This sucks.

$ tmux attach-session
no sessions

My sysadmin upgraded tmux and now I can't reattach. My processes are still running according to ps ux. Is there any hope of recovering my session?

Update: There's a socket in /tmp/tmux-1234, so I tried tmux -L /tmp/tmux-1234/default attach, but tmux does nothing. Hooray.


This quickest way to determine if you can recover is:

killall -10 tmux

That will send the signal to recreate all socket files for any running tmux processes. If you're not root, no problem it will only signal your tmux process anyway.

Long story short, if tmux is not running (ps xu | grep tmux), you're screwed :(

  • 3
    This works, but I was confused about why it works. It turns out that signal 10 is a user-defined signal, and tmux says it will "recreate the server socket on SIGUSR1". – DaoWen Jan 19 '15 at 19:47
  • As it might help others: I had to find the PID of the tmux process running my lost session and do kill -10 "PID". – user35915 Mar 26 '18 at 7:35
  • 1
    (1) Thanks for this answer, it saved me a ton of work :) (2) I think it would be helpful to mention that the messages you get when another user is also running tmux, namely tmux(12345): Operation not permitted, are expected. – David Z Jul 2 '18 at 18:38
  • @DaoWen according to man signal (7), the signal value 10 does correspond to SIGUSR1, so all is well – spinup Feb 16 '19 at 2:08

tmux is not guaranteed to be compatible across updates; ask your sysadmin to let you know before doing upgrades or use a copy you built locally that he is less likely to mess with.

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