Invoking a script runs the commands inside it. Unless explicitly defined with the GLOBAL scope keyword, variables and functions defined in the script do not persist once the script exits.

You invoke a script by using the invoke/call operator (&) with the script name as the parameter:

& "C:Script DirectoryRun-Commands.ps1" <Parameter List>

You can use either a fully qualified path or a path relative to the current location. If the script is in the current directory, you must explicitly say so:

.Run-Commands.ps1 <Parameter List>

If the path contains no spaces, you may omit both the quotes and invoke operator.

Dot-sourcing a script runs the commands inside it. Unlike invoking a script, variables and functions defined in the script do persist after the script exits.

You invoke a script by using the dot operator (.) with the script name as the parameter:

. "C:Script DirectoryRun-Commands.ps1" <Parameter List>

You can use either a fully qualified path, or a path relative to the current location. If the script is in the current directory, you must explicitly say so:

. .Run-Commands.ps1 <Parameter List>

If the path contains no spaces, you may omit the quotes.

Set-ExecutionPolicy RemoteSigned

To access the command-line arguments by position, use the $args array that is available to all scripts:

$firstArgument = $args[0]
$secondArgument = $args[1]
$argumentCount = $args.Count

param([<TypeName>] $variableName = <Default Value>, ...)

Formal parameters allow you to benefit from some of the many benefits of PowerShell’s consistent command-line parsing engine.

PowerShell exposes your parameter names (i.e.: $variableName) the same way that it exposes parameters in cmdlets. Users need only to type enough of your parameter name to disambiguate it from the rest of the parameters. If the user does not specify the parameter name, PowerShell attempts to assign the input to your parameters by position.

If you specify a type name, PowerShell ensures that the user input is of that type. If you specify a default value, PowerShell uses that value if the user does not provide input for that parameter.

param($mandatory = $(throw "Please input the mandatory parameter."))

To access the data being passed to your cmdlet via the pipeline, use the $input enumerator available to all scripts:

foreach($element in $input)
{
   "Input was: $element"
}

The $input variable is a .NET enumerator over the pipeline input. Enumerators support streaming scenarios very efficiently but do not allow you to access arbitrary elements as you would with an array. If you want to process their elements again, you must call the Reset() method on the $input enumerator once you reach the end.

If you need to access the pipeline input in an unstructured way, the following command converts the input enumerator to an array:

$inputArray = @($input)

When pipeline input is a core scenario of your script, you may include statement blocks labeled begin, process, and end:

param(…)

begin
{
  …
}
process
{
  …}
end
{
  …}

PowerShell executes the begin statement when it loads your script, the process statement for each item passed down the pipeline, and the end statement once all pipeline input has been processed. In the process statement block, the $_ variable represents the current pipeline object.

When you write a script that includes these keywords, all of the commands in your script must be contained within the statement blocks.

The $MyInvocation automatic variable contains information about the context under which the script was run, including detailed information about the command (MyCommand), the script that defines it (ScriptName), and more.

<any command>

The return value/output of a script is any data that the scripts writes to the pipeline. If a script contains the commands,

"Text Output"
5*5

then assigning the output of that script to a variable creates an array with the two values, Text Output and 25.

return <value>

The statement,

return $false

is simply a short form for pipeline output:

$false
return

exit <errorlevel>

The exit statement returns error codes. It sets the $LastExitCode automatic variable to <errorLevel>, which sets the $? automatic variable to $false when <errorLevel> is greater than zero.