The `CLIENT LIST` command returns information and statistics about the client
connections server in a mostly human readable format.

As of v5.0, the optional `TYPE type` subcommand can be used to filter the list
by clients' type, where _type_ is one of `normal`, `master`, `replica` and
`pubsub`. Note that clients blocked into the `MONITOR` command are considered to
belong to the `normal` class.

@return

@bulk-string-reply: a unique string, formatted as follows:

- One client connection per line (separated by LF)
- Each line is composed of a succession of `property=value` fields separated by
  a space character.

Here is the meaning of the fields:

- `id`: an unique 64-bit client ID (introduced in Redis 2.8.12).
- `name`: the name set by the client with `CLIENT SETNAME`
- `addr`: address/port of the client
- `fd`: file descriptor corresponding to the socket
- `age`: total duration of the connection in seconds
- `idle`: idle time of the connection in seconds
- `flags`: client flags (see below)
- `db`: current database ID
- `sub`: number of channel subscriptions
- `psub`: number of pattern matching subscriptions
- `multi`: number of commands in a MULTI/EXEC context
- `qbuf`: query buffer length (0 means no query pending)
- `qbuf-free`: free space of the query buffer (0 means the buffer is full)
- `obl`: output buffer length
- `oll`: output list length (replies are queued in this list when the buffer is
  full)
- `omem`: output buffer memory usage
- `events`: file descriptor events (see below)
- `cmd`: last command played

The client flags can be a combination of:

```
A: connection to be closed ASAP
b: the client is waiting in a blocking operation
c: connection to be closed after writing entire reply
d: a watched keys has been modified - EXEC will fail
i: the client is waiting for a VM I/O (deprecated)
M: the client is a master
N: no specific flag set
O: the client is a client in MONITOR mode
P: the client is a Pub/Sub subscriber
r: the client is in readonly mode against a cluster node
S: the client is a replica node connection to this instance
u: the client is unblocked
U: the client is connected via a Unix domain socket
x: the client is in a MULTI/EXEC context
```

The file descriptor events can be:

```
r: the client socket is readable (event loop)
w: the client socket is writable (event loop)
```

## Notes

New fields are regularly added for debugging purpose. Some could be removed in
the future. A version safe Redis client using this command should parse the
output accordingly (i.e. handling gracefully missing fields, skipping unknown
fields).