FIXING TMUX NOT RUNNING SHELL COMMANDS
The joys of tmux
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I've been moving more of my shell life into `tmux'. I find it to be a
very pleasant bit of software. I've picked it up with relative ease
thanks to its thoroughly document man-page, sensical key-bindings, and
smooth integration into my existing "all-text" lifestyle.
My favorite thing about `tmux' is how it keeps my sessions alive even
when I close its enclosing terminal. My sometimes slippery fingies
might accidentally close a window (oops!). I've gained confidence from
`tmux' knowing that I can reconnect a client to the server's sessions
anytime. There's also a workflow boon from this feature: I can connect
multiple clients if I want to have `tmux' open in multiple `i3'
workspaces.
Multiplexing more
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I want to spend more time in `tmux'. I've become so familiar and
frequent with it that I'll sometimes forget a `urxvt' window isn't
inside a `tmux' client. This means that I can't take advantage of
`tmux''s copy mode, among other things.
I use `plumber' to plumb links inside a terminal window. Basically,
`urxvt-matcher' matches for certain URIs and then sends those to a
Python script, `plumb', which moves the URL along to the relevant
opener (YouTube, Gopher, Firefox, etc.) A lot of links I visit open
`lynx' in a new terminal window. What I'd like to do instead is have
those links open `lynx' on an existing `tmux' server. The first step
towards this improvement is learning how to start a new shell command
inside an existing `tmux' server.
Fixing what's broken
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`tmux' documentation states a user can invoke `new-session' to run a
given shell command on an existing `tmux' server. In whole, the
command looks something like this:
,----
| tmux new-session "lynx gopher://roygbyte.com"
`----
For me, this didn't work out of the box. The behavior I observed was
that the session immediately exited. Weird! I thought maybe I was
missing a switch for the command. I tried different switches. I ran
the `new-session' command inside and outside `tmux'. I tried different
programs: `top' and `emacs -nw' also exited immediately. Oddly,
running `ed' worked fine (that's why it's the standard). This got me
thinking my virtual terminal could be a problem.
A suggested commands are suppose to exit. In other words, this is the
intended behavior. It also suggested a work around (which did work!)
of `tmux send-keys -t session-id "lynx gopher://roygbyte.com" ENTER'.
I didn't accept the work around as a solution for me. I wanted to know
what was wrong with my setup. There was mention of debugging using the
`remain-on-exit' option. So I turned this on (`set -g remain-on-exit
on') and invoked my initial `new-session' command again. Lo! The
session read: "Terminal initialisation failed - unknown terminal
type?".
So the issue *is* with my terminal, which `$TERM' evaluates as
`rxvt-unicode-256'. Looking through gave me ideas about what to do
next, particularily: tmux has a `default-terminal' option. So I set
that to be the same as `$TERM', `rxvt-unicode-256color' and tada,
t'works. The `new-session' command completes and `lynx' has
successfully opened the URL I supplied as an argument. Yay!
In concluson
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This issue was a standard-issue "gotcha!". It's also a wake up call
for me to better understand what a terminal even is. I spend so much
of my life inside these things yet I don't understand their
principals. Like: why do some people use `st' over `urxvt' or `xterm'?
And: what's a virtual terminal, anyways? I can't answer these
questions but I hope to find answers soon.
Anyways, this was a fun little thing to dig into. I gained a few
anciliary outcomes: this phlog post and a new `tmux' config file. I
started it with some help from . Not much in it yet, but I'm sure it
will grow over time:
,----
| unbind C-Space
| set -g prefix C-Space
| bind C-Space send-prefix
| set -g mouse on
| set -g renumber-windows on
| set -g remain-on-exit on
| set -g default-terminal rxvt-unicode-256color
`----
My thanks to eidolon, too, who helped debug. They also mentioned a
nice plumber hax: `bind-key -T copy-mode-vi p send-keys -X copy-pipe
"plumb -"'. Make a copy in copymode and press P to send "pay the
plumber". I haven't tried this yet, but I someday will.