Send a Telegram Alert When Your Home Server’s /home Reaches 90% Usage With a Tiny systemd Service and curl

Fri, 16 Oct 2026 09:17:10 +0200

Monitoring /home Usage with a Systemd Timer

A home server rarely needs a full‑blown monitoring stack.
If you just want a quick alert when /home fills up, a tiny systemd service plus curl will do the trick. The example below keeps the footprint minimal, respects security best practices, and uses the official Telegram Bot API.

1. Create a Bot and Grab Credentials

Talk to BotFather on Telegram and create a bot.
Note the bot token (e.g. 123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11).
Find your chat ID by sending a message to the bot and querying https://api.telegram.org/bot<token>/getUpdates.
Store both values in a read‑only file:

sudo mkdir -p /etc/telegram-alert
sudo tee /etc/telegram-alert/credentials <<EOF
TOKEN=123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11
CHAT_ID=987654321
EOF
sudo chmod 600 /etc/telegram-alert/credentials

2. Service Unit – `home-usage-alert.service`

# /etc/systemd/system/home-usage-alert.service
[Unit]
Description=Send Telegram alert when /home exceeds 90%% usage
After=network.target

[Service]
Type=oneshot
EnvironmentFile=/etc/telegram-alert/credentials
ExecStart=/usr/bin/bash -c '
 USAGE=$(df --output=pcent /home | tail -1 | tr -d "%")
 if [ "$USAGE" -ge 90 ]; then
 curl -s -X POST https://api.telegram.org/bot$TOKEN/sendMessage \
 -d chat_id=$CHAT_ID \
 -d text="⚠️ /home is at ${USAGE}%% capacity. Free space needed." \
 -H "Content-Type: application/x-www-form-urlencoded"
 fi
'
PrivateTmp=yes
ProtectSystem=full
RestrictAddressFamilies=AF_INET AF_INET6
Restart=no

[Install]
WantedBy=multi-user.target

Security notes

Telegram on Linux Security

Send a Telegram Alert When Your Home Server’s /home Reaches 90% Usage With a Tiny systemd Service and curl

Monitoring /home Usage with a Systemd Timer

1. Create a Bot and Grab Credentials

2. Service Unit – home-usage-alert.service

Send a Telegram Alert When Your Home Server’s /home Reaches 90% Usage With a Tiny systemd Service and curl

2. Service Unit – `home-usage-alert.service`