process management

steve64

How can I start an external process (.exe) from a LuaRT app, and keep such subprocess running,
but getting its PID after started so that I can kill it later, e.g. by the taskkill Windows command ?

Samir

Your only choice for now is sys.cmd() but it doesn't provide any process control mechanism.
LuaRT 1.9.0 sysutils module contains a Process object that you can use this way :

local sysutils = require "sysutils"

local p = sys.Process("notepad.exe")

p:start()

-- sleeps for 3sec
sleep(3000)

-- call abort method to force process to close
p:abort()

steve64

Thanks, I tried the new sysutils.Process() API in LuaRT 1.9.0 and works fine!

steve64

But it seems that the abort() method applied to the Process instance or even the cancel() method applied to the associated Task instance, as returned by start() do NOT actuallly terminate the actual subprocess (maybe a "force" option is missing?).
By the time being, I partially overcame the issue using:
sys.cmd('taskkill /f /im '..exe_name)
but in my application I spawn multiple instances of same exe so I need a better way.
Your abort() method, if working, would be fine.

Also, getting an exit code in case of errors when calling start() instead of plain nil would be helpful.

Samir

steve64 Also, getting an exit code in case of errors when calling start() instead of plain nil would be helpful.

You can use sys.error() to get the error message

Samir

I know this problem. I have fixed this internally and will be available in the final LuaRT 1.9.0 release

steve64

ok, many thanks