" cmdkey /delete:"%%B"
)

But how lucky we are to have this shiny new object oriented shell that has finally managed to make the ad-hoc parsing of command text output a thing of the past.

ben_lubar

Can't they just set an exit status like a normal CLI?

flabdablet

Very few Microsoft CLI tools are actually designed to interwork sanely with anything else; cmdkey certainly isn't. I've done quite a lot of scripting on MS platforms, one way or another, and in my experience relying on the exit status for console commands works for about one in four.

rc4

Yeah, most everything I do as far as scripting things via the Windows CLI involves parsing the output of commands in various ways. Powershell alleviates some of these headaches, however.

LB_

This reminds me of when I spent hours Googling how to extract a path from the registry in Windows Batch Script file without weird external dependencies. I ended up with this and a headache. I've decided to not mess with Batch since.

rc4

Yeah, I've done some TR stuff in batch as well. Powershell handles everything a lot better, so I decided to learn it. No regrets.

YellowOnline

Replace your code with this:

[code]
$a = @(cmdkey /list:cached.site.com)
If ($a[3] -NotMatch '* None *'){cmdkey /delete:cached.site.com}
[/code]

Powershell is great by the way. I won't shed a tear for batch or VBS.

rc4

@YellowOnline said:

Powershell is great by the way

Agreed. I just replaced it with the three cmdkey /delete commands as running them without any credentials doesn't hurt anyone.

tar

I've used System.Xml.Linq (or was it System.Linq.Xml?) from PowerShell to run arbitrary one-off transformations on a whole shitload of .vxcproj files that I couldn't be bothered to edit by hand...