What does the period '.' operator do in powershell?

Question

This is a weird one. Normally when I execute an external command from powershell I use the & operator like this:

& somecommand.exe -p so         


        

Answer 1

The Short: It is a Special Operator used to achieve what regular operators cannot achieve. This particular operator . actually has two distinctively different Special Operator use cases.

The Long:

As with any other language, scripting or otherwise, PowerShell script also supports many different types of Operators to help manipulate values. These regular operators include:

• Arithmetic
• Assignment
• Comparison
• Logical
• Redirection
• List item
• Split and Join
• Type
• Unary

However, PowerShell also supports whats known as Special Operators which are used to perform tasks that cannot be performed by the other types of operators.

These Special Operators Include:

• @() Array subexpression operator
• & Call operator
• [ ] Cast operator
• , Comma operator
• . Dot sourcing operator
• -f Format operator
• [ ] Index operator
• | Pipeline operator
• . Property dereference operator
• .. Range operator
• :: Static member operator
• $( ) Subexpression operator

. Dot sourcing operator: is used in this context to allow a script to run in the current scope essentially allowing any functions, aliases, and variables which has been created by the script to be added to the current script.

Example:

. c:\scripts.sample.ps1 

NoteThat this application of the . Special Operator is followed by a space to distinguish it from the (.) symbol that represents the current directory

Example:

. .\sample.ps1

. Property dereference operator: Allows access to the properties and methods of of an object which follows the . by indicating that the expression on the left side of the . character is an object and the expression on the right side of the is an object member (a property or method).

Example:

$myProcess.peakWorkingSet  
(get-process PowerShell).kill()

Disclaimer & Sources:

I had the same question while looking at a PowerShell script that I was trying to expand on its feature sets and landed here when doing my research for the answer. However I managed to find my answer using this magnificent write up on the Microsoft Development Network supplemented with this further expansion of the same ideas from IT Pro.

Cheers.