My Function will Shut Down or Start Up Multiple VMs - function

Question

I am writing this function to ask a user what VM they want to use, they will have to choose from their own Hyper-V list. After that, it will then ask if I want it on or off. I can get the selected VM to turn on or off when I select it. However, when I run the function it will try to go through all the VM's in Hyper-V. How can I get it so it can just turn on or off the VM I want?
(I am also going to go back and add an option to save the VM if it is on.)
Function get-ORS {
param ($R, $O, $S, $name, $off, $on)
$name= Read-Host "What VM would you like to turn on use?"
$IO= Read-Host "Would you like to turn on/off your VM?: [On] [Off]"
$R= Get-VM | where {$_.State -eq 'Running'}
$O= Get-VM | where {$_.State -eq 'Off'}
$S= Get-VM | Where {$_.State -eq 'saved'}
$Off= Get-VM | where {$_.state -eq 'Running'} | Stop-VM
$on= Get-VM | where {$_.State -eq 'Off'} | Start-VM
if ($IO -eq $on) {
try
{
Start-VM -Name $name
}
catch
{
echo ("Could not start" + $name)
}
}
elseif ($O){
try
{
Start-VM -Name $name
echo ("Starting "+ $name)
}
catch
{
echo "Could not start the VM."
}
}
elseif ($R){
try
{
echo "Your VM is currently running."
}
catch
{
echo "Something went wrong."
}
}
elseif ($S) {
try
{
Start-VM -Name $name
echo ("Starting your from a saved state " + $name)
}
catch
{
echo "Could not start the saved VM."
}
}
if ($IO -eq $off){
try
{
Stop-VM -Name $name
}
catch
{
echo ("Could not turn off " + $name)
}
}
}

Answer 1

There is a lot wrong with this function / script. Especially regarding the logic (use case) and construct side of this effort. It's really a Frankenstein this, meaning, maybe, you are copying and pasting from different sources. The formatting makes this hard to follow as well.
You really need to step back an approach this one use case at a time to make sure you are going down the right path.
You have params, then more prompts for the same information. You have a variable in an if statement that is not in your param or prompt section so it will always be empty.
You are specifically asking for all VMs, ...
$R = Get-VM | where {$_.State -eq 'Running'}
$O = Get-VM | where {$_.State -eq 'Off'}
$S = Get-VM | Where {$_.State -eq 'saved'}
$Off = Get-VM | where {$_.state -eq 'Running'} | Stop-VM
$on = Get-VM | where {$_.State -eq 'Off'} | Start-VM
... but you are saying you only want one, but in your prompts you are asking for two.
$name = Read-Host "What VM would you like to turn on use?"
$IO = Read-Host "Would you like to turn on/off your VM?: [On] [Off]"
You also have these as params, so that's just odd. Only put in the param block what you want to pass or prompt for.
Why do you have a pram block, then have a bunch of Read-Host blocks?
That is redundant. You can do the Read-Host in the Param block as well. So, that you can pass the params all at once, or if one forgets to, prompts occur.
param
(
$name = (Read-Host "What VM would you like to turn on use?"),
$IO = (Read-Host "Would you like to turn on/off your VM?: [On] [Off]")
)
$R = Get-VM | where {$_.State -eq 'Running'}
$O = Get-VM | where {$_.State -eq 'Off'}
$S = Get-VM | Where {$_.State -eq 'saved'}
$Off = Get-VM | where {$_.state -eq 'Running'} | Stop-VM
$on = Get-VM | where {$_.State -eq 'Off'} | Start-VM
You can also, use a validate set to ensure the user only can select an option vs having then type it in.
You can also just show a list of VM's for the use to select from, by using dynamic parameter set or using Out-GridView for the user to select from.
You have a very long if statement which just a candidate for a switch statement to make it more concise.
You are passing all your guest names in your if statements. Why, when you say you only want one.
This comes off as this is all new to you. Which is fine, but t is worth taking a few quick free online session before jumping in. If that is the case then, see these discussions and Q & A's.
See these resources.
PowerShell Resources
Helping out someone with PowerShell
And this...
MS PowerShell Docs
IMHO, you should approach this a different way to make it more concise, easier to understand, extend, maintain and troubleshoot.
What you have could really be reduced to just this, from what you show now. Again, there are many ways to do X or Y, this is just one way.
Function Get-Ors
{
[cmdletbinding()]
[Alias('ors')]
param
(
)
$VMName = ( Get-VM |
Select-Object -Property Name, State, Status |
Out-GridView -OutputMode Single -Title 'Select a target VM you want to use.')
$IO = ( 'On','Off'|
Out-GridView -OutputMode Single -Title 'Select On or Off to start or stop the target VM.')
switch ($IO)
{
On {
"Attempting to start $($VMName.Name)"
Start-VM -Name $VMName
}
Off {
"Attempting to stop $($VMName.Name)"
Stop-VM -Name $VMName.Name
}
default {Write-Warning -Message "$($VMName.Name) state could not be determined"}
}
}
PowerShell will auto generate a response based on current state if not valid for the request.
If you don't care for the built-in Out-GridView, you could construct and use messagebox or WinForm or WPF or use PowerShell other PoorMan's GUI approach, using the Show-Command cmdlet. The PoorMan's GUI approach is not customizable.