# Channels occupancy subscribe
Use the `ably channels occupancy subscribe` command to subscribe to occupancy updates on an Ably Pub/Sub channel.
## Synopsis
### Shell
```
ably channels occupancy subscribe [options]
```
## Arguments
### `channel-name` **(Required)**
The name of the channel to subscribe to occupancy updates on.
## Options
### `--duration | -D`
The duration in seconds to subscribe for before automatically unsubscribing.
### `--client-id`
A client ID to use when subscribing.
### `--json`
Output results as compact JSON. Mutually exclusive with `--pretty-json`.
### `--pretty-json`
Output results in formatted JSON. Mutually exclusive with `--json`.
### `--verbose | -v`
Enable verbose logging. Can be combined with `--json` or `--pretty-json`.
## Examples
Subscribe to occupancy updates:
### Shell
```
ably channels occupancy subscribe my-channel
```
Subscribe for a specific duration:
### Shell
```
ably channels occupancy subscribe my-channel --duration 60
```
Subscribe to occupancy using an API key environment variable:
### Shell
```
ABLY_API_KEY="YOUR_API_KEY" ably channels occupancy subscribe my-channel
```
Subscribe to occupancy updates in JSON format:
### Shell
```
ably channels occupancy subscribe my-channel --json
```
Subscribe to occupancy updates in formatted JSON:
### Shell
```
ably channels occupancy subscribe my-channel --pretty-json
```
## See also
* [Channels](https://ably.com/docs/cli/channels.md) — Explore all `ably channels` commands.
* [CLI reference](https://ably.com/docs/cli.md) — Full list of available commands.
## Related Topics
- [get](https://ably.com/docs/cli/channels/occupancy/get.md): Get current occupancy for an Ably Pub/Sub channel using the CLI.
## Documentation Index
To discover additional Ably documentation:
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