The tmux, terminal multiplexer, like gnu screen, allows one to have multiple terminal sessions at once.
tmux
If you split a window into panes, with ctrl-B (or
with ctrl-A if you set it up that way) + "
or tmux split-window, you can see two shell sessions
at the same time.
tmux split-window
The default vertical split puts a session on top and another on the bottom and a cute horizontal line in between, drawn with pretty line drawing characters.
$ echo 'top' top $ ──────────────── $ echo 'bottom' bottom $
A SUPER cute feature is the ability to send keys from
one half to the other. Note that enter sends a "\n".
$ echo top top $ ────────────────────────────────────── $ tmux send-keys -t 0 'echo top' enter $ █
In fact, this is so cute that it could be made into a nice workflow -- type into one half and see the output in another half. The nice thing about this is that it will work even if the output is lengthy, or you are on a remote connection and want a history, or you are in some other console environment (docker, rails, python debugger session) and want to be able to keep track of what you are sending.
$ pwd /home/bduggan $ date Thu Jan 31 21:23:14 EST 2019 $ echo 123 123 ────────────────────────────────────── > pwd > date > echo 123 > █
Let's write a little program to implement this.
#!/usr/bin/env perl6
loop {
my $str = prompt '> ' or last;
run <<tmux send-keys -t 0 -l "$str">>;
run <<tmux send-keys -t 0 enter>>;
}
Let's try it out!
$ echo 'how now brown cow' how now brown cow $ echo "a b c" a b c $ seq 2 5 2 3 4 5 $ ────────────────────────────────────── > echo 'how now brown cow' > echo "a b c" > seq 2 5 > ^D $ █
tmux
can
help
with
making
a
meta-terminal
--
letting
you
send
commands
from
somewhere
else. run
in
Perl
6
is
a
handy
way
to
spawn
a
command. <<
and
>>
is
an
interpolating
word-quoting
construct
that
works
with
strings
enclosed
in
quotation
marks. prompt
returns
a
falsey
value
when
it
receives
an
end-of-file
indicator.