You can't do it from the command line, you have to write some code. I assume your application has all the required permissions to do it (examples are without any error checking).
Hard Way
First get all the threads of a given process then call the SuspendThread function to stop each one (and ResumeThread to resume). It works but some applications may crash or hung because a thread may be stopped in any point and the order of suspend/resume is unpredictable (for example this may cause a dead lock). For a single threaded application this may not be an issue.
void suspend(DWORD processId)
{
HANDLE hThreadSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0);
THREADENTRY32 threadEntry;
threadEntry.dwSize = sizeof(THREADENTRY32);
Thread32First(hThreadSnapshot, &threadEntry);
do
{
if (threadEntry.th32OwnerProcessID == processId)
{
HANDLE hThread = OpenThread(THREAD_ALL_ACCESS, FALSE,
threadEntry.th32ThreadID);
SuspendThread(hThread);
CloseHandle(hThread);
}
} while (Thread32Next(hThreadSnapshot, &threadEntry));
CloseHandle(hThreadSnapshot);
}
Please note that this function is even too much naive, to resume threads you should skip threads that was suspended and it's easy to cause a dead-lock because of suspend/resume order.
Undocumented way
Starting from Windows XP there is the NtSuspendProcess but it's undocumented. It should be stable but if you feel worry to use an undocumented function (and I agree to feel worry if there is any other alternative) you may use the next solution. Read this post for a code example (reference for undocumented functions: news://comp.os.ms-windows.programmer.win32).
typedef LONG (NTAPI *NtSuspendProcess)(IN HANDLE ProcessHandle);
void suspend(DWORD processId)
{
HANDLE processHandle = OpenProcess(PROCESS_ALL_ACCESS, FALSE, processId));
NtSuspendProcess pfnNtSuspendProcess = (NtSuspendProcess)GetProcAddress(
GetModuleHandle("ntdll"), "NtSuspendProcess");
pfnNtSuspendProcess(processHandle);
CloseHandle(processHandle);
}
"Debugger" Way
To suspend a program is what usually a debugger does, to do it you can use the DebugActiveProcess function. It'll suspend the process execution (with all threads all together). To resume you may use DebugActiveProcessStop.
This function lets you stop a process (given its Process ID), syntax is very simple: just pass the ID of the process you want to stop et-voila. If you'll make a command line application you'll need to keep its instance running to keep the process suspended (or it'll be terminated). See the Remarks section on MSDN for details.
void suspend(DWORD processId)
{
DebugActiveProcess(processId);
}
From Command Line
As I said Windows command line has not any utility to do that but you can invoke a Windows API function from PowerShell. First install Invoke-WindowsApi script then you can write this:
Invoke-WindowsApi "kernel32" ([bool]) "DebugActiveProcess" @([int]) @(process_id_here)
Of course if you need it often you can make an alias for that.
