Adding two options to a Powershell script - powershell

Question

Forgive me as I'm still learning powershell so this might be a silly question, but how do I add an options to a .ps1?
For example, I have currently have a script that downloads a file and runs it, but if it cant run it, it will look for the file locally and run it then. How do I separate these two so the user can pick either to download or just run locally?
e.g.:
'./script.ps1 local '
Will look for the file locally and run it
'./script.ps1 external'
will download the file and run it
I'm not sure if functions will be appropriate for this because the point of the script isn't to import it into the modules, I just want it so you run the .ps1.

Answer 1

At the top of your file add;
Param(
[Parameter(Position=1)][string]$option
)
Switch ($option)
{
'local' { RunLocal }
'other' { RunOther }
default { RunDefault }
}
Would look something like
Param(
[Parameter(Position=1)][string]$option
)
function RunLocal {
Write-Host "RunLocal"
}
function RunOther {
Write-Host "RunOther"
}
function RunDefault {
Write-Host "RunDefault"
}
Switch ($option)
{
'local' { RunLocal }
'other' { RunOther }
default { RunDefault }
}

Answer 2

If you need to constrain the values passed to a parameter to a fixed set of values, use the [ValidateSet(...)] parameter attribute:
[CmdletBinding()]
Param(
[ValidateSet('Local', 'External')]
[string] $Option = 'Local'
)
Switch ($Option)
{
'local' {
# ...
break
}
'external' {
# ...
break
}
}
The above defaults -Option (and thus parameter variable $Option) to 'Local', while allowing to pass either Local or External explicitly to -Option - no other values are permitted.