Run multiple commands from the command line, with shared STDOUT

doall

#!/usr/bin/env bash

set -euo pipefail

syntax() {
    cat <<EOF
Evaluate multiple commands passed as arguments.

Commands are separated with `--` (double dash). If it doesn't precede `--`, the final
command will be run in the foreground, with stdin connected to the terminal. All other
commands are sent to the background.

Example:

doall run-daemon -p 8080 -- bash -c "sleep 2 && nc localhost 8080"

EOF
}


invoke() {
    "$@" &
    pids+=($!)
}

invoke_all() {
    pids=()
    xs=()

    for arg in "$@"
    do
        case "$arg" in
            --)
                invoke "${xs[@]}"
                xs=()
                ;;
            *)
                xs+=("$arg")
                ;;
        esac
    done

    if [[ ${#xs[@]} -ne 0 ]]; then
        "${xs[@]}"
    else
        wait "${pids[@]}"
    fi
}

trap "exit" INT TERM
trap "kill 0" EXIT

invoke_all "$@"