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LINUX Telegram TEMP alert

A simple CPU temperature alerting system for Proxmox / Linux, with notifications over Telegram. The script reads the package temperature via lm-sensors and, when a threshold is exceeded, sends a message to a Telegram bot. A second notification is sent when the temperature drops back below the threshold.

Periodic execution is handled by a systemd timer, not by an internal loop: the script is invoked at regular intervals, performs a single check, and exits.

Repository contents

File Description
alertemp.sh Main script: reads the temperature and sends alerts
tempcheck.service systemd unit (one-shot) that runs the script
tempcheck.timer systemd timer that triggers the service periodically
install.sh Automated installer (dependencies, files, units, activation)

Requirements

  • lm-sensors (the sensors command)
  • curl
  • systemd
  • A Telegram bot and its chat ID (see below)

On Debian/Ubuntu/Proxmox: apt install lm-sensors curl On Fedora: dnf install lm_sensors curl

If sensors does not show the Package id 0: line, run sensors-detect first (answering YES to the defaults), or adjust the SENSOR_LABEL variable in the script to match your output.

Creating the Telegram bot

  1. In Telegram open @BotFather, create a bot with /newbot and note the token.
  2. Start a chat with your bot (send it any message).
  3. Get your chat ID: open https://api.telegram.org/bot<TOKEN>/getUpdates and read the chat.id field.

Automated installation (recommended)

From the repository folder:

sudo ./install.sh

To run it as a user other than root:

sudo RUN_USER=monitor ./install.sh

The installer:

  • checks and installs the dependencies (sensors, curl);
  • copies alertemp.sh (to /root/ for root, to /usr/local/bin/ for other users);
  • creates the credentials template /etc/alertemp.env (permissions 600);
  • installs and configures the units, aligning user and path;
  • enables and starts the timer.

After installation, edit the credentials:

sudo nano /etc/alertemp.env

Manual installation

# 1. Script
sudo cp alertemp.sh /root/ && sudo chmod +x /root/alertemp.sh

# 2. Credentials (kept outside the script, do NOT commit them)
sudo tee /etc/alertemp.env > /dev/null << 'ENVEOF'
TELEGRAM_BOT_TOKEN="123456:ABC..."
TELEGRAM_CHAT_ID="123456789"
ENVEOF
sudo chmod 600 /etc/alertemp.env

# 3. systemd units
sudo cp tempcheck.service tempcheck.timer /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now tempcheck.timer

Configuration

Variables are set in /etc/alertemp.env (or as Environment= in the service):

Variable Default Description
TELEGRAM_BOT_TOKEN — Bot token (required)
TELEGRAM_CHAT_ID — Destination chat ID (required)
THRESHOLD 80 Alert threshold in degrees C
SENSOR_LABEL Package id 0: Line of sensors to read
ALERT_FILE /tmp/alertemp_<host>_sent Anti-spam state file

The check interval is set in tempcheck.timer (default: every 30 s):

[Timer]
OnBootSec=30
OnUnitActiveSec=30
AccuracySec=5s

Note: avoid very low AccuracySec values (e.g. 1ms): they prevent systemd from coalescing wakeups and keep the CPU awake continuously, which is counterproductive on a machine you are monitoring for heat. For a temperature alert, 30-60 s is more than adequate.

Verification and management

systemctl start tempcheck.service        # immediate test run
journalctl -u tempcheck.service -n 20    # logs
systemctl list-timers tempcheck.timer    # next run

The script sends the alert only once when the threshold is exceeded (using the state file) and a recovery message when the temperature returns below the threshold.

Notes

  • Credentials must NOT be placed in the script or committed: keep them in /etc/alertemp.env with 600 permissions.
  • coretemp sensors are generally readable by any user; if you use an unprivileged user, make sure it can write ALERT_FILE.

License

This project is released under the GNU General Public License v3.0 (GPL-3.0). You are free to use, study, modify and redistribute it under the terms of the license, provided WITHOUT ANY WARRANTY. See the LICENSE file or https://www.gnu.org/licenses/gpl-3.0.html.

Consistency note: make sure the repository LICENSE file is GPL-3.0, to align it with the headers present in the sources.

Author

https://github.com/Leproide