Capture a pane

Create a private tmux server, capture the screen of a pane running /bin/cat, and keep the captured snapshot after the server has stopped.

Setup¶

Julia 1.13.0, Git, POSIX shell and tmux on Linux. Start in an empty directory. The following commands run 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

Program¶

Save this complete program as owned_capture.jl.

using LibTmux

function main()
    endpoint = Ref{Server}()
    result = with_server(; tmux=get(ENV, "LIBTMUX_TEST_TMUX", "tmux")) do server
        endpoint[] = server
        new_session(server; name="example", command=["/bin/cat"])
        snap = snapshot(server)
        pane = only(panes(snap))
        screen = capture_pane(server, pane.ref)
        @assert isempty(strip(screen))
        @assert only(sessions(snap)).name == "example"
        println("Captured ", string(pane.id), ": ", ncodeunits(screen), " screen bytes")
        (; snap, screen)
    end
    @assert !ispath(dirname(endpoint[].socket_path))
    @assert length(panes(result.snap)) == 1
    result
end

main()

fwith_server owns the daemon and its temporary socket directory. The program asserts that the directory is gone after the block returns and that the captured snapshot still contains its pane.

The pane has no text. Its captured screen contains blank lines, so the byte count depends on its height; strip(screen) is empty.

Run¶

$ unset TMUX TMUX_PANE
$ export ENV=/dev/null BASH_ENV=/dev/null SHELL=/bin/sh
$ julia --startup-file=no --project=source owned_capture.jl

Expected output:

Captured %0: 24 screen bytes

Related APIs¶

• fwith_server
• fsnapshot
• fcapture_pane

Source and verification¶

The complete program comes from examples/owned_capture.jl. The verification runner executes these displayed files and setup commands unchanged, checks the output, and checks that the program stopped its private tmux server. Each example runs independently.