How to Grep in PowerShell:
Here’s some example commands in PowerShell to replicate Grep:
- Get-Process | Where-Object {$_ | Select-String “foo”}
- get-process | where ProcessName -like “*foo*
- get-process | findstr foo
- ps *foo*
Applies To : PowerShell
For those who have lived in the Linux/Unix command line, the ‘grep‘ command is a commonly used way of finding something that you want in a chunk of data.
Øyvind Kallstad did a great writeup of comparing a bunch of ways to use PowerShell instead of grep which is worth reading.
The article covers a bunch of scenarios, and is centered around starting with the ‘grep’ command and working with it. However, there’s the other common use case of running a different command, then piping those results to grep to search for something.
This blogpost was triggered by Janet who asked me this fair question:
As with poor cute cats, there’s more than one way to skin PowerShell.
I had to do some research and asking around on this, because normally I’d filter out the property of the object I was looking at, and work with that. Using the get-process example:
get-process | where ProcessName -like "*foo*
That works, but it’s still a lot clunkier than what a grep user would expect. An easier way would be to use the ‘findstr‘ program (which also has a bunch of useful swtiches):
get-process | findstr foo
I say program because ‘findstr’ is not a PowerShell cmdlet, but it’s still native to Windows and works perfectly fine. It’s case sensitive though, so you need to use -i for case insensitive results.
That’s great for simple stuff, but we’re sort of breaking what PowerShell does. You’re no longer dealing with a standard PowerShell object, so further piping and processing won’t really work.
The ‘proper’ PowerShell way would be to use the ‘Where-Object’ command:
Get-Process | Where-Object {$_ | Select-String "foo"}
A bit longer, but you can shorten ‘Where-Object’ to ‘Where’. Although more involved, it’s good to get into the habit of doing it this way, so when you’re piping this to the next command, it still says as a standard object that can be read and manipulated.’
(Update 24th Feb 2017) As Steve_N points out in the comments section, there’s a much shorter way of doing this:
ps *foo*
That’s it. Many PowerShell commands have inbuilt aliases, including ‘get-process’. You can see what this is with the command ‘get-alias -definition get-process’
This shows that ‘gps’ and ‘ps’ are both aliases to the command ‘get-process’. You can also create your own aliases with the ‘set-alias‘ command.
The ‘*foo*’ part works because the command assumes the -name switch has been used, which lets you define what criteria to search and show in the ProcessName field. This is the same way that many commands don’t need the -identity switch used, because it’s written to assume you’re going to tell it what identity/username/upn to work with.
This can also be piped to something else, so it’s a winner. It’s less ideal for scripts though, because it’s much harder to read, and you can’t assume that everyone will know the short alias of a full command.
Also note that this isn’t grep related at all, so part of the answer to the original question is that you may not even need grep or select-string as it adds unnecessary overhead of getting data and parsing it, whereas this updated example filters the data as it’s obtained.
(Update ends)
PowerShell isn’t a Linux/Unix command line, but Microsoft have incorporated many of the concepts from bash. If you still can’t bear to use PowerShell on Windows, there’s always the Linux Bash Shell on Windows.
Thanks again to Steve Mclnerey for the grep advice :)
Why Haven’t You Deployed LAPS Yet?
LAPS – Local Administrator Password Solution is an official Microsoft solution for doing exactly what it’s called – managing local administrator passwords on the computers you manage (both desktops and servers).
The solution is fairly simple – have a tiny client rolled out on each PC, that gets told by Group Policy to generate a random password. The local admin account gets set to that password, and Active Directory also gets told what that password is. That changes on a 30 day cycle
The end result is that anyone who obtains local admin access through that account, can’t access anything beyond that single computer – and, that’s only for 30 days maximum before it gets changed. Even if the computer is taken off the domain, your Active Directory will have a record against the computer of what the last set password was.
There’s a great overview, demo, and install files available from TechNet with Jessica Payne going into great detail on how it all works and showing you exactly what to do which I highly recommend after watching it personally.
As she says, it only takes 10 minutes or so to set up, and it’s that much more secure than using Group Policy to set everyone’s local administrator account to the same password (which by the way, doesn’t securely save the password in the Group Policy anyway) and running into issues when someone needs the local administrator password for one reason or another.
Oh, there is a tiny AD schema update, but it’s a single command and nothing to worry about :)
Once you’ve got LAPS set up, you use the LAPS UI program to view passwords:
Chris Brown has also written up a nice ‘how-to’ guide on setting up LAPS from end to end which is worth following too.
LAPS is easy to deploy, easy to manage and provides several security benefits… and it’s free. If you’re not using LAPS yet, it’s time to do it! Grab it from Microsoft here.
Gaming PC Build 2017
My 5+ year old PC was finally ageing – Battlefield 1 was maxing out the Intel i5 CPU! It’s time to upgrade to a whole new kit. After some research and help from PC Part Picker, this is what I bought:
Intel Core i7-7700K 4.2GHz Quad-Core Processor
Deepcool Gammaxx 400 CPU Cooler
MSI Z270 GAMING M5 ATX LGA1151 Motherboard
Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-3200C16 Memory
Intel 600p Series 512GB M.2-2280 Solid State Drive
Corsair 300R ATX Mid Tower Case Windows Edition
Corsair CS650M Modular 80 Plus Gold ATX Power Supply
You may notice there’s no GPU. I’ll be re-using my NVIDIA GTX970 as that was more recently updated. If I didn’t have that, I would have probably chosen a GTX1070. I also added in an old DVD drive and 1.5TB HDD because why not.
Notes from during the build:
Lining up the motherboard back panel into the case, and then getting the motherboard to line up with it. It looked like it was in place, but not enough to have the screws in the case line up with all the holes in the motherboard.
CPU Fan – Completely my fault, I put the wrong brackets on. I was still thinking of my old 1155 pin CPU when I followed the back of the box instructions, rather than the 1151 pins that my new CPU was. Then I had to work out how the weird clips worked, as there was a single line of instruction: “Well note: turn before push”. Apparently that means don’t turn at all, which took some trial and error to discover.
Working out how to install M.2 SSDs – this wasn’t really a problem, just something I hadn’t done before. It’s held in place with a screw and screw holder, which I eventually found already in the motherboard, but in a hole designed for the largest M.2 card possible.
This case is pretty good for HDDs and DVD Drives – it’s a screwless solution for both, but you do need to access both sides of the case. Both sides also come off easily with 2 thumb screws.
I did a bit of cable management, which previously I hadn’t bothered with as I’d be changing things around every couple of months (I remember adding my 9th 320GB HDD to my PC years ago, and then trying to juggle SATA and power cables around to make it all work). The case again was pretty good for this, I just fed the cables through to the bottom side of the motherboard, then brought them back out again where they needed to go.
CPU was just a drop in the right way, have the arrows line up job. Pushing the bracket back onto the CPU to hold it into place is a little worrying, more force is required then I was comfortable applying.
PSU is modular, so you can have just the cables you need coming out of it which reduces clutter. 650w is overkill I’m sure for this, as I could have bought a 550w for half the price but it wouldn’t have been modular, and I also like keeping my options open for future changes. Installation of the unit was sliding in and putting a couple of screws on.
The GPU I already had fits in with lots of room – it looks like they’ve changed the design of the PCI-E slot which used to have a plastic tab to bend to insert or remove the card – that’s changed to a tab that’s the same style as the RAM sockets.
RAM hasn’t changed at all installation wise :) The only trick is to make sure you populate the right slots – check the manual, but usually it’s also on the motherboard too (which it was in this case).
Idling temps after install were around the 39oC – but after overclocking and leaving it a few days, it seemed to settle lower at 37oC.
Getting the software going:
Thankfully after getting it all together and installing Windows 10, there were no issues. Lucky I installed that DVD drive, as the network device wasn’t installed with a default driver, and I had to load it off the included CD-ROM. Yep, 2017 and we’re still loading base drivers that way.
The amount of utilities provided by MSI is a bit silly, and it’s really hard to tell what any of them do until you install them. I’ve got one that claims to give a fast boot – the few seconds it takes without that is fast enough already. The MSI Command Center is useful as it shows CPU/RAM settings and speeds, as well as system temp. The MSI Gaming App was the one that let me turn off the motherboard’s LED, rather than setting it to ‘breathe’ where it would fade in and out in one of 7 amazing colours.
I also used the motherboard’s inbuilt overclocking ‘gaming mode’ option – it upped the CPU from 4.2Ghz to 4.8Ghz. I found another option around the RAM where I set that to 3200Mhz, and it did it’s thing on changing settings to match that RAM speed. If you’re not going to do this by the way, don’t get the ‘K’ series Intel I7, or RAM faster than 2400Mhz because that’s all it will run at out of the box.
Also, if you have a look at some comprehensive reviews you’ll see that there’s barely any benefit in the 7th generation Kaby Lake Intel CPUs vs the 6th generation Skylake (don’t ask me why Skylake is one word, and Kaby Lake is two words either), if you aren’t using the onboard GPU which gets the biggest gains. Right now, the price is pretty much identical between the 6700K and 7700K which is why you might as well go the newer one – there’s no negatives there.
This setup is very quiet too, there’s minimal noise from any fans which is great.
Here’s some pictures of the build process. I’m happy to report that after a few days and testing Battlefield 1, I’ve had zero blue screens, and CPU sits around 60% max when playing.
PowerShell – ‘While’ Loop Statement
There’s a lot of different ways to loop commands in PowerShell, and here’s one I just learnt (thanks Nathan Kewley for spending the time talking me through this!):
Scenario: You create a brand new user in Active Directory, but need to wait for things to sync before you make a change to the user. If you want to automate these steps, you want to check that the user exists before running more commands against it.
Answer: The ‘While‘ statement. This lets you loop a command ‘while’ something is a certain value. For example, you may want a script to loop for two minutes, or until a certain value is true or false.
With my script below, it will check if the value $running is nothing (null), which it is because we just made it up. Because it’s true, it’ll then continue on to do whatever is in the curly brackets. Here, I’m running a command the enable a user in Skype for Business, but also setting the result of that as the variable $running.
If the command works, $running now has a value of the created user, so as it loops again to see if $running is null, it won’t be, and the ‘while’ statement is done.
If the command fails however, and shows the dangerous red warning around the user not existing, nothing gets set to the $running variable. That means, when it loops again, $running will still be null so it’ll try again and again and again.
while($running -eq $null){
$running = Enable-CsUser -Identity testuser -SipAddress [email protected]
}
That’s rather dangerous of course, what if it’s forever $null? It’ll run forever, so we’d better put in some failsafes.
while($running -eq $null){
if($CheckUser -le '10'){
$CheckUser++
start-sleep -s 10
$running = Enable-CsUser -Identity testuser -SipAddress [email protected]
}
}
OK, this time we’re doing a couple more things. We’ve got two curly bracketed things to run now, the first is an ‘If’. If $CheckUser is less or equal to 10, then do the next curly bracket thing. The first time this runs that value again doesn’t exist because we just made it up, and nothing is less or equal to 10. The If statement is true, so it moves onto the next segment.
The $CheckUser++ command just adds ‘1’ to the value of $CheckUser – starting off at null or 0, so will turn into 1. As the statement loops, that number will increment all the way up to 11. Once it’s 11, the If statement is no longer true, so bombs out.
We’ve also added the start-sleep command, which is just a 10 second wait before doing anything. If we didn’t have that there, the 11 loops before it fails would be over incredibly quickly.
The last thing we can add is an event to occur once the ‘If’ statement is no longer true:
while($running -eq $null){
if($CheckUser -le '10'){
$CheckUser++
start-sleep -s 10
$running = Enable-CsUser -Identity testuser -SipAddress [email protected]
}else{
Throw "Unable to create SfB User"
}
}
All we’ve done here is added the ‘Else’ section, which only runs when the ‘If’ isn’t true. Once the $CheckUser variable hits 11, the ‘Else’ command runs and throws up an error, with the aptly named ‘Throw’ command.
Hopefully this is enough to explain the basics of the ‘While’ command.
Sponsored Message:
Tech Tip : Need to catch up with your pending programming work urgently? Get an instant access to all your programming tools by loading them into cloud with hosted virtual desktop from CloudDesktopOnline.com and access it remotely from preferred device(PC/android/iOS) at your convenience. If you prefer a server, Rent a server from www.Apps4Rent.com at an unbelievable cheap price.
Security Quality Rollup Confusion – Windows Updates
Since October 2016, Microsoft have updated their Windows Updates model (for Windows 7, 8.1, Server 2008 R2 SP1 and Server 2012 R2) to a more cumulative approach. To their credit, they had this communicated months before it started, and the word got around long before the first patch rolled out.
At the time I talked to Tom Walat who was reviewing what people thought of this model. There’s been a bit of confusion and changes in the model, including a new one for February 2017 where Internet Explorer will be seperated and have it’s own rollup. If you manage WSUS, you need to be across these changes.
There’s a great detailed blogpost on TechNet about the history and changes, as well as this really useful table:
Windows Updates for 7 and 8.1 table for Feb 2017 (source)
Here;s the TLDR version which is still long, sorry;
Since October 2016 to January 2017, there has been two main update rollups – a Security Monthly Quality Rollup which contains ‘all the patches’. In WSUS, this will have a name like “January, 2017 Security Monthly Quality Rollup for Windows 7”. There is a separate rollup for Windows 7, 8, Server 2008 R2 and 2012 R2. These are cumulative – each Rollup includes all previous rollup patches, but nothing that’s before October 2016. This is the recommended package.
There’s also the similarly named Security Only Quality Update which has just been ‘all the security patches’. This will have a very similar name, e.g. “January, 2017 Security Only Quality Update for Windows 7” again having a separate update for each OS. These are not cumulative, and each needs to be installed seperately. These updates are only required if you’re not doing the monthly rollup for some reason (e.g. one of the updates breaks something in the rollup).
Those both included Internet Explorer, but as of February 2017 that will be it’s own separate set of updates. The IE update set will be cumulative – including all older updates in each new package.
That separate IE set of patches is the Cumulative Security Update for Internet Explorer will be cumulative like the Rollups, where you only need the latest one.
These are big changes and it’s worth getting your head around it all – the end goal is to have only monthly updates for anything older than Windows 10.
There may be future changes as to how this model works, so make sure you keep up to date with what Microsoft is doing in this space.