Is it possible to change GNU screen session name after created?

Solution 1:

Use Ctrl-a: to get to command mode for the session and then use the sessionname command

sessionname session1

EDIT:

Using your example above:

If you are detached from a session you can change it's session name with

screen -r 25278.pts-15.linux-ic37 -X sessionname YourSessionName

If you are attached to the session then you can change it's session name with

screen -d -r 25134.pts-3.linux-ic37 -X sessionname YourSessionName