{
    ...
    "scripts": {
        "app1:dev": "nuxt --config-file src/app1/nuxt.config.js -p=3000",
        "app2:dev": "nuxt --config-file src/app2/nuxt.config.js -p=4000",
        "dev": "concurrently "npm run app1:dev" "npm run app2:dev"",
    },
    "dependencies": {
        ...
    },
    "devDependencies": {
        "concurrently": "^3.6.0",
        "cross-env": "^5.2.0"
    }
}

/home/ubuntu/.pm2/pm2.log :
PM2        | [2018-08-16T10:05:55.046Z] PM2 log: ===============================================================================
                                                                ...
PM2        | [2018-08-16T10:07:32.825Z] PM2 log: App [app1] with id [0] and pid [11135], exited with code [1] via signal [SIGINT]
PM2        | [2018-08-16T10:07:32.827Z] PM2 log: Starting execution sequence in -fork mode- for app name:app1 id:0
PM2        | [2018-08-16T10:07:32.828Z] PM2 log: App name:app1 id:0 online
PM2        | [2018-08-16T10:07:33.105Z] PM2 log: App [app1] with id [0] and pid [11145], exited with code [1] via signal [SIGINT]
PM2        | [2018-08-16T10:07:33.106Z] PM2 log: Starting execution sequence in -fork mode- for app name:app1 id:0
PM2        | [2018-08-16T10:07:33.108Z] PM2 log: App name:app1 id:0 online
PM2        | [2018-08-16T10:07:33.383Z] PM2 log: App [app1] with id [0] and pid [11155], exited with code [1] via signal [SIGINT]
PM2        | [2018-08-16T10:07:33.383Z] PM2 log: Script /usr/local/bin/npm had too many unstable restarts (16). Stopped. "errored"

/home/ubuntu/.pm2/logs/app1-error.log :
/home/ubuntu/.pm2/logs/app1-out.log :
                            ...
0|app1   | Specify configs in the ini-formatted file:
0|app1   |     /home/ubuntu/.npmrc
0|app1   | or on the command line via: npm <command> --key value
0|app1   | Config info can be viewed via: npm help config
0|app1   |
0|app1   | npm@5.6.0 /usr/local/lib/node_modules/npm
0|app1   |
0|app1   | Usage: npm <command>
0|app1   |
0|app1   | where <command> is one of:
0|app1   |     access, adduser, bin, bugs, c, cache, completion, config,
0|app1   |     ddp, dedupe, deprecate, dist-tag, docs, doctor, edit,
0|app1   |     explore, get, help, help-search, i, init, install,
0|app1   |     install-test, it, link, list, ln, login, logout, ls,
0|app1   |     outdated, owner, pack, ping, prefix, profile, prune,
0|app1   |     publish, rb, rebuild, repo, restart, root, run, run-script,
0|app1   |     s, se, search, set, shrinkwrap, star, stars, start, stop, t,
0|app1   |     team, test, token, tst, un, uninstall, unpublish, unstar,
0|app1   |     up, update, v, version, view, whoami
0|app1   |
0|app1   | npm <command> -h     quick help on <command>
0|app1   | npm -l           display full usage info
0|app1   | npm help <term>  search for help on <term>
0|app1   | npm help npm     involved overview
0|app1   |
                          ...