Linux – tmux split into 4 panes

linuxtmuxUbuntu

I am using tmux 2.1.
I have googled this and it seems I can split a window into multiple panes by using the following command:

tmux new-session \; split-window \; split-window -h \; split-window -v

(not sure why the \; is needed but it only works with it)

My issue is the the layout I want is the following:

The only way I can achieve this is by creating 3 windows horizontaly and then going back to the middle window and then splitting that window and I can only do this manually.

Is there anyway to do this via a command?
Thanks!

Best Answer

Briefly, this sequence is what you want:

tmux new-window \; split-window -p 66 \; split-window -d \; split-window -h

The flow is:

tmux new-window: create a window (ok, you wanted a new-session, that does create a window upon startup)
split-window -p 66: allocate bottom two thirds of the vertical space to a secondary pane and focus it
split-window -d: split bottom pane in half, vertically, without focusing the new pane (i.e. focus stays on second – now center – pane)
split-window -h: split center pane in half, horizontally

As for why the \; is needed, check tmux man page:

Multiple commands may be specified together as part of a command sequence. Each command should be separated by spaces and a semicolon; commands are executed sequentially from left to right and lines ending with a backslash continue on to the next line, except when escaped by another backslash. A literal semicolon may be included by escaping it with a backslash (for example, when specifying a command sequence to bind-key).

Related Solutions

Remote server, iTerm2, and tmux integration

Yes it is possible, jut make sure:

To have latest version of tmux installed remotely
Have most recent version of iterm2 installed locally

Login via ssh login@hostname -t 'tmux -CC' and voilà - this should open iTerm2 window on your local box logged into remote box.

Creating a “focus mode” for tmux? (one centered pane flanked by two blank panes?)

This is what I have under the name _tmux-margins:

#!/bin/sh

pane="${2:-$TMUX_PANE}"
[ -n "$pane" ] || exit 1
tmux has-session -t "$pane" 2>/dev/null || exit 0

tool="$0"
width="${TMUX_M_COLUMNS:-80}"
step=10
todo="${TMUX_M_COMMAND:-true}"
action="$1"
pattern=" '$tool' sleep "
pattern_left="$pattern'${pane}' left"
pattern_right="$pattern'${pane}' right"
command_left="TMUX_M_COMMAND='$todo'$pattern_left"
command_right="TMUX_M_COMMAND='$todo'$pattern_right"

tmux display-message -p '#{pane_start_command}' | grep -qF "$pattern" && exit 0

find_margins() {
    pane_left="$(tmux list-panes -F "#{pane_id} #{pane_start_command}" | grep -F "$pattern_left" | head -n 1 | cut -d ' ' -f 1)"
    pane_right="$(tmux list-panes -F "#{pane_id} #{pane_start_command}" | grep -F "$pattern_right" | head -n 1 | cut -d ' ' -f 1)"
}

find_geometry() {
    [ -n "$pane_left" ] && width_left="$(tmux display-message -p -t "$pane_left" '#{pane_width}')" || width_left=0
    [ -n "$pane_right" ] && width_right="$(tmux display-message -p -t "$pane_right" '#{pane_width}')" || width_right=0

    border=0
    [ "$width_left" -gt 0 ] && border=$((border+1))
    [ "$width_right" -gt 0 ] && border=$((border+1))

        width_center="$(tmux display-message -t "$pane" -p '#{pane_width}')"
    width_all="$((width_center+width_left+width_right+border))"

    [ "$((width+5))" -ge "$width_all" ] && width="$width_all"
}

destroy() {
    [ -n "$pane_left" ] && [ "$pane_left" != "$TMUX_PANE" ] && tmux kill-pane -t "$pane_left"
    [ -n "$pane_right" ] && [ "$pane_right" != "$TMUX_PANE" ] && tmux kill-pane -t "$pane_right"
    [ "$pane_left" = "$TMUX_PANE" ] || [ "$pane_right" = "$TMUX_PANE" ] && tmux kill-pane -t "$TMUX_PANE"
    true
}


create() {
    width_left=$(( (width_all-width-2)/2 ))
    [ "$width_left" -gt 2 ] || width_left=2
    if [ -n "$pane_left" ]; then
        tmux resize-pane -t "$pane_left" -x "$width_left"
    else
        tmux split-window -hdbl "$width_left" -t "$pane" "$command_left"
    fi

        width_right=$(( width_all-width-width_left-2 ))
        [ "$width_right" -gt 2 ] || width_right=2
    if [ -n "$pane_right" ]; then
        tmux resize-pane -t "$pane_right" -x "$width_right"
    else
        tmux split-window -hdl "$width_right" -t "$pane" "$command_right"
    fi
}

equalize() {
        width="$width_center"
    [ "$width" -lt "$width_all" ] && create
}

verify() {
    tmux has-session -t "$pane" 2>/dev/null || destroy
}

resize() {
    width="$((width_center${1}))"
    if [ "$((width+5))" -ge "$width_all" ]; then
        destroy
    else
        create
    fi
}

main() {
    find_margins
    find_geometry
    case "$action" in
        sleep )
            trap destroy INT
            trap 'verify; kill "$!" 2>/dev/null; $todo &' WINCH
            while true; do
                $todo &
                while sleep 1; do verify; done
            done
        ;;
        ""|c* )
            create
        ;;
        d* )
            destroy
        ;;
        e* )
            equalize
        ;;
        + )
            resize "+$step"
        ;;
        - )
            resize "-step"
        ;;
        +*|-* )
            resize "$action"
        ;;
    esac
}

main

There are some fragments and solutions I'm not proud of. Still it works.

Use it like this (provided it's in a directory in your $PATH):

To create margins:
- _tmux-margins c
- or _tmux-margins create
- or _tmux-margins cwhatever (in fact anything that starts with c)
- or _tmux-margins (create is the default action).
To destroy margins:
- _tmux-margins d (in fact anything that starts with d: del, delete, destroy, dwhatever).
To equalize width of margins:
- _tmux-margins e (in fact anything that starts with e).
To enlarge the center pane (shrink margins):
- _tmux-margins +
- or _tmux-margins +N (add N columns to the center pane, if possible).
To shrink the center pane (enlarge margins):
- _tmux-margins -
- or _tmux-margins -N (subtract N columns from the center pane, if possible).

The second argument (not used in the above examples) specifies the pane. This way you can invoke the tool from another pane or from the outside of tmux. Examples:

_tmux-margins c .1
_tmux-margins - %5

There are two useful variables:

TMUX_M_COLUMNS – desired width of the center pane when margins are created (80 if unset).
TMUX_M_COMMAND – command to run in margin panes (true if unset). If a margin is resized, the command will be restarted. The main reason I implemented this:
```
TMUX_M_COMMAND='cmatrix -u 20' _tmux-margins create
```

I have this in my ~/.tmux.conf:

bind-key -T root C-Up    run-shell -b 'TMUX_PANE="#{pane_id}" _tmux-margins d "#{pane_id}"'
bind-key -T root C-Down  run-shell -b 'TMUX_PANE="#{pane_id}" _tmux-margins c "#{pane_id}"'
bind-key -T root C-Left  run-shell -b 'TMUX_PANE="#{pane_id}" _tmux-margins - "#{pane_id}"'
bind-key -T root C-Right run-shell -b 'TMUX_PANE="#{pane_id}" _tmux-margins + "#{pane_id}"'

These lines make Ctrl+↑, Ctrl+↓, Ctrl+← and Ctrl+→ invoke _tmux-margins d, … c, … - and … + respectively, targeted at the current pane.

Notes:

These key combinations work for me locally on Linux and via ssh from Linux to Linux. They don't work for me when I'm on Windows using PuTTY to connect to Linux. I have not attempted to fix this issue. Maybe it's possible to configure PuTTY so it works, I don't know. In any case you can choose other combinations, possibly with the prefix key (bind-key -T prefix …).
Go ahead and map _tmux-margins e as well, if you find it useful.
The script invoked with a keystroke has no access to the environment of the shell in the current pane (compare this answer). This means in order to use TMUX_M_COLUMNS or TMUX_M_COMMAND with keystrokes you need to set them for the tmux server itself:
- for the very first tmux (the one that starts the server):
```
TMUX_M_COMMAND='cmatrix -b' tmux
```
- or in your ~/.tmux.conf:
```
set-environment -g TMUX_M_COMMAND 'cmatrix -b'
```
  (note -g (global environment) is a must because tmux.conf is parsed before any session starts);
- or later (when tmux server is running) like this:
```
tmux set-environment TMUX_M_COMMAND 'cmatrix -b'
```
  (with or without -g; note if not inside tmux, then you need -g or -t);
- or from the inside of tmux:
  
  prefix:set-environment TMUX_M_COMMAND 'cmatrix -b'Enter
  
  (again, with or without -g).

General notes:

Margins are just panes. If you split a margin or swap it with another pane or break it out of the window, so it doesn't look like a proper margin, then it's your problem. Or if you split the center pane etc.
On the other hand you can resize a margin like any other pane (possibly with a mouse); then _tmux-margins e is useful.
My script tries not to create margins for margins.
Destroying one margin destroys the other. You can select a margin and hit Ctrl+c instead of invoking _tmux-margins d.
Destroying a pane destroys its margins (if they exist).

Best Answer

Related Solutions

Remote server, iTerm2, and tmux integration

Creating a “focus mode” for tmux? (one centered pane flanked by two blank panes?)

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