' mutex sample
'
' Windows10 x64 22H2 + FreeBASIC 1.10.1 32bit

#include once "windows.bi"

Const mutex_name = "MyProgramName"

Dim As HANDLE hMsp

hMsp = CreateMutex(NULL, TRUE, strptr(mutex_name))
If hMsp <> 0 Then
    Dim As DWORD ret = GetLastError()
    If ret = ERROR_ALREADY_EXISTS Or ret = ERROR_ACCESS_DENIED Then
        ' Already
        Print "Already running. Exit."
        ReleaseMutex(hMsp)
        CloseHandle(hMsp)
        end
    End If
End If

Print "Running ... "
Print "Push Any Key"
sleep

ReleaseMutex(hMsp)
CloseHandle(hMsp)