How can I move a window to another session in tmux?

In tmux, how can I move a window from a session to another session?

ex. move window:4 in session [0] to session [4] .

From my testing on tmux 2.6, you'll need two things for the command to move an entire window over:

• The name of the session you want to move the window from (for future reference, $session_name)
• The index of the window you want to move (in the session it's currently in, of course -- we'll call this $window_index). This is actually optional -- if you omit this, then it defaults to the window in focus in the session you're pulling the window from.

From this point, you can just change to the session you want to move the window into, <tmux-escape>: into a command prompt, and type a command of this form:

move-window -s $session_name[:$window_index]

...where, as noted before, the $window_index is optional (as indicated by the square brackets, which aren't actually part of the syntax ). To use some concrete examples:

# Moves from currently-focused window from session named `$session_name`
move-window -s $session_name 

# Moves from window with index `$window_index` from 
# session named `$session_name` into the current session
move-window -s $session_name:$window_index

Et voilà! Your window got moved. :)