Getting the folder name
Published April 30, 2013Consider the file information from get-childitem
PS> $file = ls servicesv0.6.txt
Fullname gives the full path to the file
PS> $file.Fullname
C:\MyData\SkyDrive\Data\scripts\servicesv0.6.txt
if you use DirectoryName you get the full path to the parent directory
PS> $file.DirectoryName
C:\MyData\SkyDrive\Data\scripts
The easiest way to get the folder holding the path is like this
PS> Split-Path -Path $file.DirectoryName -Leaf
scripts
However on a Windows 8/PS 3 setup you can also do this
PS> $file.Directory | select -ExpandProperty Name
scripts
Don’t go mad on a one liner
Published April 30, 2013Looking at my first group of entries for Beginners Event 1 I’ve noticed what seems like a fanatical attempt to squash everything onto one line.
command; command; command; command
is NOT a one liner. The ; marks the end of a line
command | command | command | command
IS a one liner, even if it goes onto multiple lines!
Don’t think one liner – think one PIPELINE
Read the Question
Published April 30, 2013When my children were at school and going off for a test or exam the last thing I told them was read the question.
It seems this needs to be repeated for the Scripting Games. The Beginners Event 1 involved MOVING files from one server to another. I have seen a significant number of answers that are COPYING files.
Close doesn’t count in the Scripting Games.
Please read the question before diving into an answer
WMI vs CIM speed tests–the final round
Published April 30, 2013As a final test I want to see what happened when I ran multiple commands against the remote machine.
PS> 1..100 |
foreach {
Measure-Command -Expression{1..100 | foreach {
Get-WmiObject -Class Win32_ComputerSystem -ComputerName W12SUS;
Get-WmiObject -Class Win32_OperatingSystem -ComputerName W12SUS;
Get-WmiObject -Class Win32_LogicalDisk -ComputerName W12SUS}}
} |
Measure-Object -Average TotalMilliseconds
Count : 100
Average : 6986.797156
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
PS> 1..100 |
foreach {
Measure-Command -Expression{1..100 | foreach {
Get-CimInstance -ClassName Win32_ComputerSystem -ComputerName W12SUS;
Get-CimInstance -ClassName Win32_OperatingSystem -ComputerName W12SUS;
Get-CimInstance -ClassName Win32_LogicalDisk -ComputerName W12SUS}}
} |
Measure-Object -Average TotalMilliseconds
Count : 100
Average : 8430.833188
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
PS> $sess = New-CimSession -ComputerName W12SUS
PS> 1..100 |
foreach {
Measure-Command -Expression{1..100 | foreach {
Get-CimInstance -ClassName Win32_ComputerSystem -CimSession $sess;
Get-CimInstance -ClassName Win32_OperatingSystem -CimSession $sess;
Get-CimInstance -ClassName Win32_LogicalDisk -CimSession $sess}}
} |
Measure-Object -Average TotalMilliseconds
Count : 100
Average : 3460.203938
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
WMI is slightly faster than CIM but using a CIM session is by far and away the fastest.
My conclusion is that WMI and CIM are comparable, with WMI having a slight edge for speed. If you want to run multiple commands against a remote machine you need to use a CIM session as it is way faster.
Backticks are baaaaaad; don’t do backticks
Published April 30, 2013The voting/judging process has started for event 1 in the 2013 Scripting Games. What I’m going to be doing over the next few weeks is point out some of the things that I’ve noticed when judging. Some will be good things that I think you should adopt; others will be bad things that you should avoid. There even may be some interesting stuff to get you thinking.
First off is the use of the backtick as a line continuation:
Get-Process | `
sort Handles –Descending
You don’t need a backtick at this point. The pipe symbol acts as a line continuation marker so the backtick is redundant. All you need to do is this:
Get-Process |
sort Handles -Descending
Its the same with commas. You don’t need to do this:
Get-Process |
select Name, Id, `
Handles, CPU
because it works without the backtick
Get-Process |
select Name, Id,
Handles, CPU
You may see backticks used a lot in books but that is an attempt to reduce the width of the code to make it fit the page. We want you to be able to copy the code from the ebook and run it. The alternative is a line continuation marker which you would have to remove.
Bottom line – 99.9% recurring of the time you don’t need backticks as line continuation markers
CIM vs WMI cmdlets-remote execution speed
Published April 29, 2013Following on from my previous post we’ll look at how the two types of cmdlets compare for accessing remote machines.
I used a similar format to the previous tests but was accessing a remote machine.
First off was the WMI cmdlet – using DCOM to access the remote Windows 2012 server
PS> 1..100 |
foreach {
Measure-Command -Expression{1..100 | foreach {Get-WmiObject -Class Win32_ComputerSystem -ComputerName W12SUS }}
} |
Measure-Object -Average TotalMilliseconds
Count : 100
Average : 2084.122547
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
The CIM cmdlets are similar but apparently a bit slower – probably due to having to build the WSMAN connection and teat it down each time.
PS> 1..100 |
foreach {
Measure-Command -Expression{1..100 | foreach {Get-CimInstance -ClassName Win32_ComputerSystem -ComputerName W12SUS }}
} |
Measure-Object -Average TotalMilliseconds
Count : 100
Average : 2627.287458
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
So what happens is you run the CIM command over a CIM session?
PS> $sess = New-CimSession -ComputerName W12SUS
PS> 1..100 |
foreach {
Measure-Command -Expression{1..100 | foreach {Get-CimInstance -ClassName Win32_ComputerSystem -CimSession $sess }}
} |
Measure-Object -Average TotalMilliseconds
Count : 100
Average : 877.746649999999
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
This removes the setup and tear-down of the WSMAN connection. It suggests that the actual retrieval time for the CIM cmdlets should be reduced to 1749.540808 milliseconds for 100 accesses which is faster than the WMI cmdlets
It looks like the fastest way to access WMI information is across a CIM session. Next time we’ll look at running multiple commands
AD Management in a Month of Lunches– chapter 9 in MEAP
Published April 29, 2013The MEAP for AD Management in a Month of Lunches has been updated with the release of chapter 9 on managing group policies
CIM cmdlets vs WMI cmdlets–speed of execution
Published April 28, 2013One question that came up at the summit was the comparative speed of execution of the new CIM cmdlets vs the old WMI cmdlets. No of us knew the answer because we’d never tried measuring the speed.
I decided to perform some tests.
This first test is accessing the local machine. In both cases the cmdlets are using COM. WMI uses COM and CIM will use COM if a –ComputerName parameter isn’t used.
The results are as follows:
PS> 1..100 |
foreach {Measure-Command -Expression {
1..100 | foreach {Get-WmiObject -Class Win32_ComputerSystem} }
} | Measure-Object -Average TotalMilliseconds
Count : 100
Average : 2008.953978
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
PS> 1..100 |
foreach {Measure-Command -Expression {
1..100 | foreach {Get-CimInstance -ClassName Win32_ComputerSystem} }
} | Measure-Object -Average TotalMilliseconds
Count : 100
Average : 2078.763174
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
So for pure COM access the WMI cmdlets are marginally (3.4%) faster.
What if we use the ComputerName parameter?
PS> 1..100 |
foreach {
Measure-Command -Expression {
1..100 | foreach {Get-WmiObject -Class Win32_ComputerSystem -ComputerName $env:COMPUTERNAME } }
} | Measure-Object -Average TotalMilliseconds
Count : 100
Average : 1499.14379
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
PS> 1..100 |
foreach {
Measure-Command -Expression {
1..100 | foreach {Get-CimInstance -ClassName Win32_ComputerSystem -ComputerName $env:COMPUTERNAME } }
} | Measure-Object -Average TotalMilliseconds
Count : 100
Average : 3892.921851
Sum :
Maximum :
Minimum :
Property : TotalMilliseconds
This one surprised me – the WMI cmdlets are 2.5 times faster. I suspect that is because the CIM cmdlet has to build and then breakdown the WSMAN connection each time.
Next time we’ll look at accessing a remote machine.
Time for D-CRUD?
Published April 28, 2013I was thinking on the plane back from the PowerShell summit about the CRUD activities. They are a concept we have inherited from the database world:
C = Create
R = Read
U = Update
D= Delete
Create, Update and Delete correspond directly to the PowerShell verbs – New,Set and Remove respectively.
The Read action corresponds to the Get verb.
Well sort of.
Get-* is used in two distinct scenarios. Firstly we know of an object and we we want to read its properties – for example:
Get-Process -Name powershell
We are reading the information about the PowerShell process. That corresponds directly to the Read action in the CRUD paradigm.
However, we also use Get* when we want to Discover the processes that are running:
Get-Process
In which case we are Discovering the processes that are running.
I think its time to update the CRUD concept and make it DCRUD where D stands for discovery.
Scripting Games 2013 have started
Published April 28, 2013The 2013 Scripting Games kicked off during the PowerShell summit. Event 1 is open and you can submit entries up until 23:59:59 GMT on 29 April 2013. Voting on the entries starts at at midnight on 30 April.
You can enter and you can vote on the entries. This is a community games run by powershell.org – all are welcome.
If you haven’t entered yet there is still plenty of time to get you entry in for event 1. Start by reviewing the information at http://powershell.org/wp/the-scripting-games/
Enjoy and good luck