Powershell ForEach Loop Statement Tutorial with Examples

ForEach is a PowerShell statement used to use iterate or loop over the given list, array or collection of the objects, strings, numbers, etc. ForEach is a very popular loop mechanism where we can use different cases like loop through files, Numbers, Strings, Processes, etc. Powershell version 4.0 brings some performance improvements to the ForEach loop.

PowerShell ForEach Syntax

Foreach statement has the following syntax where we use ITEM, COLLECTION and CODE-BLOCK.

ForEach(ITEM in COLLECTION)
{
   CODE BLOCK
}

• ITEM is a single value or object which changes over each iteration.
• COLLECTION is an array, collection, list of values, or objects like 1,2,3,4.
• CODE BLOCK is the block where the real operation runs which generally uses ITEM. This block can be single or multiple lines.

Foreach Through An Array Of Strings

In a simple way, we can iterate over the given list of the string array. We iterate over the array named “cities” that holds multiple city names. We will print each city name with the command “echo” like below.

$cities = ("istanbul,ankara,canakkale")

foreach ($city in $cities){ echo $city}

We can see that every city name is printed to the powershell terminal in a single line.

Foreach Through An Collection Of Numbers

In the previous example, we have looped over a given list of strings. We can also iterate or loop through a list of numbers. We will create an array named numbers and iterate over each item in this number array.

$numbers=(1,2,3,4,5)
foreach ($number in $numbers){ echo $number}

$_ Usage

When using some cmdlets to redirect the output of cmdlet to the Foreach we can use “$” for each item or object. For example, if we use “Get-Process” cmdlet each item or process will be assigned to the $ in each iteration. We can specify the attribute like Name $.Name  and print like below.

PS> Get-Process | ForEach-Object {$_.ProcessName}

We can also print multiple attributes in foreach by delimiting them with comma.

PS> Get-Process | ForEach-Object {$_.ProcessName, $_.ID}

Foreach Through Files

We can also loop through files by using Get-ChildItem cmdlet. Get-ChildItem will list files and folders like dir MSDOS command. This output will be written to console with the Echo command.

foreach($file in Get-ChildItem) {Echo $file}

Foreach Through Specific File Extensions Like Bat

We can specifically list the specified extension. The extension will generally provide the file type like text, avi, mkv, mp3, doc etc. In this example, we will list only *.bat or Bat files.

 foreach($file in Get-ChildItem *.bat) {Echo $file}

We can see that only files like test.bat and autoexec.bat will be listed.

Foreach Over CSV File

CSV files are used to store text data in a structured manner. We can easily foreach in each line of a CSV file like below. In this example, we will read an IP CSV file and provide to the foreach to print Powershell console.

$IPs = (Get-Content IP.csv)[0].split(",")
foreach ( $IP in $IPs){
    echo $IP
}