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Tested on OpenBSD 6.3

Manage terminals with tmux(1)

tmux(1) is a terminal multiplexor.


To create and attach to a new session run:

$ tmux

You've got a green status bar at the bottom of the window. That means now you're attached to a tmux session with name 0 (in the left bottom corner [0]) in the first and only window open number 0 and name ksh (0:ksh*).

To detach from tmux session press C-b d (Ctrl-b and then d) or you can just kill your terminal window. C-b is the default PREFIX key in tmux(1). The session stays intact.

To attach to existing session instead of tmux run:

$ tmux new -A -s 0

tmux(1) tries to attach (-A) to the existing session (-s 0) and if fails then it creates a new session.


To create a new window press PREFIX c. You've got another window created and selected (1:ksh*).

To select window 0 press PREFIX 0, to select 1 press PREFIX 1.

To close a window close program its running (to exit shell press C-d) or you can kill the window with PREFIX d. By default name of a window changes to its active program (for example, ksh).

To rename a window press PREFIX , then edit its name and hit Enter. Once a window is renamed its name will persist for the session.


With tmux(1) you can split a window into panes. PREFIX " to split horizontally and `PREFIX %' to split the window vertically.

To select another pane use PREFIX arrow, where arrow is up, down, left, or right.

To resize panes use PREFIX c-arrow.

Press PREFIX just once, then press arrow as many times as you need to select (or c-arrow to resize). But key press intervals should be under 500 ms (see repeat-time option), otherwise you need to press PREFIX again.

Action Keys
Open a window PREFIX c
Select windows 0 to 9 PREFIX 0 ... PREFIX 9
Rename the window PREFIX ,
Kill the window PREFIX x
Veritical split PREFIX %
Horizontal PREFIX "
Select a pane PREFIX up
PREFIX right
Resize the pane PREFIX c-up
PREFIX c-down
PREFIX c-left
PREFIX c-right


Keep one session at a time and use one window per task. Inside each window open multiple panes.

To start tmux(1) use this shell function:

start_tmux() {
  if ! tmux new-session \
    -As 0 -n "$1" "cd $2 && $3" 2>/dev/null;then
    if tmux select-window -t "$1" 2>/dev/null;then
      if tmux list-windows|
        grep ": ${1}\\*">/dev/null;then
        cd "$2"||return
      if tmux show-window-option \
        automatic-rename|grep off>/dev/null;then
        tmux new-window -n "$1" -c "$2" sh -c "$3"
        tmux rename-window "$1" && cd "$2" && sh -c "$3"

start_tmux() requires three arguments: a window name, its working directory, and initial command.

Here is a shortcut:

www() { start_tmux 'www' "$HOME/src/www" 'vi'; }

Run www from anywhere:

$ www

It tries to create a new session (0), if the session already exists and the window (www) is selected, it changes to the working directory ($HOME/src/www), otherwise it creates that window (www) and runs the initial command (vi,

See also

.tmux.conf, .profile, status, tmux wiki.