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Subscribe via ntfy CLI

In addition to subscribing via the web UI, the phone app, or the API, you can subscribe to topics via the ntfy CLI. The CLI is included in the same ntfy binary that can be used to self-host a server.

Info

The ntfy CLI is not required to send or receive messages. You can instead send messages with curl, and even use it to subscribe to topics. It may be a little more convenient to use the ntfy CLI than writing your own script. It all depends on the use case. 😀

Install + configure

To install the ntfy CLI, simply follow the steps outlined on the install page. The ntfy server and client are the same binary, so it's all very convenient. After installing, you can (optionally) configure the client by creating ~/.config/ntfy/client.yml (for the non-root user), or /etc/ntfy/client.yml (for the root user). You can find a skeleton config on GitHub.

If you just want to use ntfy.sh, you don't have to change anything. If you self-host your own server, you may want to edit the default-host option:

# Base URL used to expand short topic names in the "ntfy publish" and "ntfy subscribe" commands.
# If you self-host a ntfy server, you'll likely want to change this.
#
default-host: https://ntfy.myhost.com

Publish messages

You can send messages with the ntfy CLI using the ntfy publish command (or any of its aliases pub, send or trigger). There are a lot of examples on the page about publishing messages, but here are a few quick ones:

ntfy publish mytopic This is a message
ntfy publish mytopic "This is a message"
ntfy pub mytopic "This is a message" 
ntfy publish \
    --title="Thing sold on eBay" \
    --priority=high \
    --tags=partying_face \
    mytopic \
    "Somebody just bought the thing that you sell"
ntfy pub --at=8:30am delayed_topic Laterzz
ntfy trigger mywebhook
ntfy pub mywebhook

Subscribe to topics

You can subscribe to topics using ntfy subscribe. Depending on how it is called, this command will either print or execute a command for every arriving message. There are a few different ways in which the command can be run:

Stream messages as JSON

ntfy subscribe TOPIC
If you run the command like this, it prints the JSON representation of every incoming message. This is useful when you have a command that wants to stream-read incoming JSON messages. Unless --poll is passed, this command stays open forever.

$ ntfy sub mytopic
{"id":"nZ8PjH5oox","time":1639971913,"event":"message","topic":"mytopic","message":"hi there"}
{"id":"sekSLWTujn","time":1639972063,"event":"message","topic":"mytopic",priority:5,"message":"Oh no!"}
...
Subscribe in JSON mode

Run command for every message

ntfy subscribe TOPIC COMMAND
If you run it like this, a COMMAND is executed for every incoming messages. Scroll down to see a list of available environment variables. Here are a few examples:

ntfy sub mytopic 'notify-send "$m"'
ntfy sub topic1 /my/script.sh
ntfy sub topic1 'echo "Message $m was received. Its title was $t and it had priority $p'
Execute command on incoming messages

The message fields are passed to the command as environment variables and can be used in scripts. Note that since these are environment variables, you typically don't have to worry about quoting too much, as long as you enclose them in double-quotes, you should be fine:

Variable Aliases Description
$NTFY_ID $id Unique message ID
$NTFY_TIME $time Unix timestamp of the message delivery
$NTFY_TOPIC $topic Topic name
$NTFY_MESSAGE $message, $m Message body
$NTFY_TITLE $title, $t Message title
$NTFY_PRIORITY $priority, $prio, $p Message priority (1=min, 5=max)
$NTFY_TAGS $tags, $tag, $ta Message tags (comma separated list)
$NTFY_RAW $raw Raw JSON message

Subscribe to multiple topics

ntfy subscribe --from-config
To subscribe to multiple topics at once, and run different commands for each one, you can use ntfy subscribe --from-config, which will read the subscribe config from the config file. Please also check out the ntfy-client systemd service.

Here's an example config file that subscribes to three different topics, executing a different command for each of them:

subscribe:
- topic: echo-this
  command: 'echo "Message received: $message"'
- topic: alerts
  command: notify-send -i /usr/share/ntfy/logo.png "Important" "$m"
  if:
    priority: high,urgent
- topic: calc
  command: 'gnome-calculator 2>/dev/null &'
- topic: print-temp
  command: |
        echo "You can easily run inline scripts, too."
        temp="$(sensors | awk '/Pack/ { print substr($4,2,2) }')"
        if [ $temp -gt 80 ]; then
          echo "Warning: CPU temperature is $temp. Too high."
        else
          echo "CPU temperature is $temp. That's alright."
        fi

In this example, when ntfy subscribe --from-config is executed:

  • Messages to echo-this simply echos to standard out
  • Messages to alerts display as desktop notification for high priority messages using notify-send
  • Messages to calc open the gnome calculator 😀 (because, why not)
  • Messages to print-temp execute an inline script and print the CPU temperature

I hope this shows how powerful this command is. Here's a short video that demonstrates the above example:

Execute all the things

Using the systemd service

You can use the ntfy-client systemd service (see ntfy-client.service) to subscribe to multiple topics just like in the example above. The service is automatically installed (but not started) if you install the deb/rpm package. To configure it, simply edit /etc/ntfy/client.yml and run sudo systemctl restart ntfy-client.

Info

The ntfy-client.service runs as user ntfy, meaning that typical Linux permission restrictions apply. See below for how to fix this.

If the service runs on your personal desktop machine, you may want to override the service user/group (User= and Group=), and adjust the DISPLAY and DBUS_SESSION_BUS_ADDRESS environment variables. This will allow you to run commands in your X session as the primary machine user.

You can either manually override these systemd service entries with sudo systemctl edit ntfy-client, and add this (assuming your user is phil). Don't forget to run sudo systemctl daemon-reload and sudo systemctl restart ntfy-client after editing the service file:

[Service]
User=phil
Group=phil
Environment="DISPLAY=:0" "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus"

Or you can run the following script that creates this override config for you:

sudo sh -c 'cat > /etc/systemd/system/ntfy-client.service.d/override.conf' <<EOF
[Service]
User=$USER
Group=$USER
Environment="DISPLAY=:0" "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/$(id -u)/bus"
EOF

sudo systemctl daemon-reload
sudo systemctl restart ntfy-client