How to Keep a Bot Running After SSH Disconnects

Command of the Day

nohup node index.js > output.log 2>&1 &

What it does: Executes a command immune to hangups (SIGHUP), redirecting standard output and errors to a log file in the background.

When you log into a Linux VPS over SSH and start a process (like node bot.js or python3 bot.py), that process is attached to your active SSH terminal session. As soon as you close your terminal or disconnect from SSH, the operating system kernel sends a SIGHUP (Signal Hangup) to all child processes, immediately terminating your bot.

In this guide, we cover four effective methods to keep your bots and scripts running continuously on your RivinCloud VPS even after logging out.

1. The 4 Methods Overview

               ┌─────────────────────────────────────────────────────────┐
               │    How do you want to detach your process from SSH?     │
               └────────────────────────────┬────────────────────────────┘
                                            │
         ┌──────────────────┬───────────────┴───────────────┬──────────────────┐
         ▼                  ▼                               ▼                  ▼
    Method 1: nohup     Method 2: Screen               Method 3: Tmux     Method 4: PM2 (Best)
  (Simple background) (Multiplexer session)        (Advanced session) (Supervisor + Auto-restart)

2. Method 1: Using `nohup` (Simple Backgrounding)

The nohup (No Hangup) command instructs the Linux kernel to ignore SIGHUP signals.

nohup node index.js > bot.log 2>&1 &

nohup: Ignores disconnect signals.
> bot.log: Redirects standard output to bot.log.
2>&1: Redirects error output to the same log file.
&: Runs the process in the background.

To check if it's running:

ps aux | grep node

To stop it:

kill <PID>

3. Method 2: Using GNU Screen

screen creates a virtual terminal session that remains active on the server independently of your SSH login.

Start a named screen session:
```
screen -S mybot
```
Start your bot normally:
```
python3 bot.py
```
Detach from session: Press Ctrl + A, then press D. You can now safely close your SSH terminal!
Re-attach to the session later:
```
screen -r mybot
```

4. Method 3: Using PM2 (Production Standard)

For production Node.js or Python bots, PM2 is the superior solution because it not only detaches the process, but also handles auto-restarts on crash and server reboots:

# Install PM2
sudo npm install -g pm2

# Start process
pm2 start index.js --name "discord-bot"

# Save state for VPS reboots
pm2 save

Command of the Day: `nohup`

The nohup command allows commands to run in the background immune to terminal hangups.

Syntax

nohup [command] [arguments] [redirection] &

Practical Example

nohup python3 -u script.py > script.log 2>&1 &

Explanation

-u: Tells Python to run in unbuffered mode so log lines are written to script.log immediately without buffering delay.
The trailing & releases your prompt so you can continue using the terminal.

Common Mistakes

Forgetting the trailing & with nohup: Without &, the command occupies your active terminal prompt.
Forgetting to save PM2 list: Running pm2 start without pm2 save means the process won't restore automatically if your VPS reboots.

Troubleshooting

nohup: ignoring input and appending output to 'nohup.out': You didn't specify a log file destination, so nohup created a default nohup.out file in your current directory.

Best Practices

Use screen or tmux for interactive command interfaces.
Use PM2 or Systemd for production 24/7 background daemons.

Frequently Asked Questions

How do I kill a process started with `nohup`?

Find its Process ID using pgrep -f "script.py", then send a termination signal: kill <PID>.

Conclusion

Keeping bots running after SSH disconnects is fundamental to cloud server administration. Leverage nohup, screen, or PM2 on your RivinCloud VPS to ensure continuous bot operation!