GNU screen - Unable to reattach to screen after lost connection

Question

I was using irssi in screen but lost connection. After I ssh'd back in to the server, I can no longer attach to that screen. screen -ls shows that the screen is already attached.

I tried screen -D to force detach it, and it said detach but screen -ls still says it's attached. I tried screen -x and it just hangs there.

[sub@server ~]$ screen -ls 
There are screens on:
 4033.poe (Detached)
 7728.irssi (Attached)
2 Sockets in /var/run/screen/S-sub.

What can I do now?

Answer 1

I have cleared this behavior up in the past by killing the shell that started the screen session. Basically, killing all bash instances for my user that were not owned by screen.

Answer 2

You gave it a non-default name. Try this: screen -RD irssi

Answer 3

If you are trying to connect the 'Attached' screen, then run screen -xr irssi. The uppercase '-X' sends a command to one of the screen sessions, the lowercase '-x' option allows you to reconnect to an attached session. But you still need to give the session name since there is more than one.

Answer 4

I have had some success by sending the GNU/screen process a SIGCHLD (which it normally receives when a window is closed), this forces it to touch (and possibly recreate) the socket file.

Also note that there are two ways to invoke the screen executable that only differ in case: SCREEN is the server-side component you are attempting to reconnect to, while screen is the client-side that shuffles data between your terminal and the server-side. So you might want to try killing the lower-case version...

For instance in the following you can see that my screen and SCREEN processes are not considered to be parent and child, indicating that I have attached to an existing session.

# ps fao pid,command
25070 SCREEN -U
25071  \_ vim +let &t_Co=256
25073  \_ -bash
25077  \_ -bash
...
18364  \_ sshd: username [priv]
18366  |   \_ sshd: username@pts/17
18367  |       \_ -bash
  870  |           \_ screen -U -x

Fresh sessions look more like this:

19645  |  \_ screen -S MySession
19646  |      \_ SCREEN -S MySession
19647  |          \_ bash
 1485  |          |   \_ python
19700  |          \_ bash