# `NervesLogging`
[🔗](https://github.com/nerves-project/nerves_logging/blob/v0.2.4/lib/nerves_logging.ex#L5)

NervesLogging forwards log messages from the Linux kernel and syslog to the Elixir logger

Log messages have the following additional metadata:

* `:facility` - the facility of the log message
* `:application` - either `:$kmsg` or `:$syslog`

See the [Elixir Logger documentation](https://hexdocs.pm/logger/Logger.html) for
reducing what's logged if the system logs become too noisy. Some examples:

```elixir
# Reduce logging for both syslog and kernel logs
Logger.put_application_level(:nerves_logging, :error)

# Adjust logging for kernel logs
Logger.put_module_level(NervesLogging.KmsgTailer, :error)

# Adjust logging for syslog logs
Logger.put_module_level(NervesLogging.SyslogTailer, :error)
```

This library is not an OTP application so its log tailers must be added to
a supervision tree. This is handled by `Nerves.Runtime` for Nerves devices.

# `facility`

```elixir
@type facility() ::
  :kernel
  | :user_level
  | :mail
  | :system
  | :security_authorization
  | :syslogd
  | :line_printer
  | :network_news
  | :UUCP
  | :clock
  | :security_authorization
  | :FTP
  | :NTP
  | :log_audit
  | :log_alert
  | :clock
  | :local0
  | :local1
  | :local2
  | :local3
  | :local4
  | :local5
  | :local6
  | :local7
```

Syslog facilities

See https://tools.ietf.org/html/rfc5424#section-6.2.1 for the list.

# `severity`

```elixir
@type severity() :: Logger.level()
```

Syslog severity levels

These map 1:1 to `Logger.level/0` values.

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*Consult [api-reference.md](api-reference.md) for complete listing*