Attaching to tmux

Select an explicit socket, capture the existing server, and find the work session. The program prints its name and leaves the server running. A missing server or session ends the program with an error.

This controls tmux from Julia. To open a session in your terminal, use tmux attach-session; the shared guide covers interactive attachment and detaching.

Connect to an existing server¶

Save the complete program as connect.jl. The environment variable LIBTMUX_SOCKET_PATH selects the existing server. The launcher below sets it to a private socket for trying the example.

using LibTmux

function main()
    server = Server(; socket_path=ENV["LIBTMUX_SOCKET_PATH"])
    captured = snapshot(server)
    session = onlymatch(SessionWhere(; name="work"), sessions(captured))
    println(session.name)
end

main()

Constructing SServer performs no I/O. fsnapshot explicitly reads tmux and returns captured state. The local SSessionWhere query filters that state; fonlymatch requires exactly one result. Reading or filtering captured values does not refresh them.

The server value borrows the daemon. It does not own a process to close, and the program does not destroy the caller’s sessions.

Setup and run¶

Use an empty directory on Linux with Julia 1.13, Git, POSIX shell, and tmux installed. Run the following commands in a POSIX shell. Fetch the library revision used by this program:

$ git init -q source
$ git -C source fetch -q --depth=1 \
  https://github.com/libtmux/libtmux-julia.git \
  6f62bd72cb8d99f3759ca5e2cc3591165a03c768
$ git -C source checkout -q --detach FETCH_HEAD

Save the launcher as run.sh. It starts an isolated tmux server, runs the program, checks that the session still exists, then stops only that server. Cleanup runs after failures too. A failed shutdown keeps its socket directory and prints its location for inspection.

#!/bin/sh
set -eu

binary=$(command -v tmux)
directory=$(mktemp -d "${TMPDIR:-/tmp}/libtmux-julia-attach.XXXXXX")
socket="$directory/tmux.sock"

cleanup() {
    status=$?
    trap - 0 HUP INT TERM
    if [ -S "$socket" ] && ! "$binary" -S "$socket" kill-server; then
        printf 'Cannot stop tmux; kept %s\n' "$directory" >&2
        exit 1
    fi
    rm -rf "$directory" || exit 1
    exit "$status"
}
trap cleanup 0
trap 'exit 1' HUP INT TERM

unset TMUX TMUX_PANE
export LIBTMUX_SOCKET_PATH="$socket" TMUX_BIN="$binary"
"$binary" -S "$socket" -f /dev/null new-session -d -s work /bin/cat
"$@"
"$binary" -S "$socket" has-session -t '=work'

$ sh run.sh julia --startup-file=no --project=source connect.jl

The program prints work. To use your own existing server, set LIBTMUX_SOCKET_PATH to its socket and run the program without the launcher. The launcher owns only the demonstration server.

Find or create a session¶

Reading a session does not reserve its name. If your application creates a session after an unsuccessful lookup, another client may create the same name between those operations. Handle the creation error as well as the lookup.

Captured queries explains local selection. Capture from an owned server is a complete program that creates and stops its own daemon.

The library source revision records the implementation used by this example.