PowerShell – 5 Most Frequently Used Commands/Scripts

PowerShell is a powerful tool that significantly streamlines and simplifies the work of administrators. It allows you to implement hundreds or even thousands of changes with a few-line script. After reading this article, you'll learn which PowerShell commands and scripts are most frequently used. Each command includes an example that you might use or have already used in practice.

ForEach or ForEach-Object Statement

A loop is invaluable for operating on multiple objects. It allows you to perform an action on each object in a given collection. It's worth noting that if you use ForEach at the beginning of a line, it's considered a statement. By placing it after the pipeline, PowerShell treats it as an alias for the ForEach-Object command. In short, these commands differ in speed and memory usage. ForEach is faster, ForEach-Object uses fewer resources. Sounds complicated? In practice, it's much simpler. For example:

#Script that changes the domain in the email addresses of all users in Active Directory. #In this example, ForEach is treated as a separate statement. Import-Module ActiveDirectory #Imports the Active Directory module. #It's necessary to run the Get-ADUser and Set-ADUser commands. $ADusers = Get-ADUser -Filter * #Creates the $ADusers collection. It contains all users in AD. #Foreach loop for the $ADusers collection. Each individual object is designated as $ADuser. foreach ($ADuser in $ADusers) { $email = $ADuser.samaccountname + '@domain.pl' #Create the $email variable. #This variable contains the username with the @domain.pl suffix added. #E.g., for user john.smith, it will be john.smith@domain.pl. Set-ADUser -Identity $ADuser.samaccountname -EmailAddress $email #Set the variable created above as the email address. } #The loop will execute for each user in the $ADusers collection.

and

#Script that changes the domain in the email addresses of all users in Active Directory. #In this example, I'll use ForEach-Object.Import-Module ActiveDirectory #Import the Active Directory module. #It is necessary to run the Get-ADUser and Set-ADUser commands. $ADusers = Get-ADUser -Filter * #Creating the $ADusers collection. The collection contains all users in AD. #Sending the contents of $ADusers to ForEach-Object using the pipeline. #In this case, the $_ variable is used instead of $ADuser to identify a single object in the collection. $ADusers | ForEach-Object{ $email = $_.samaccountname + '@domain.pl' #Creating the $email variable. #The variable contains the username with the @domain.pl suffix added. #e.g., for user john.smith it will be john.smith@domain.pl. Set-ADUser -Identity $_.samaccountname -EmailAddress $email #Setting the variable created above as the email address. } #The loop contents will be executed for each user in the $ADusers collection.

Import-Csv / Export-Csv                      

How limited would PowerShell be without the ability to read and write to files? The Import-Csv / Export-Csv commands are the most frequently used solutions for external data operations. Import-Csv allows you to import data from a CSV file into your script. Similarly, Export-Csv exports the data, saving it in CSV format.

Export-Csv:

#Script that exports a list of processes to a CSV file. $process = Get-Process #Create the $process variable. #The variable contains the list of processes. $process | Export-Csv -Path C:\temp\process.csv #Pass $process via pipeline | to the Export-Csv command. #The Export-Csv command saves the $process variable to C:\temp\ as the process.csv file.

Import-Csv:

#Script for importing phone numbers from a CSV file. Import-Module ActiveDirectory #Import the ActiveDirectory module. #Necessary to run the Set-ADUser command. $NumbersList = Import-Csv -Path C:\temp\numbers.csv #Import the numbers.csv file, located at C:\temp\numbers.csv, to $NumbersList. #Start a foreach loop. #The loop executes for each row in the numbers.csv file. foreach ($Number in $NumbersList){ Set-ADUser -Identity $Number.samaccountname -MobilePhone $Number.telephonenumber #Assigns a phone number from the imported file to the user in AD. }

Plik numbers.csv:

"samaccountname","telephonenumber" "test.user1","145345345" "test.user2","123123123" "test.user3","145445661" "test.user4","125345345" "test.user6","115213721" "test.user7","155345345" "test.user8","176876555" "test.user9","122533345" "test.user10","999999999"

Select-Object

A simple and extremely useful command that selects an object or its properties. The example below selects users who have logged in to their account within the last 30 days. You're interested in the username and last login date. – You can obtain these properties using Select-Object.

#Script that displays the account name and last login date of accounts logged in within the last 30 days. Import-Module ActiveDirectory #Import the Active Directory module. $Date = (get-date).adddays(-30) #Create the $Date variable. #This variable contains the date 30 days ago. Get-ADUser -properties * -filter {(lastlogondate -ge $Date)} | Select-Object samaccountname,lastlogondate #Select accounts whose lastlogondate is later than or equal to $Date. #Using Select-Object, the result will be displayed as: #samaccountname lastlogondate #account1 01/01/2021 01:01:01 #account2 02/01/2021 02:02:02 #...

Where-Object

Using Where-Object, you can select objects of interest based on their attributes. Often, the filter parameter takes over the functionality of the Where-Object command. Using a filter significantly reduces script execution time, but it's not available for every command. In such cases, Where-Object comes in handy.

#Script displaying accounts from the "Test" department Import-Module ActiveDirectory #Import the Active Directory module. Get-ADUser -Filter 'Department -eq "Test"' #Selecting accounts using the -Filter parameter Get-ADUser -Properties Department -Filter * | Where-Object Department -eq 'Test' #Selecting accounts using Where-Object. #In this case, the output of the Get-ADUser command is sent to Where-Object via a pipe.

Get-ChildItem

Get-ChildItem returns files located in the specified locations. You can use this command to search for files or check the properties of interest. Below is an example of use:

#Script displaying the contents of the $path folder, including subfolders. $path = 'C:\test\*.*' #The path variable contains the location to be searched. Get-ChildItem -Path $path -Recurse #With the -Recurse parameter, the contents of the $path folder are searched, including subfolders.

Summary of PowerShell Most Commonly Used Commands

The most frequently used commands vary depending on the IT solutions in the work environment. The above list is based on the experience of an IT administrator working on Windows Server systems. The script examples provided, after testing, can be easily implemented in a production environment. Do you also use PowerShell on a daily basis? Perhaps it's worth considering which commands you use most often?

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