Fish function to run multiple commands in parallel

in-parallel.fish

argparse "n/name=" "c/commands=+" -- $argv
or return

set n (count $_flag_commands)

tmux has-session -t "$_flag_name"
if test "$status" -eq "0"
    echo "tmux session already exists for $_flag_name, maybe still running?"
    echo "Try `tmux new -As $_flag_name` to attach to it."
    return 1
end

tmux new-session -ds "$_flag_name" -x $COLUMNS -y $LINES

# Split the first pane into many
for i in (seq 2 $n)
    tmux split-window -t "$_flag_name"
end

# Even out tiles horizontally and vertically
tmux select-layout -t "$_flag_name":0.0 tiled

for i in (seq $n)
    set pane (math $i-1)
    tmux send-keys -t "$_flag_name":0."$pane" "fish -c \"$_flag_commands[$i] && exit\" && exit" Enter
end

tmux attach-session -t "$_flag_name"