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Filter vs Include

I’ve gone through most of the Beginner event submissions over the last couple of days. One thing that has jumped out is the potential misunderstanding around using the –include or –filter parameters on get-childitem. If we look at the...

Published Wed, May 05 2013 3:19 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics, Powershell, Scripting Games

Piping between functions

A question came up about piping between advanced functions. The input to the second function might be an array. To illustrate how this works imagine a function that gets disk information – or better still use this one. function get-mydisk { [ CmdletBinding...

Published Sat, Jan 01 2013 2:13 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Passing function names

A question asked about passing a function name into another function which then called the function. It sounds worse than it is. if you need to pass the name of a command and then call it try using invoke-expression function ffour { Get-Random } function...

Published Wed, Jan 01 2013 4:33 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Select-string – keeping in context

Today’s question involves using the Context parameter: It's probably just me, but I've never gotten the switch '-context 5 or -context 2, 7' to work predictably - where 5 lines before and after or 2 before and 7 after will come...

Published Fri, Jan 01 2013 1:41 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Select-String - finding the first and last matches

Today's question concerns finding the first and last matches in a file Sometimes, I need to make two passes at seeking content in this file, once for the first occurrence; and a second grep for obtaining the last occurrence of a phrase. After the...

Published Wed, Jan 01 2013 11:56 AM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Select-String–information on matching files

Following on from yesterday’s post this is the second question: Since I'm recursively searching thru files to find matching phrases, how can I obtain other directory service information about the matching files file(s) - this is more of a methodology...

Published Tue, Jan 01 2013 3:32 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Select-String scenarios – fixed columns

I had some questions come in after mu recent post regarding select-string. I’ll answer them as a series of posts. First off: I'm recursively searching thru many files, and want to pull out specific data in 'fixed column' positions from...

Published Mon, Jan 01 2013 4:43 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Select-String confusion

I have seen a lot of confusion recently over the use of Select-String. One mis-conception is that you need to use Get-Content to pipe the file contents into Select-String. Not so. Select-String will read the file for you. If you just want to scan...

Published Sat, Jan 01 2013 7:10 AM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Ensuring that parameter values are passed to your function

A question on the forum about a function had me thinking. The user had defined two parameters for the function and then used Read-Host to get the values. NO Much better way is to use an advanced function and make the parameters mandatory function Getuserdetails...

Published Thu, Jan 01 2013 12:48 PM by Richard Siddaway's Blog

Filed under: PowerShell V2, PowerShell Basics, PowerShell and Active Directory, PowerShell V3

A switch in time

I’ve posted about the switch statement a number of times but it is one of those topics that keeps coming up. Imagine you have a variable that can take one of several values. Depending on the value you might want to perform different actions like this...

Published Fri, Nov 11 2012 2:40 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Random confusion

There seems to be a bit of cofusion about how Get-Random works. Try this 1..10 | foreach {Get-Random} you’ll get randomly selected 32-bit unsigned integer between 0 (zero) and Int32.MaxValue (0x7FFFFFFF, 2,147,483,647). The –Minimum parameter sets...

Published Sun, Sep 09 2012 8:08 AM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Write-Host Wrong!

Many scripting languages require you explicitly write out to screen – VBScript was an example. This leads to PowerShell that looks like this Get-Service | foreach { Write-Host $_.Name, $_.Status } This is bad on so many levels. Firstly you are...

Published Tue, Jun 06 2012 2:52 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

How do I do X in PowerShell?

Many forum questions revolve around that question. In some cases the answer is that its not possible. It might not be possible because PowerShell itself can’t do something BUT it is much more likely that there just isn’t away to do that particular...

Published Mon, Jun 06 2012 1:04 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Pipeline input

A question on the forum asked about creating a function that accepts pipeline input OR has a path parameter. Means it can be used like this myfunction -Path C:\scripts\Test\proc.csv or (Get-Content C:\scripts\Test\files.txt) | myfunction First create...

Published Wed, Jun 06 2012 4:35 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

Some thoughts on hash tables

I need to test the existence of an element in a hash table. First create a hash table $myht = DATA { ConvertFrom-StringData -StringData @' 1 = aaaaaaa 2 = bbbbbbb 3 = ccccccc 4 = ddddddd 5 = eeeeeee '@ } I tend to create them using ConvertFrom...

Published Mon, May 05 2012 2:26 PM by Richard Siddaway's Blog

Filed under: PowerShell Basics

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Filter vs Include

Piping between functions

Passing function names

Select-string – keeping in context

Select-String - finding the first and last matches

Select-String–information on matching files

Select-String scenarios – fixed columns

Select-String confusion

Ensuring that parameter values are passed to your function

A switch in time

Random confusion

Write-Host Wrong!

How do I do X in PowerShell?

Pipeline input

Some thoughts on hash tables