'\" t
.\"     Title: sd-daemon
.\"    Author: Lennart Poettering <lennart@poettering.net>
.\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
.\"      Date: 03/16/2012
.\"    Manual: sd-daemon
.\"    Source: systemd
.\"  Language: English
.\"
.TH "SD\-DAEMON" "7" "03/16/2012" "systemd" "sd-daemon"
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.SH "NAME"
sd-daemon \- Reference implementation of APIs for new\-style daemons
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <systemd/sd\-daemon\&.h>
.fi
.ft
.HP \w'\fBpkg\-config\ \-\-cflags\ \-\-libs\ libsystemd\-daemon\fR\ 'u
\fBpkg\-config \-\-cflags \-\-libs libsystemd\-daemon\fR
.SH "DESCRIPTION"
.PP
sd\-daemon\&.c
and
sd\-daemon\&.h
provide a reference implementation of various APIs for new\-style daemons, as implemented by the
\fBsystemd\fR(1)
init system\&.
.PP
See
\fBsd_listen_fds\fR(3),
\fBsd_notify\fR(3),
\fBsd_booted\fR(3),
\fBsd_is_fifo\fR(3)
for more information about the functions implemented\&. In addition to these functions a couple of logging prefixes are defined as macros:
.sp
.if n \{\
.RS 4
.\}
.nf
#define SD_EMERG   "<0>"  /* system is unusable */
#define SD_ALERT   "<1>"  /* action must be taken immediately */
#define SD_CRIT    "<2>"  /* critical conditions */
#define SD_ERR     "<3>"  /* error conditions */
#define SD_WARNING "<4>"  /* warning conditions */
#define SD_NOTICE  "<5>"  /* normal but significant condition */
#define SD_INFO    "<6>"  /* informational */
#define SD_DEBUG   "<7>"  /* debug\-level messages */
.fi
.if n \{\
.RE
.\}
.PP
These prefixes are intended to be used in conjunction with STDERR\-based logging as implemented by systemd\&. If a systemd service definition file is configured with
\fIStandardError=syslog\fR
or
\fIStandardError=kmsg\fR
these prefixes can be used to encode a log level in lines printed\&. This is similar to the kernel
\fBprintk()\fR\-style logging\&. See
\fBklogctl\fR(2)
for more information\&.
.PP
The log levels are identical to
\fBsyslog\fR(3)\*(Aqs log level system\&. To use these prefixes simply prefix every line with one of these strings\&. A line that is not prefixed will be logged at the default log level SD_INFO\&.
.PP
\fBExample\ \&1.\ \&Hello World\fR
.PP
A daemon may log with the log level NOTICE by issuing this call:
.sp
.if n \{\
.RS 4
.\}
.nf
fprintf(stderr, SD_NOTICE "Hello World!\en");
.fi
.if n \{\
.RE
.\}
.SH "NOTES"
.PP
These interfaces are provided by the reference implementation of APIs for new\-style daemons and distributed with the systemd package\&. The algorithms they implement are simple, and can easily be reimplemented in daemons if it is important to support this interface without using the reference implementation\&. See the respective function man pages for details\&.
.PP
In addition, for details about the algorithms check the liberally licensed reference implementation sources:
\m[blue]\fB\%http://cgit.freedesktop.org/systemd/systemd/plain/src/sd-daemon.c\fR\m[]
resp\&.
\m[blue]\fB\%http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h\fR\m[]
.PP
These APIs are implemented in the reference implementation\*(Aqs
sd\-daemon\&.c
and
sd\-daemon\&.h
files\&. These interfaces are available as shared library, which can be compiled and linked to with the
libsystemd\-daemon
\fBpkg-config\fR(1)
file\&. Alternatively, applications consuming these APIs may copy the implementation into their source tree, either verbatim or in excerpts\&.
.PP
The functions directly related to new\-style daemons become NOPs when \-DDISABLE_SYSTEMD is set during compilation and the reference implementation is used as drop\-in files\&. In addition, if
sd\-daemon\&.c
is compiled on non\-Linux systems they become NOPs\&.
.SH "SEE ALSO"
.PP

\fBsystemd\fR(1),
\fBsd_listen_fds\fR(3),
\fBsd_notify\fR(3),
\fBsd_booted\fR(3),
\fBsd_is_fifo\fR(3),
\fBdaemon\fR(7),
\fBsystemd.service\fR(5),
\fBsystemd.socket\fR(5),
\fBfprintf\fR(3),
\fBsd-readahead\fR(7),
\fBpkg-config\fR(1)
.SH "AUTHOR"
.PP
\fBLennart Poettering\fR <\&lennart@poettering\&.net\&>
.RS 4
Developer
.RE