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Automatic restarts for a Left 4 Dead 2 server

A Left 4 Dead 2 session is a campaign, and restarting ends whatever campaign is running. That makes scheduling one harder to justify here than almost anywhere else.

When should it restart?

Put {{minutes}} wherever the number of minutes left should appear.

What happens, in order

  1. Job startsWarnsay Server restarting in 15 min
  2. 10 min beforeWarnsay Server restarting in 10 min
  3. 5 min beforeWarnsay Server restarting in 5 min
  4. 1 min beforeWarnsay Server restarting in 1 min
  5. Restart timeStopquit

Nothing to save. A restart drops any campaign in progress, so favour a long interval over a short one.

The crontab line

Moved 15 minutes ahead of the time you picked, so the restart happens at that time instead of 15 minutes later.

45 3 * * *  /opt/restart-l4d2.sh

The script it runs

Save it as /opt/restart-l4d2.sh and mark it executable. It expects rcon-cli on the path and takes the password from an environment variable instead of storing it in the file.

#!/usr/bin/env bash
set -euo pipefail

# Scheduled restart for Left 4 Dead 2.
# Generated by spawnbench.com/restart-scheduler

# The password stays out of this file. Put it in the environment, or in a
# file only root can read, and export it before this script runs.
RCON_HOST="${RCON_HOST:-127.0.0.1}"
RCON_PORT="${RCON_PORT:-27015}"
: "${RCON_PASSWORD:?set RCON_PASSWORD before running}"

send() {
  rcon-cli --host "$RCON_HOST" --port "$RCON_PORT" --password "$RCON_PASSWORD" "$1"
}

# 15 minute warning
send 'say Server restarting in 15 min'

sleep 300
# 10 minute warning
send 'say Server restarting in 10 min'

sleep 300
# 5 minute warning
send 'say Server restarting in 5 min'

sleep 240
# 1 minute warning
send 'say Server restarting in 1 min'

sleep 70
# Shut down cleanly
send 'quit'

# Give the process time to finish writing before anything restarts it.
sleep 30
systemctl start l4d2 2>/dev/null || true

Heads up: cron follows the server clock, not your local time. Check with timedatectl first. A container set to UTC and an admin living in Europe differ by two hours in summer and by one in winter, so 04:00 may not be the 04:00 you had in mind.

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What is different about Left 4 Dead 2

Go for a long gap — weekly, not daily — at an hour when no group is halfway through a campaign. With nothing to save, the only price of a restart is the session it cuts short, and that price depends entirely on when it happens.

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Rather not run the server yourself?

These tools are free and funded by the two hosting services we run. If you want a server that is already set up, here they are.

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