Hopping

A hop is a terminal on another machine. Everything in this chapter assumes at least two linked machines; the examples sit at benzene and hop to toluene.

The mesh view: `jaunt`

jaunt with no arguments, on a terminal, opens the live mesh view: this machine on the left, a line to every other member, and an event log underneath. The style of a line is its path: solid green for direct, dotted amber through the relay, dim for offline. Each line carries the latency of the last minute as a small sparkline.

Key	Does
arrows, or `j` / `k`	choose a machine
Enter	hop to it
`l`	link a new machine
`?`	help
`q`	quit

When the output is not a terminal (piped into another command), jaunt behaves like jaunt ls.

Hop: `jaunt toluene`

jaunt toluene

This opens the tmux session called jaunt on toluene, creating it the first time. A one-line banner says how you got there, for example benzene ━━▸ toluene · direct · 0.8 ms, and you are in.

Same session every time. Leave and come back, and you are on the same screen with the same programs running. The session lives in tmux on toluene; it outlives the connection, the client and the daemon.
Other sessions. jaunt toluene:work opens or creates a session called work, separate from the default one.
Prefixes. Any unambiguous start of a name works: jaunt tol is jaunt toluene. If a prefix matches two machines, jaunt lists them and asks you to type more of the name.
jaunt hop toluene is the same command spelled out.

A hop needs a terminal. To run something from a script, use jaunt run.

The other commands

Command	Does
`jaunt ls`	every machine: direct, relayed or offline, latency, host state, sessions
`jaunt ls --json`	the same as JSON. Piped, plain `jaunt ls` prints tab-separated columns: name, state, latency, host, sessions, id, with this machine first as `self`
`jaunt run toluene -- uname -a`	run one command on toluene; its output and exit status come back
`jaunt cp notes.txt toluene:docs/`	copy a file or a directory. Either side can be `machine:path`; remote paths are relative to the home directory there
`jaunt fwd toluene 8080`	make toluene’s `127.0.0.1:8080` available here at `127.0.0.1:8080`, until Ctrl-C
`jaunt fwd toluene 8080:9090`	the same, but here at port 9090
`jaunt pipe toluene [port]`	connect stdin and stdout to a port on toluene’s loopback (default 22)

fwd reaches only toluene’s loopback. The local end listens on 127.0.0.1, so every user of this machine can use the port while it runs, as with ssh -L. Held forwards, reverse forwards, a SOCKS proxy and jaunt open: Ports, tabs and the clipboard.

jaunt pipe carries OpenSSH. Where sshd listens on loopback, this in ~/.ssh/config sends ssh, scp, rsync and git through jaunt, with SSH’s key check as a second layer:

Host benzene toluene xylene phenol
    ProxyCommand jaunt pipe %h

The Host names must be jaunt machine names.

Onward hops

Every machine is a full member, so you can hop from where you are. Inside a hop on toluene, jaunt xylene goes on from toluene to xylene. The shell in a hop has two variables set:

Variable	Holds
`JAUNT_FROM`	the machine you came from
`JAUNT_MACHINE`	the machine you are on

Getting out and back

The escape keys are read by jaunt itself, before any tmux sees them, so they always work. They start with Enter, as in OpenSSH.

You want to	Do	Session on the other machine
leave a hop	Enter, then `~`, then `.`	kept
see the escape keys	Enter, then `~`, then `?`
type a literal `~` at the start of a line	Enter, then `~`, then `~`
detach from the remote tmux (not nested)	Ctrl-b, then `d`	kept
go back	`jaunt toluene` (same session, same screen)
use a second session there	`jaunt toluene:work`	separate session
end the session for good	type `exit` in the remote shell	ended
quit the mesh view	`q`
stop linking	Ctrl-c (or `n` at the question)

On the way out a banner says where you are again: ◂━━ back on benzene · session kept on toluene.

When the link drops

A change of network (Wi-Fi to a phone hotspot) is absorbed by QUIC: the connection moves to the new path, and typing resumes within about half a second. Nothing on your screen changes except the path in jaunt ls.

When the connection is really lost (the lid closed, the Wi-Fi gone), jaunt keeps your terminal and shows one status line at the bottom:

toluene ╌ link lost · retrying in 4s · ~. to give up

It tries again after 1 second, then 2, 4, 8, and every 10 seconds after that, and re-attaches by itself when toluene is back; tmux then repaints the screen as it was. ~. gives up at any time, and the session stays on toluene.

There is a second, quieter line. If you type and nothing at all (no output, no acknowledgement, no keep-alive) has come back from toluene for 3 seconds, the bottom row says:

toluene ╌ no answer for 5s · waiting for the link · ~. to give up

It disappears as soon as output arrives. A program that is simply quiet on a live link, such as a password prompt, does not trigger it.

Without tmux on the far machine, a hop is a plain login shell, and it ends when the link drops. jaunt check on that machine warns about it.

Using jaunt from tmux

A hop from inside tmux works without setup. The snippet below adds a popup picker that opens each machine in its own window, and a key that hands your keys to the tmux on the other machine.

The tmux snippet

jaunt tmux-setup

then add this one line to your ~/.tmux.conf and reload tmux:

source-file ~/.config/jaunt/jaunt.tmux

Key	Does
prefix `J` (default prefix is Ctrl-b, so Ctrl-b then Shift-j)	the mesh view in a popup. Enter opens the hop in a new window named after the machine, so each machine gets its own window
`F12`	hand your keys to the tmux on the other machine. The status bar shows `F12 keys to remote` while this is on. Press `F12` again to get them back

Nothing else is bound; your prefix and Ctrl-h/j/k/l are untouched.

Nested tmux

If you hop from inside tmux, there are now two tmux programs on your screen: yours (the outer one) and the one on the other machine (inside the window). Your prefix key (Ctrl-b) always goes to the outer one first.

To talk to the remote tmux: press F12 once (with the snippet), then use Ctrl-b as usual; press F12 again to come back. Without the snippet: press the prefix twice (Ctrl-b Ctrl-b) then the key, as usual in tmux.
To detach from the remote tmux: F12, then Ctrl-b d. You are back in your outer tmux, and the remote session stays.
When in doubt, Enter ~ . always works: it is read by jaunt itself, not by either tmux.

Keyboard shortcuts

jaunt manual