about_requires | Easy Powershell 2.0 Reference

SHORT DESCRIPTION
Prevents a script from running by requiring the specified snap-ins and
version.

LONG DESCRIPTION
    The #Requires statement prevents a script from running unless the Windows
    PowerShell version, snap-in, and snap-in version prerequisites are met. If
    the prerequisites are not met, Windows PowerShell does not run the script.

You can use #Requires statements in any script. You cannot use them in
Functions, cmdlets, or snap-ins.

Syntax

Use the following syntax to specify the snap-in and the version of the
snap-in that you want to require:

#requires –PsSnapIn <PsSnapIn> [-Version <N>[.<n>]]

Use the following syntax to specify the minimum version of
Windows PowerShell that you want to require:

#requires -Version <N>[.<n>]

Use the following syntax to specify the shell that you want to require:

#requires –ShellId <ShellId>

Rules for Use

– The #Requires statement must be the first item on a line in a script.

– A script can include more than one #Requires statement.

– The #Requires statements can appear on any line in a script.

Examples

The following statement requires the Microsoft.PowerShell.Security
snap-in:

#requires –PsSnapIn Microsoft.PowerShell.Security

     If the Microsoft.PowerShell.Security snap-in is not loaded, the script
     does not run, and Windows PowerShell displays the following error
     message:

         “The script ‘<script-name>’ cannot be run because the following
         Windows PowerShell snap-ins that are specified by its “#requires”
         statements are missing: Microsoft.PowerShell.Security.”

The following statement requires the Windows PowerShell 2.0 version or
any later version of the Microsoft.PowerShell.Security snap-in:

#requires –PsSnapIn Microsoft.PowerShell.Security –Version 2

The following statement requires Windows PowerShell 2.0 or a later
version:

#requires –Version 2.0

     The following script has two #Requires statements. The requirements
     specified in both statements must be met. Otherwise, the script will not
     run. Each #Requires statement must be the first item on a line:

         #requires –PsSnapIn Microsoft.PowerShell.Security –Version 2
         Get-WmiObject WIN32_LogicalDisk | Out-File K:\status\DiskStatus.txt
         #requires –Version 2

     The following #Requires statement prevents a script from running if the
     specified shell ID does not match the current shell ID. The current
     shell ID is stored in the $ShellId Variable:

#requires –ShellId MyLocalShell