How to use Import-CSV in PowerShell

When working with PowerShell we can use CSV files to import data into systems or to use it as a reference list, of users, for example, to update or get settings. To do this we use the Import-CSV function in PowerShell.

The Import-CSV function converts the CSV data into a custom object in PowerShell. This way we can easily walk through each row of the CSV file and use the data in our scripts.

In this article, we are going to take a look at how to read a CSV file with PowerShell, using the Import-CSV function, and how to read each line with the foreach cmdlet. I will also give you some tips on how to use the Import CSV function.

PowerShell Import-CSV

The Import-CSV cmdlet is pretty straightforward and only has a few properties that are useful:

• Path – (Required) Location of the CSV file
• Delimiter – Default comma, but this allows you to change it
• Header – Allows you to define custom headers for the columns. Used as property names
• UseCulture – Use the default delimiter of your system
• Encoding – Specify the encoding of the imported CSV file

We are going to start with a simple list of users that we can import in PowerShell. I have created the following CSV file that I will use in the examples below:

UserPrincipalName,"DisplayName","Title","UserType","IsLicensed"
[email protected],"Lee Gu","jr engineer","Member","True"
[email protected],"Megan Bowen","recruiter","Member","True"
[email protected],"Grady Archie","sr engineer","Member","True"
[email protected],"Miriam Graham","Director","Member","True"
[email protected],"openmailbox",,"Member","False"
[email protected],"Johanna Lorenz","Senior Engineer","Member","True"
[email protected],"Joni Sherman","recruiter","Member","False"
[email protected],"Alex Wilber","Marketing Assistant","Member","True"
[email protected],"Isaiah Langer","Sales Rep","Member","True"

This CSV file already had headers for each column, so we don’t need to worry about that for now. To import this CSV file into PowerShell we can simply use the following command:

Import-CSV -Path c:\temp\test.csv | ft

In this case, we don’t store the results into a variable, but immediately output it into a table with ft. As you can see, we now have all our users with all columns nicely in PowerShell.

If you store the results of the import cmdlet into a variable, then you can reference each column as a property using the column name (header):

$users = Import-Csv -Path c:\temp\test.csv
$users.DisplayName

Specifying the Delimiter

A common issue when it comes to import a CSV file with PowerShell is that the delimiter is not recognized. By default, the Import-CSV cmdlet uses the , as the delimited. But here in the Netherlands for example, is the default delimiter in Excel for CSV files is ;.

So when I create in CSV file in Excel that I want to use in PowerShell, I will need to either change the delimiter in the CSV file or specify the correct delimiter in PowerShell. There are two options for this.

We can use the -delimiter parameter to specify the correct delimiter:

$users = Import-Csv -Path c:\temp\test.csv -Delimiter ;

Or use the system default delimiter with the -UseCulture parameter:

$users = Import-Csv -Path c:\temp\test.csv -UseCulture

If you want to know what the default delimiter is on your computer, then you can use the following PowerShell command to get the culture information:

(Get-Culture).TextInfo.ListSeparator

Powershell Import CSV ForEach

Most of the time when you import a CSV file in PowerShell you want to walk through each line of the CSV file. For example to get the mailbox permissions or OneDrive folder size.

To do this we can combine the Import CSV cmdlet with ForEach. Inside the ForEach block, we can reference each column of the CSV file as a property of the user object in this case.

Taken the CSV file example that I have added at the beginning of the article, we can get the mailbox of each user using the UserPrincipalName like this:

Import-CSV -Path C:\temp\test.csv | ForEach {
    # Get mailbox of each user
    Get-ExoMailbox -identity $_.UserPrincipalName
}

For this to work your CSV file will need to have headers. That is not always the case, sometimes CSV files only contain values and no headers at all.

To still be able to reference each value in the CSV file you will need to add headers to the Import-CSV file cmdlet.

Adding Headers to Import-CSV

Let’s take the following CSV file with server names and the IP Address of the server:

la-ams-ad01,10.15.0.1
la-ams-file02,10.15.0.3
la-ams-db01,10.15.0.4
la-osl-ad01,10.12.0.1
la-osl-file01,10.12.0.5

As you can see, this CSV file doesn’t have headers (column names). So when we import this CSV file directly in PowerShell you will see that the first row is used as the header. This is not going to work.

So what we need to do is define the headers for the CSV file. We will need to list all headers in a comma-separated string, enclosing each header name with single quotes ' .

Import-Csv -Path c:\temp\server.csv -Header 'ServerName','IpAddress'

Important to know is that if you don’t specify all headers, the remaining columns are not imported. So if we expand our CSV file with the following columns:

la-ams-ad01,10.15.0.1,HP,DL365 G10
la-ams-file02,10.15.0.3,HP,DL380 G9
la-ams-db01,10.15.0.4,HP,DL385 G10
la-osl-ad01,10.12.0.1,HP,DL110 G8
la-osl-file01,10.12.0.5,HP,DL345 G10

And only specify three column headers, then the last column, server model in this case, won’t be imported:

Import-Csv -Path c:\temp\server.csv -Header 'ServerName','Ip','Brand'

# Result:
ServerName    Ip        Brand
----------    --        -----
la-ams-ad01   10.15.0.1 HP
la-ams-file02 10.15.0.3 HP
la-ams-db01   10.15.0.4 HP
la-osl-ad01   10.12.0.1 HP
la-osl-file01 10.12.0.5 HP

If you define more headers than that there are columns, then an additional empty property is created for each object. This can be useful if you want to create an object with additional fields that you want to fill later on. For example, if you want to look up the disk space of each server, we can already add the disk space column to the imported data:

Import-Csv -Path c:\temp\server.csv -Header 'ServerName','Ip','Brand','Model','DiskSpace' | ft

# Result
ServerName    Ip        Brand Model     DiskSpace
----------    --        ----- -----     ---------
la-ams-ad01   10.15.0.1 HP    DL365 G10
la-ams-file02 10.15.0.3 HP    DL380 G9
la-ams-db01   10.15.0.4 HP    DL385 G10
la-osl-ad01   10.12.0.1 HP    DL110 G8
la-osl-file01 10.12.0.5 HP    DL345 G10

This allows to do the following for example:

$servers = Import-Csv -Path c:\temp\server.csv -Header 'ServerName','Ip','Brand','Model','DiskSpace'

$servers | ForEach {
    $_.DiskSpace = Invoke-Command -ComputerName $_.ServerName {Get-PSDrive C} | Select-Object Free
}

How to Import only specific fields with Import-CSV

When you import a CSV file into PowerShell it will import all the columns by default. But when working with large files it can be useful to only select the data that you really need.

There are two ways to do this, if your CSV file has headers, then you can select only the column that you need:

Import-Csv -Path c:\temp\test.csv | select DisplayName,Title | Ft

Another option is to use the -header parameter, but this only works well when you only need the first column (or the first couple of columns). Because you can’t skip a column with this method:

Import-Csv -Path c:\temp\test.csv -Header id

# Result
id
--
UserPrincipalName
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]

Wrapping Up

The Import-CSV cmdlet in PowerShell is really useful when you need to work with lists or want to look up multiple entities. Make sure that you check if the CSV file comes with headings and that you use the correct delimiter.

If you have any questions, then just drop a comment below.