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```{index} single: Sys::Syslog
```

# Sys::Syslog

```{pperl-module-badges} Sys::Syslog
```

Messages to the system log: syslog(3) from Perl.

This is Sys::Syslog 0.36; `Sys/Syslog.pm` is upstream's and is the
interface. It sends a message by the first mechanism that works - the
C library's syslog(3) ("native", these XSUBs), a UNIX socket, TCP,
UDP, the console - and formats it, `printf`-style.

## Synopsis

```perl
use Sys::Syslog qw(:standard :macros);

openlog('myprog', 'ndelay,pid', LOG_USER);   # ident, options, facility
syslog(LOG_INFO, 'started with %d workers', 4);
syslog('warning', 'disk %s at %d%%', '/var', 91);   # levels by name too
setlogmask(LOG_UPTO(LOG_NOTICE));             # drop info and debug
closelog();
```

## The functions, written in Perl

`:standard` exports the first four:

- `openlog($ident, $options, $facility)` - name the program, choose
  options (`cons`, `ndelay`, `nofatal`, `perror`, `pid`), and the
  default facility (`LOG_USER`, `LOG_DAEMON`, `LOG_LOCAL0`..`LOG_LOCAL7`,
  ...). Optional: `syslog` opens with defaults.
- `syslog($priority, $format, @args)` - one message; `$priority` is
  a level (`LOG_ERR`, `"err"`, ...), optionally with a facility
  (`"local0|info"`, `LOG_LOCAL0 | LOG_INFO`).
- `setlogmask($mask)` - which levels get through; returns the old mask.
- `closelog()`.
- `setlogsock($type)` (`:extended`) - choose the mechanism: `native`,
  `unix`, `tcp`, `udp`, `stream`, `pipe`, `console`.

`:macros` exports the levels (`LOG_EMERG` .. `LOG_DEBUG`), the
facilities, the option flags (`LOG_PID`, `LOG_NDELAY`, ...),
`LOG_MASK` and `LOG_UPTO`.

## Differences from upstream

None: upstream's tests pass unchanged (t/81-xs-native/Sys-Syslog, the
`upstream` files), and 010-constants.t checks every constant against
perl 5.44.

## Functions

### Masks

#### `LOG_MASK`

The `setlogmask` bit of one level: `setlogmask(LOG_MASK(LOG_ERR))` lets only errors through. Exported with `:macros`.

#### `LOG_UPTO`

The `setlogmask` bits of a level and every more urgent one: `setlogmask(LOG_UPTO(LOG_WARNING))` drops notices, informational and debug messages. Exported with `:macros`.

### Priority values

#### `LOG_FAC`

The facility number of a combined priority value: `LOG_FAC(134)` is 16 for `LOG_LOCAL0` (whose value is 16 << 3). Not exported; call it as `Sys::Syslog::LOG_FAC`.

#### `LOG_PRI`

The level part of a combined priority value: `LOG_PRI(134)` is 6, `LOG_INFO`. Not exported; call it as `Sys::Syslog::LOG_PRI`.

#### `LOG_MAKEPRI`

A combined priority value from a facility and a level: `LOG_MAKEPRI(LOG_LOCAL0, LOG_INFO)` is 134. Not exported; call it as `Sys::Syslog::LOG_MAKEPRI`.