Question

How would you check if a WIN32 service exists and, if so, do some operation?

Answer 1

Off the top of my head, you can check if a specific service is running, as mentioned by bmargulies, using the “net” command, piping the result into “find”.
Something like the following would check if a service was running, and if so stop it. You can then start it without worrying about if it was already running or not:

net start | find "SomeService"
if ERRORLEVEL 1 net stop "SomeService"
net start "SomeService"

If you’re using findstr to do a search, as some of the other answers have suggested, then you would check for ERRORLEVEL equal to 0 (zero)… if it is then you have found the string you’re looking for:

net start | findstr "SomeService"
if ERRORLEVEL 0 net stop "SomeService"
net start "SomeService"

Essentially most DOS commands will set ERRORLEVEL, allowing you to check if something like a find has succeeded.