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journald-native/README.md

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# journald-native
[![Build Status](https://travis-ci.org/theforeman/journald-native.svg?branch=master)](https://travis-ci.org/theforeman/journald-native)
A systemd-journal native logging lib wrapper.
[See sd-journal help for more info](http://www.freedesktop.org/software/systemd/man/sd_journal_print.html)
## Installation
Run
```sh
gem install journald-native
```
or add
```ruby
gem 'journald-native', '~> 1.0.11'
```
to your Gemfile.
Please note that you need a systemd development package installed in your system like `systemd-devel` in Fedora, `libsystemd-dev` in Debian, also may be a separate package for journal in older systems like `libsystemd-journal-dev`.
**NB:** The gem can be installed on non-linux system but it will do nothing there. (Functions will return success without any actual effect)
## Usage
```ruby
require 'journald/native'
```
### Constants
Constants are used to denote a log level
Available constants:
```ruby
Journald::LOG_EMERG # system is unusable
Journald::LOG_ALERT # action must be taken immediately
Journald::LOG_CRIT # critical conditions
Journald::LOG_ERR # error conditions
Journald::LOG_WARNING # warning conditions
Journald::LOG_NOTICE # normal but significant condition
Journald::LOG_INFO # informational
Journald::LOG_DEBUG # debug-level messages
```
systemd-journal uses syslog constants to denote level therefore they are equal to those of the Syslog module,
e.g. ```Journald::LOG_WARNING == Syslog::LOG_WARNING```.
[See syslog man page for more info](http://man7.org/linux/man-pages/man3/syslog.3.html)
### Methods
Methods of Journald::Native class wrap systemd-journal calls.
[See sd-journal help for more info](http://www.freedesktop.org/software/systemd/man/sd_journal_print.html)
```ruby
Journald::Native.sd_journal_send "MESSAGE=message", "PRIORITY=#{Journald::LOG_WARNING}"
Journald::Native.sd_journal_print Journald::LOG_WARNING, "message"
Journald::Native.sd_journal_perror "message"
```
It is not recommended to use `sd_journal_print` and `sd_journal_perror` as you may get exception
if your string contains `'\0'` byte due to C zero-terminated string format.
On the contrary `sd_journal_send` uses binary buffers and does not have this shortcoming.
### Short aliases
Versions prior to 1.0.11 used short function names that are available now as aliases.
They will probably throw a deprecation warning in 1.1 and be removed in 2.0 should these versions ever happen.
`Journald::Native.sd_journal_send` can be called as `Journald::Native.send`
`Journald::Native.sd_journal_print` can be called as `Journald::Native.print`
`Journald::Native.sd_journal_perror` can be called as `Journald::Native.perror`
**Please note that `send` method is overridden.
This is a bad practice and a reason why longer names were introduced later**
### Authors
This library was written by Anton Smirnov and currently maintained by https://www.theforeman.org developers.
### License
Copyright (c) 2014 Anton Smirnov
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You can find a copy of the GNU Lesser General Public License
in COPYING.md or at <https://www.gnu.org/licenses/lgpl-2.1.txt>.