CODE EXAMPLE FOR C

reattach screen linux

-d -r   Reattach a session and if necessary detach it first.

-d -R   Reattach a session and if necessary detach or  even  create  it
               first.

-d -RR  Reattach  a  session  and if necessary detach or create it. Use
               the first session if more than one session is available.

-D -r   Reattach a session. If necessary  detach  and  logout  remotely
               first.