Quick Tips: Counting in PowerShell

 PowerShell, Quick Tips  No Responses »
Jan 302013
 

If you’re like me, sometimes you just feel like counting. Well, in PowerShell you can count easier than ever before! PowerShell gives you ability to not only easily increment, but also run code for each increment because you can pipe! First, let’s take a look at the basic code:

And why limit yourself to counting up?! You can even decrement those numbers:

So, how can you use this? Well, remember the wonderful thing called a pipeline. You can potentially ping an entire subnet with the following command:

Remember, if that command takes too long, you could consider multithreading it with one of the scripts on this site!

Quick Tip: Newlines when Typecasting Arrays to Strings

 PowerShell, Quick Tips  3 Responses »
Aug 302012
 

Converting arrays into strings can cause a couple different problems, and I am starting to see more and more people struggling. The problem is that it doesn’t always act like you think it should. By default, converting an array into a string will place every item on one line of text separated by a space. This is particularly true with arrays made by get-content that are typecast into a string.

The answer is very simple. When you type cast an array into a string every field is separated by a secret value (not so secret anymore!) called the Object Field Separator, or OFS. This value is keep in a variable called $OFS and you can change it! For instance, if you want there to be a new line when you typecast the array then set $OFS = "`r`n" which will make a newline between every field. If you want to comma separate the values, then set $OFS = ", "

Just remember to clean up when you are done! You can set the value back to it’s default (a single space) by removing the variable: Remove-Variable OFS Don’t worry, PowerShell will remake it.

NOTE: The ‘ that you are seeing should be the Backtick key found to the left of your numbers on a US keyboard.

Enjoy!

Quick Tip: Tab Complete in PowerShell

 Quick Tips  No Responses »
Feb 022011
 

As you are typing in any given PowerShell console or in PowerShell ISE you can finish typing many things simply by hitting the “Tab” key while you are halfway through a word. This practice is refered to as “Tab Complete”. If you aren’t in the practice of using this all the time, then you really need to start utilizing it heavily for your own sake. Not only can it help you type and create code faster, but it can be useful in remembering cmdlet names or parameters when you are typing.

Things I know you can tab complete are: cmdlet names, file and directory names, third party programs, custom scripts, cmdlet parameters, variable names, object members, functions, and many more.

Another cool thing is that if you hit it too early in the word, simply hit it again to keep going through all possible entries. If you type “Get-” and then start hitting tab,you will see the names of all the cmdlets until you get the one you want. Or after you’ve typed the name of a cmdlet,type “-” and then tab to see all possible parameter names, and it even works with your own scripts!

Skipped by the command you wanted? Shift-Tab will start you back in the other direction.

Quick Tip: Insert New Lines and Tabs into PowerShell Strings

 Quick Tips  2 Responses »
Jan 132011
 

Ever wanted to make your output a little cleaner? Try using the built in way of inserting a tab or a new line into your string in PowerShell. It’s an easy way to make your output look much better. All you need to do is add <code>n for a new line or </code>t for a tab.

 

That’s it. By the way, the backtick or backquote that you are seeing is the character to the left one the “1” key on your US formatted keyboard.

Quick Tip: Pi in Windows Powershell

 Quick Tips  No Responses »
Jan 032011
 

It may turn up that you need to use Pi for some random reason. Well instead of trying to make a variable in which you manually type it, you can use the version built into System.Math which holds Pi to 20 decimal places.

$Pi = [System.Math]::Pi
3 * $Pi
>> 9.42477796076938

Quick Tip: Script Parameters in PowerShell

 Quick Tips  3 Responses »
Dec 212010
 

If you are writing a script that you want to (might) use again it can be really useful to use script parameters. PowerShell does some really cool things with parameters that many folks don’t know or realize you can do. This post covers some of those items.

To start us off let’s look at how to use a script parameter.

### Test-Param.ps1 ###
Param($Variable1 = "Hello", $Variable2 = "World")
"$Variable1 $Variable2"

If we save this script and run it we will get an output like this:

>>./Test-Param.ps1
>>Hello World

This simple case shows that our variables are being assigned to the default values. We can change these values by passing them to the script via the command line. These values are passed either in the order that they are sent, or statically assigned by using the variables name.

>>./Test-Param.ps1 "Goodbye"
>> Goodbye World

>> ./Test-Param.ps1 -Variable2 "Universe"
>> Hello Universe

>> ./Test-Param.ps1 "Universe" -Variable1 "Goodbye"
>> Goodbye Universe

As you can see, these are really pretty flexible. Another really cool part of params that you may have noticed by now if you are following along is that these variable names will use tab complete. So if you type “./test-param -” and then start hitting tab, you will cycle through all the names in the param block. If yo haven’t used a script in a long time, then you can quickly see what variables you might want to pass.

Now, sometimes you want to have the param feature, but you need to require the value. You can place some logic after the param block, but I like to just put code straight in there.

### Test-Param.ps1 ###
Param($Variable1 = Read-Host "Please input a value for Variable1",
      $Variable2 = Get-Content $Variable1
"$Variable1"
"$Variable2"

>> ./Test-Param.ps1
>> Please input a value for Variable1: c:ScriptTest.txt
>> c:ScriptTest.txt
>> Hello, World!

>> ./Test-Param.ps1 c:ScriptTest.txt
>> c:ScriptTest.txt
>> Hello, World!

>> ./Test-Param.ps1 c:ScriptTest.txt "Ignore my file"
>> c:ScriptTest.txt
>> Ignore my file

I think that just about covers it for this Quick Tip. Get started converting all your scripts to use a parameter block!

Quick Tip: Entering Object Properties into a String in PowerShell

 Quick Tips  No Responses »
Dec 212010
 

Often times you want to use an object’s specific property to let the user know what’s going on. The problem is that PowerShell won’t allow its dot notation within quotes. When you first try it you might be confused by the results.

$Files = Get-ChildItem
"This directory has $Files.Count files"

>> This directory has Contacts Desktop Documents.Count files

The reason is that PowerShell is only looking for a variable name and ignoring anything else. In this case it is converting all the items held in the $Files variable and displaying it as a string. That makes you tempted to create a variable whose only purpose is to be used in a string on the following line.

$Files = Get-ChildItem
$NumberFiles = $Files.Count
"This directory has $NumberFiles files"

>> This directory has 3 files

This will certainly get you by, but it adds lines of code and variables that won’t be used for anything else. Instead, you can make PowerShell think that you have created a variable simply by surrounding the variable and its dot notation in $() which basically creates a temporary variable which you can work with as you please.

$Files = Get-ChildItem
"This directory has $($Files.Count) files"

>> This directory has 3 files

In this manner you eliminate a useless variable and an excess line of code, but it doesn’t have to stop there. You can even place code blocks inside and really shorten things up. To make our sample code a single line I will use two sets of $(). One to make a temporary variable for Get-ChildItem and one to read the property “Count” and send the output to the string.

"This directory has $($(Get-ChildItem).count) files"

>> This directory has 3 files

Quick Tip: Continuing Code on the Next Line in PowerShell

 Quick Tips  No Responses »
Dec 212010
 

Sometimes your PowerShell code can start to fly off the right side of the screen, especially when you are using commands like write-progress. To space your code down, make it more tidy, and get it to fit on one screen just use the (backtick) key. That’s the ~ (Tilde) key without the shift!

Write-Progress -Activity "Testing New Lines" <code>
-Status "Still Testing" </code>
-CurrentOperation "Testing File $Filename" <code>
-PercentComplete ($Something / $SomethingElse * 100) </code>
-SecondsRemaining $Timer.TotalSeconds