Sending keys to an open windows in PowerShell

Question

I made a program that opens a certain program, then Ctrl+C it after x amount of time.

I am now using this [System.Windows.Forms.SendKeys]::SendWait("^{c}"). Will this target that certain window or just randomly send it to the current window?

How can I change it to a certain window?

This is my code:

Write-Host "Safe Botting V0.1"
Write-Host "Initializing..."
Start-Sleep -s 3
Write-Host "Program started successfully with no errors."

While($true)
{
    Write-Host "Starting bot..."
    Start-Sleep -s 3
    Start-Process -FilePath E:\Documents\bot.exe
    Write-Host "Bot started successfully"
    $rnd = Get-Random -Minimum 1800 -Maximum 10800
    Write-Host "The bot will run for:"
    Write-Host $rnd
    Start-Sleep -s $rnd
    Write-Host "Bot will now stop!"
    [System.Windows.Forms.SendKeys]::SendWait("^{c}") 
    Write-Host "Bot terminated"
    Write-Host "Starting cooldown time"
    $rnb = Get-Random -Minimum 14400 -Maximum 28800
    Write-Host "The bot will cooldown for"
    Write-host $rnb
    Start-Sleep -s $rnb
    Write-Host "Cooldown Finished, Restarting"
    Start-Sleep -s 5
}

What are you actually trying to achieve here? This sounds like an [XY problem](http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem); I suspect there's a cleaner solution to your problem, e.g. using the `Taskkill` command. Also, please include your actual code in your post. — Tom Lord, Sep 14 '16 at 09:20
The program im trying to run has to be stopped by Ctrl+C or else it will fail to load next time. — Jelly bean, Sep 14 '16 at 09:29
Then how about the [`Stop-Process`](https://technet.microsoft.com/en-us/library/ee177004.aspx) command? — Tom Lord, Sep 14 '16 at 09:33
Im not so familliar with powerhshell what does Stop-Process do? — Jelly bean, Sep 14 '16 at 09:36
Click the link in the above comment. I'm not going to copy+paste the first paragraph here. — Tom Lord, Sep 14 '16 at 09:39
Please go and try it yourself. We're not here to spoon-feed you a solution. — Ansgar Wiechers, Sep 14 '16 at 09:44
$botid = Start-Process -FilePath E:\Documents\bot.exe -PassThru — Jelly bean, Sep 14 '16 at 10:12
But the problem is it closes it, and then the program cant save like it did with Ctrl + C — Jelly bean, Sep 14 '16 at 10:12
Please look into this topic: http://stackoverflow.com/questions/16017094/handling-a-popup-box-using-powershell They describe here how to activate required window to send your key sequence to. — n01d, Sep 14 '16 at 13:12

score 10 · Accepted Answer · edited May 23 '17 at 12:13

You could send the CTRL_C_EVENT signal to the process if you have the process id. In your case you can get that from Start-Process (read the docs if you don't know how to get the process id). It's also possible to get the process id from a Window Handle:

Find process id by window's handle

Sending the signal is non trivial, but thanks to @Nemo1024, @KindDragon, and Stack Overflow it's been worked out:

Can I send a ctrl-C (SIGINT) to an application on Windows?

Unfortunately, using the best approach I could find also terminated the calling PowerShell process and the only workaround I could come up with was to send the signal from a fresh PowerShell instance that I launch.

In PowerShell it looks something like this:

# be sure to set $ProcessID properly. Sending CTRL_C_EVENT signal can disrupt or terminate a process
$ProcessID = 1234
$encodedCommand = [Convert]::ToBase64String([System.Text.Encoding]::Unicode.GetBytes("Add-Type -Names 'w' -Name 'k' -M '[DllImport(""kernel32.dll"")]public static extern bool FreeConsole();[DllImport(""kernel32.dll"")]public static extern bool AttachConsole(uint p);[DllImport(""kernel32.dll"")]public static extern bool SetConsoleCtrlHandler(uint h, bool a);[DllImport(""kernel32.dll"")]public static extern bool GenerateConsoleCtrlEvent(uint e, uint p);public static void SendCtrlC(uint p){FreeConsole();AttachConsole(p);GenerateConsoleCtrlEvent(0, 0);}';[w.k]::SendCtrlC($ProcessID)"))
start-process powershell.exe -argument "-nologo -noprofile -executionpolicy bypass -EncodedCommand $encodedCommand"

Yes, I know this is VERY ugly.

GeorgesZ · Answer 2 · 2020-11-23T20:29:23.707

Thanks to jimhark, I found a way to make it work without spawning a separate PowerShell process to send the Ctrl-C. It works if the PowerShell process sending the Ctrl-C also spawned, using for example Start-Process, the process it is sending the Ctrl-C to:

$ProcessID = 1234
$MemberDefinition = '
    [DllImport("kernel32.dll")]public static extern bool FreeConsole();
    [DllImport("kernel32.dll")]public static extern bool AttachConsole(uint p);
    [DllImport("kernel32.dll")]public static extern bool GenerateConsoleCtrlEvent(uint e, uint p);
    public static void SendCtrlC(uint p) {
        FreeConsole();
        AttachConsole(p);
        GenerateConsoleCtrlEvent(0, p);
        FreeConsole();
        AttachConsole(uint.MaxValue);
    }'
Add-Type -Name 'dummyName' -Namespace 'dummyNamespace' -MemberDefinition $MemberDefinition
[dummyNamespace.dummyName]::SendCtrlC($ProcessID) }

What made things work was sending the GenerateConsoleCtrlEvent to the desired process group instead of all processes that share the console of the calling process and AttachConsole back to the console of the parent of the current process.

Nice. And more readable. I've not tested this, but it looks good. — jimhark, Jun 02 '21 at 16:17

Sending keys to an open windows in PowerShell

2 Answers2

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