Every script I write has variables in it, but there are different types of variables. This short blog post will show a few types you can use in your scripts.
What are variables?
You can store all types of values in PowerShell variables. For example, store the results of commands and elements used in commands and expressions, such as names, paths, settings, and values.
A variable is a unit of memory in which values are stored. In PowerShell, variables are represented by text strings that begin with a dollar sign ($), such as $a, $process, or $my_var.
Variable names aren’t case-sensitive and can include spaces and special characters.
Array
This is something that I use a lot. An array is a list of items that you can use, for example:
$files=Get-ChildItem -Path d:\temp -Filter *.ps1
This will search for all *.ps1 files in d:\temp and store the found items in the $files array. You can check what type the variable is by adding “.GetType()” behind it. This looks like this:
The BaseType tells you that it’s an Array, and the contents of the Array can be listed by running $files in our example:
C:\Users\HarmV> $files
Directory: D:\Temp
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 29-8-2022 22:24 1481 ﲵ 365healthstatus.ps1
-a--- 25-2-2022 14:30 261 ﲵ Activation.ps1
-a--- 14-7-2022 12:26 4630 ﲵ AdminGroupChangeReport.ps1
-a--- 16-6-2022 13:28 746 ﲵ AdminGroups.ps1
-a--- 26-8-2021 12:49 5455 ﲵ AdminReport.ps1
-a--- 27-10-2021 10:08 14672 ﲵ AppleDEPProfile_Assign.ps1
-a--- 2-11-2021 15:24 9569 ﲵ applevpp_sync.ps1
-a--- 15-10-2020 14:19 2523 ﲵ BIOS_Settings_For_HP.ps1
-a--- 20-1-2022 15:47 142 ﲵ bitlocker.ps1
-a--- 20-1-2022 13:49 64 ﲵ bitlockerremediate.ps1
-a--- 20-1-2022 13:49 192 ﲵ bitlockertest.ps1
-a--- 22-5-2022 21:10 488 ﲵ calendar_events.ps1
...
You can use the array in a ForEach loop to do something to each item in it, for example:
C:\Users\HarmV> foreach ($file in $files) {Write-Host $file.FullName}
D:\Temp\365healthstatus.ps1
D:\Temp\Activation.ps1
D:\Temp\AdminGroupChangeReport.ps1
D:\Temp\AdminGroups.ps1
D:\Temp\AdminReport.ps1
D:\Temp\AppleDEPProfile_Assign.ps1
D:\Temp\applevpp_sync.ps1
D:\Temp\BIOS_Settings_For_HP.ps1
D:\Temp\bitlocker.ps1
D:\Temp\bitlockerremediate.ps1
D:\Temp\bitlockertest.ps1
D:\Temp\calendar_events.ps1
If you want to select a specific item from the array, for example, the second one, you can use: (It starts counting at zero, so the second item is one )
C:\Users\HarmV> $files[1]
Directory: D:\Temp
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 25-2-2022 14:30 261 ﲵ Activation.ps1
You can create an array with your items by running this:
$array=@( "Item 1" "Item 2" "Item 3" )
You can query/view it like this:
C:\Users\HarmV> $array.GetType() IsPublic IsSerial Name BaseType -------- -------- ---- -------- True True Object[] System.Array C:\Users\HarmV> $array Item 1 Item 2 Item 3 C:\Users\HarmV> $array[1] Item 2
Environment variables
These are always available and will contain system or user-specific settings. Examples are: (Type $env: followed by Tab)
C:\Users\HarmV> $env: __COMPAT_LAYER NUMBER_OF_PROCESSORS ProgramFiles(x86) ALLUSERSPROFILE OneDrive ProgramW6432 APPDATA OneDriveCommercial PSModulePath ChocolateyInstall OneDriveConsumer PUBLIC ChocolateyLastPathUpdate OS SystemDrive COLUMNS PARSER_FILES_PATH SystemRoot CommonProgramFiles Path TEMP CommonProgramFiles(x86) PATHEXT TMP CommonProgramW6432 POSH_THEMES_PATH USERDOMAIN COMPUTERNAME POWERSHELL_DISTRIBUTION_CHANNEL USERDOMAIN_ROAMINGPROFILE ComSpec PROCESSOR_ARCHITECTURE USERNAME DriverData PROCESSOR_IDENTIFIER USERPROFILE HOMEDRIVE PROCESSOR_LEVEL windir HOMEPATH PROCESSOR_REVISION WSLENV LOCALAPPDATA ProgramData WT_PROFILE_ID LOGONSERVER ProgramFiles WT_SESSION
You can use this as an example to show the location of your personal or work OneDrive folders:
C:\Users\HarmV> $env:OneDriveCommercial C:\Users\HarmV\OneDrive - NEXXT C:\Users\HarmV> $env:OneDriveConsumer C:\Users\HarmV\OneDrive
It’s system variables you can use in scripts so you don’t hardcode specific paths. It might be that c:\users\public is remapped to d:\users\public, and your scripts will fail if you don’t use the $env:public variable.
Hash table
A hash table is a data structure of key and value pairs. You can create one using the following:
$hashtable=@{
"Android" = "Google"
"iOS" = "Apple"
"MacOS"= "Apple"
"Windows" = "Microsoft"
}
This will look like this:
C:\Users\HarmV> $hashtable Name Value ---- ----- MacOS Apple iOS Apple Windows Microsoft Android Google
You can search for a certain value by using the following to get all values that contain Apple:
C:\Users\HarmV> $hashtable.GetEnumerator().Where({$_.Value -contains 'Apple'})
Name Value
---- -----
MacOS Apple
iOS Apple
Int32/64
You can store numbers in variables, for example:
C:\Users\HarmV> $number=1 C:\Users\HarmV> $number.GetType() IsPublic IsSerial Name BaseType -------- -------- ---- -------- True True Int32 System.ValueType
You can do math with this as well, for example:
C:\Users\HarmV> $number*8 8
You can also add 1 to an existing number variable. I use this to show progress in a script. For example:
$count=1
$files=Get-ChildItem -Path d:\temp -Filter *.ps1
foreach ($file in $files) {
Write-Host ("[{0}/{1}] Found {2}" -f $count, $files.count, $file.fullname)
$count++
}
This will display an output that looks like this:
[1/49] Found D:\Temp\365healthstatus.ps1 [2/49] Found D:\Temp\Activation.ps1 [3/49] Found D:\Temp\AdminGroupChangeReport.ps1 [4/49] Found D:\Temp\AdminGroups.ps1 [5/49] Found D:\Temp\AdminReport.ps1 [6/49] Found D:\Temp\AppleDEPProfile_Assign.ps1 [7/49] Found D:\Temp\applevpp_sync.ps1 [8/49] Found D:\Temp\BIOS_Settings_For_HP.ps1 [9/49] Found D:\Temp\bitlocker.ps1 [10/49] Found D:\Temp\bitlockerremediate.ps1 [11/49] Found D:\Temp\bitlockertest.ps1 [12/49] Found D:\Temp\calendar_events.ps1
String
A string is a simple object with a value, for example:
$string="Hello world"
This is displayed as:
C:\Users\HarmV> $string Hello world
And you can see it’s an object:
C:\Users\HarmV> $string.GetType() IsPublic IsSerial Name BaseType -------- -------- ---- -------- True True String System.Object
You can combine two strings in your output like this:
C:\Users\HarmV> $string2="!" C:\Users\HarmV> Write-Host $string$string2 Hello world!
Or join two strings together like this using -join with the space separator using ” “
C:\Users\HarmV> $string1="Good" C:\Users\HarmV> $string2="Evening" C:\Users\HarmV> $string1,$string2 -join " " Good Evening
But you can also split a string using -split using the “;” character as a delimiter, for example:
C:\Users\HarmV> $string="Hello;world" C:\Users\HarmV> $string -split ";" Hello world
This will output the string in two lines. You can combine those again by using -join:
C:\Users\HarmV> $string -split ";" -join " " Hello world
You can also select a certain range of characters from a string using SubString, for example:
C:\Users\HarmV> $string="Hello world" C:\Users\HarmV> $string.SubString(0,5) Hello
And you can search/replace words in a string using the replace method, for example:
C:\Users\HarmV> $string="Hello world"
C:\Users\HarmV> $string.Replace('Hello','Goodbye')
Goodbye world
A simpler way to join strings is: $string3=”$string1 $string2″
PS > $string3
Good Evening
So many options, I always try to avoid using to many variables 😉
Super helpful tips. Thanks
No problem 😊