See https://github.com/tmux/tmux/wiki/Advanced-Use

### Socket
Tmux by default creates a socket in `/tmp/tmux-$UID/default`.
We can change this
```bash
tmux -Lhello  -- creates/uses server and socket in /tmp/tmux-$UID/hello
tmux -Shello  -- creates/uses server and socket in file 'hello'
```
to see socket path within a session
```
:display -p '#{socket_path}'
```
If a socket is accidentally deleted, it can be recreated via
```bash
pkill -USR1 tmux
```

### Session
```
:kill-session -C  -- clear alert flags
```

### Working directory
By default the working directory is the directory we were in when launching tmux.
This can be changed via
```
:attach -c/tmp
```
Or when creating a new session, window or pane
```
:new -c/tmp    -- new session with working directory /tmp
:neww -c/tmp   -- new window with working directory /tmp
:splitw -c/etc -- new pane (split one above other) with cwd=/etc
:splitw -h -c/usr -- new pane (split one beside other) with cwd=/usr
```

### Respawning pane
By default, when the command running in a pane exits, the pane closes.
We can change this
```
:set-option remain-on-exit
```
and then
```
:respawn-pane        -- start new process in a pane
:respawn-pane cmd    -- run cmd in (dead) pane
:respawn-pane -k cmd -- kill current process and run cmd in pane
```

### Window sizes
```
:show -g default-size
```

```
:set-option window-size largest/smallest/latest/manual
```

Then there are keys when the window is larger than our terminal: {{{Ctrl-B}}} followed by
```
S-Up
S-Down
S-Left
S-Right
Delete -- return to tracking the cursor position
```
and commands
```
:resizew -x200 -y100        -- resize to 200x100
:resizew -A                 -- work out size from attached clients
:resizew -L20               -- adjust size left
:resizew -R20, -D20, -U20   -- same but for right, down, up
```

### Piping pane changes
```
:pipe-pane 'cat > /tmp/log1' -- pipes changes to terminal to cat
:pipe-pane                   -- stop piping
:pipe-pane -I 'cat /tmp/log1'
:pipe-pane -o 'cat > /tmp/log1' -- toggles piping
```

### Pane commands
```
:selectp -Tmytitle -- set title for pane
```
The pane title is in quotes to the lower right, the window name is next to
its number, and the session name is in square brackets to the lower left.

### Terminal window stuff
With e.g. xterm and friends, we can set the title using
```
set -g set-titles on
```
and change what the title is set to via
```
set -g set-titles-string '#{pane_title}'
```
where `'#{pane_title}'` is a format string for the title.
By default this is `'session-name:window-number:window-name - pane-name'`.


### Format strings
For things like setting the title, the format string looks like e.g.
```
'#{pane_title}'
```
and there are a few variables we can use in here. These are
```
#{pane_title}                           -- pane title
#{session_name}, #{window_name}         -- names
#{pane_id}, #{window_id}, #{session_id} -- ids
```

For example to list ids in current window
```bash
$ tmux lsp -F '#{session_id} #{window_id} #{pane_id}'
$0 @8 %8
```

### Addressing panes
Note that variable `TMUX_PANE` is set to the appropriate `pane_id`
when spawning a pane, and is unique for that pane (it is never reused by a given tmux server).

For example
```bash
tmux send -t%22 "echo hello world" Enter -- types echo hello world and presses Enter
tmux send -t%21 -l "echo hello" Enter -- Enter is sent as text
```
note that this can't send e.g "\n" -- that literally sends a backslash followed by n.

```
tmux capturep -pt%21  -- dump contents of pane %21 to stdout
... -e includes escape sequences for colours and attributes
    -C escapes nonprintable chatacters as octal sequences
    -N preserves trailing spaces at the end of lines
    -J preserves trailing spaces and joins wrapped lines
```

### More panes
Empty pane
```bash
$ tmux splitw ''
$ echo 'hello world' | tmux splitw -I  -- takes content of new pane from stdin
```

### Windows
A window can belong to more than one session.

### Escape sequences
```bash
$ printf '\033]2;newtitle\007'  -- sets terminal title
```

### Options
Options, set with `:setw`