Bukkit

Hello, i want to do this:

save:
  command: /save
  type: RUN_CONSOLE
  runcmd:
    - '$Script$%if%$arg1==flush'
    #- 'minecraft:save-all flush'
    - "$broadcasttext$&8[&7Server&8] &9(Flushing) Saving all server data. . ."
    - '$Script$%elseif%$arg1==on'
    #- 'execute store success score sucess output saveon run save-on'
    - "$broadcasttext$&8[&7Server&8] &9Saving is on"
    - '$Script$%elseif%$arg1==off'
    #- 'execute store success score sucess output saveoff run save-off'
    - "$broadcasttext$&8[&7Server&8] &cSaving is off."
    - '$Script$%else%'
    #- 'minecraft:save-all'
    - "$broadcasttext$&8[&7Server&8] Saving all server data. . ."
  permission-required: true
  register: true
  tablist:
    1:
     - flush
     - all
     - on
     - off

It works, but i want to store the result of /save-on and /save-off
And make a custom message for when it's already enabled or disabled.
I can make this with execute store success but how can i make it variable to use it in a %if%??

Also, if using an $arg as a player name, how can i check if it's online?

(Update):

$Script$%if%$CheckPlayerStatus%$arg2%isOnline%==true

And can i target offline players?, obtain the UUID based on given name?

hOW CAN I KNOW IF COMMAND HAS BEEN GIVEN ARGUMENTS???