Tmux run program in parallel

tile

#!/bin/bash

# requires:
# set-option -ga update-environment ' TILE_NUM'

SESSION="$(date +%Y-%m-%d-%H-%M-%S)"

TILES="$1"
re='^[0-9]+$'
if [[ ! $TILES =~ $re ]]; then
    echo "usage: $0 <num> <cmd>"
    echo '    <num>      number of tiles'
    echo '    <cmd>      command to execute'
    echo
    echo 'Environment variable TILE_NUM will be set per call'
    exit 1
fi

shift
CMD="$@"

TILE_NUM='0' TILE_COUNT="$TILES" tmux new-session -s "$SESSION" -d "$CMD"

for i in $(seq 1 $(($TILES - 1))); do
    tmux set-environment -t "$SESSION" 'TILE_NUM' "$i"
    tmux split-window  -t "$SESSION" "$CMD"
    tmux select-layout -t "$SESSION" tile
done

tmux attach-session -t "$SESSION"