Powershell foreach array of strings

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Powershell foreach array of strings

When you start writing Powershell scripts, you will inevitably come to a point where you need to elaborate more elements of a collection. At that point you will have to dig into the Powershell Loops and learn what it is. Almost all programming languages have a construct called loops; Powershell is not different. One of the most popular types of loops in PowerShell is the Loop Foreach. At its most elementary, a Freach cycle reads an entire collection of elements and foreach items, performs a kind of code. One of the most confused aspects of the Powershell loop for beginners are all available options. There is only one way to process each element of a collection, there are three! In this article, you will learn how every kind of Loop Foreach works and when using it above the other. When you finish with this article, you will have a good knowledge of all kinds of Foreach cycle. Powershell Foreach Loop Basics One of the common Loops types you will use in PowerShell ? ? the type of Loop Foreach. A foreach cycle reads a set of objects (itera) and is completed when it ends with the last one. The collection of objects read is typically represented by an array or a hashtable. Note: The term iteration is a programming term that refers to each execution of a cycle. Whenever a cycle complete a cycle, this is called iteration. The act of performing a cycle on a set of objects is commonly referred to as iteration on the whole. Maybe you need to create a text file in some folders scattered in a file system. Let's say that folder paths are C: Folder, C: Files Folder2 and C: Folder3. Without a loop, we should refer to the Add-Content CMDlet file three times. Add-content -Scerse ? TM C: -Valore ? TM This is the contents of the file 'add-content-arch ? TM c: folder2 textfile.txt' -valore ? TM This is the content of the file 'which is the only one Difference between these references to the commands? It is the value of the route. The value for the route is the only value that changes between each of these. You're duplicating a lot of code. You are losing time to type and open up to the problems at the bottom of the road. Instead, you should create a ?set? that includes all the elements that are changing. For this example, we will use an array. $ folders = @ (? TM C: Folder ', ? TM C: Programs Folder2, ? TM C: Folder3') Now you have each of these paths stored in a single ?set? or array . You are now able to use a loop to iterate on each of these elements. Before you do, though, ? It's a good time to mention a topic that usually stumble in those new PowerShell. Unlike other types of rings, there are no one of the same. Technically, there are three types of foreach loops in PowerShell. Although each similar ? ? Use, it is important to understand the difference. The Foreach Foreach The first type of loop foreach is a statement. Foreach is an internal powershell keyword that is not a cmdlet or a function. Forech education is always used in the form: foreach ($ I in $ array). Using the example above, the $ i variable represents the hyterator or value of each element in $ path as iter on each element in the array. Note that the iterator variable should not be $ i. The variable name can be anything. In the following example, you can perform the same task as repeating the reference of the additional content by doing this: # Create an array of $ folders = @ ('c: \ folder', 'c: \ Program file \ Folder2', 'C: \ FOLDER3') # Run iteration to create the same file in each Foreach folder ($ i in $ folders) {addi-content -path "$ i \ samplefile.txt" -Value "This is the content of the file "} Forech education is known to be a faster alternative than using the foreach cmdlet. The cmdlet of forach objects if forach is an instruction and can only be used in a single way, foreach-object is a cmdlet with parameters that can be used in many different ways. Like Foreach instruction, the cmdlet of foreach objects can isolate on a set of objects. Only this time, it passes this set of objects and the action to take each object as a parameter as shown below. $ folder = @ ('c: \ folder', 'c: \ Program file \ Folder2', 'c: \ folder3') $ folders | Foreach-object (add-content-content -path "$ _ \ samplefile.txt" -Value "This is the content of the file") Note: to make things confused, the cmdlet of foreach objects has an alias called foreach. Depending on how the term ? oeforeach? is called, Forech's claim is executed or Forech-Object object. A good way to differentiate these situations is to notice if the term ? oeforeach? is followed by ($ somavariable in someset). If not, in any other context, the author of the code probably uses the alias for foreach object. The Foreach method () was introduced one of the newest Forech rings for PowerShell V4 called Foreach Method (). This method exists on an object of array or collection. The Foreach method () has a standard script block parameter that contains actions to detect each iteration, just like others. $ folders = @ ('c: \ folder' ',' c: \ Programs \ Folder2 ',' c: \ folder3 ') $ folders. Foceach ({addi-content -Path "$ _ \ samplefile.txt" -Value "This is the content of the file"}) The most significant difference with the Foreach method () is how it works under the hood. The use of the Foreach method () is considerably faster and is significantly so on large sets. We recommend using this method compared to the other two if possible. Mini-Project: looping on a set of server names One of the most common uses for a loop ais reading a number of servers from some source and performing some actions on each of them. For our first mini-project, we build some code that will allow us to read server names (one per line) from a text file and ping each server to determine whether they are online or not. List of server namesA text file for this workflow, what kind of ring do you think would work better? Note that I mentioned the word ? oeTool? as in the server ? ? . This is a clue. You already have a specified number of server names, and you would like to perform some actions on each of them. This sounds like a great opportunity to try the most common Powershell loop used; The leftover cycle. The first activity is to create a set of code server names. The most common way to do it is to create an array. Lucky for us that Get-Content, by default, returns an array with each element in the array represented by a single line in the text file. First, create a series of all my server names and call it $ server. $ servers = Get-content. Servers.txt now that you have created the array, now you will have to confirm if each server is online or not. A large cmdlet to test the connection of a server is called Test-Connection. This cmdlet performs some connection tests on a computer to see if it is online or not. By performing Test-Connection within a predecia loop to read each file line, you can spend each server name represented by the $ Server variable to Test-Connection. This is the way Powershell goes through a text file. You can see an example of how it works below. foreach ($ server at $ servers) {try {$ null = Test-Connection -ComputerName -Count server $ 1 -ErrorAction STOP Write-Output "$ server - OK"} catch {Write-Output "$ server - $ ($ _ .Exception. Message) When the leftover cycle is executed, then something similar will seem: looping test-connection through a list of server names now you have successfully tested a full text file of server names! At this point now you can add or remove the names of the servers in the text file at will without changing the code. you have successfully practiced what we preached, the DRY method. For every power of Shell Examples Let's look at examples of how to use the foreach loop. These are based on real use cases that show the concept that you can modify to meet your needs. This example demonstrates the common use of PowerShell for each folder in a directory. Suppose there are ten UNDERLOAD telle in the folder C: \ ARCHIVE_VOLUMES. Each subfolder is a volume of archive that runs daily. After each backup is complete, a file called BackupState. txt is created within each folder containing the date when it was backed up. You can see an example of how this might appear below. Subdirectory under C: \ ARCHIVE_VOLUMS The following script executes three actions: get the list of all the subfolders within C: \ ARCHIVE_VOLUMESloops through each cartellacrea a text file called BackupState. txt containing the current and time its value The example below is using this statement. # Define the TOP $TOP_FOLDER = "C:\ARCHIVE_VOLUMES" # Get all folders under recurring $Child_Folders = Get-ChildItem -Path $TOP_FOLDER -Recurse | Where-Object {$_.PSIsContainer - Eq Eq} # Create a text file in each subfolder and add the current date and time as a value. Foreach ($ FolderName in $ child_folders.fullName) {(Get-date -format g) | Out-File -FilePath ? ?$ ($ FolderName) Backupstate.txt? -force} Using Get-Childitem cmdlet, you can confirm that the files have been created or updated within each of the subfolders. Get-Childitem -Recurse -Path C: archive_volumes -Include backupstate.txt | SELECT-OBJECT Full name, CreationTime, Lastwritetime, Length The screenshot below shows the script output that displays all backupstate.txt files present in each subdirectory. A text file is created in each subdirectory Example 2: Read the content of each text file in subdirectories later, to demonstrate the use of the Powershell Freach file in a directory, the script below reads each backupstate.txt file created in TM Example 1. Recursively finds all the backupstate.txt files within each subdirectory. Using the Foreach statement, read each text file to get the value ? ?Last backup time?. Show the result on the screen . ## Find all backupstate.txt files in C: archive_volumes $ files = getchilditem -Recurse -Path C: archive_volumes -Include ? TM backupstate.txt '| Select-Object DirectoryName, FullName ## Read the content of each file foreach ($ files in $ files) {Write-output (? ?$ ($ File.DirectoryName) Last Backup Time ? ? ? + (Get-content $ file.fullName))} Once the script is executed in the Powershell session, you should see an output similar to that of the screenshot below. This shows that Powershell passes through the files, reads the contents and view the output. Using Loop Foreach through files and read the content. Example 3: Obtaining services and start using the CMDlet Foreach-Object system System administrators often need to get the status of services and activate a manual or automatic workflow to correct any fault services. Let's look at the sample script using the Foreach-Object cmdlet format. For this example, the script below performs the following operations: Get a list of services configured for an automatic start but not currently running. Include, the elements of the list are directed to the Foreach-Object cmdlet to attempt to start each service. Depending on the result of the Start-Service command, a success or bankruptcy message is displayed. ## Get a list of automatic services stopped. $ services = Get-Service | where-object {$ .Starttype -EQ ? TM automatic '-and $ .Status - Running'} ## passes each object of service to the pipeline and process it with the object Foreach cmdlet $ services | PERAACH-OBJECT {Try {Writing host ? ?Attempt to start '$ ($ .DisplayName)' ? Startup service - $ .Name -Erroraction Stop Write-Host writing ?Success: ' $ ' has been started' } catches { write output ?FAILED: $ ($.exception.message) ? } When the script is executed, it will appear as the output screenshot below. As you can see, every service has been issued a boot command. Some were successfully started, while others failed to start. Use ofLoop To Start Services Example 4: Reading data from CSV using the Foreach method () using CSV file data is popular among system administrators. Putting records within a CSV file simplifies performing mass operations using the combination of import-csv ? and foreach. This combination is commonly used for creating multiple users in Active Directory. In this next example, it is assumed that you have a CSV file with two columns ? "FirstName and lastName. This CSV file should then be populated with the names of new users to create. The CSV file would look like something below. "FirstName", "LastName" "Grimm", "Reaper" "Hell", "Boy" "Rick", "Rude" now for the next script block. First of all, import the CSV file by passing the content path to the import-csv cmdlet. Then, using the Foreach method (), loop through names and create new users in Active Directory. # Import list of FirstName and LastName from CSV File $ NewUsers = Import-CSV -Path.\ Employees.csv Add-type-type -SemblyName System.Web # Proceed list $ NewUSERS. FOREACH ({# Generates a random password $ password = [System.Web.Security.Membersership]:: GeneratePassword ((Get-casuale -Minimum 20 -Maximum 32), 3) $ secpw = ConvertTo-SecureString -String $ Password -AssplointExt -Force # formulate a username name = '{0} Subbstring.Subbstring (0, 1), $ _. Lastname # Build New User Attributes $ NewUserParametrers = @ {CETNAME = $ _. FirstName Surname = $USerName AccountPassword = $ secpw} proof {new-adusor @newuserparameters -erroraction stop write-output input "user name Message) When it is executed, you Now should have created an AD user for each line in the CSV file! The logic behind the PowerShell Foreach cycle is no different from that of other programming languages. Edit only with the way it is used and which loop foreach variation is chosen for any specific task. In this article, you learned the different types of loop foreach available at PowerShell and what to consider from what to use. You also saw the three types of loops foreach in action using different sample scenarios. Further reading

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