Work with hash tables in Windows PowerShell scripts

  • 5 minutes

Working with hash tables is similar to working with an array, except that to add items to a hash table you need to provide both the key for the item and the value. The following command creates a hash table named $servers to store server names and IP addresses:

$servers = @{"LON-DC1" = "172.16.0.10"; "LON-SRV1" = "172.16.0.11"}

Notice the following syntax in the previous example:

  • It begins with the at (@) symbol.
  • The keys and associated values are enclosed in braces.
  • The items are separated by a semicolon.

Note

The semicolon between hash table items is required in the previous example because they're all on the same line. If you place each item on a separate line, it's not necessary to use semicolons as separators.

Adding or removing items from a hash table is similar to an array list. You use the methods Add() and Remove(). For example:

$servers.Add("LON-SRV2","172.16.0.12")
$servers.Remove("LON-DC1")

You can also add or update a value using array notation:

$servers["LON-SRV3"] = "172.16.0.13"

Note

The Add() method throws an error if the key already exists. Array notation silently updates the value instead of throwing an error, making it more suitable when you're not sure whether a key already exists.

You can also update the value for a key. For example:

$servers."LON-SRV2"="172.16.0.100"

To review all properties and methods available for a hash table, use the Get-Member cmdlet. For example:

$servers | Get-Member