'\" t
.TH "SD\-DAEMON" "3" "" "systemd 256.7" "sd-daemon"
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.SH "NAME"
sd-daemon, SD_EMERG, SD_ALERT, SD_CRIT, SD_ERR, SD_WARNING, SD_NOTICE, SD_INFO, SD_DEBUG \- 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\fR\ 'u
\fBpkg\-config \-\-cflags \-\-libs libsystemd\fR
.SH "DESCRIPTION"
.PP
sd\-daemon\&.h
is part of
\fBlibsystemd\fR(3)
and provides APIs for new\-style daemons, as implemented by the
\fBsystemd\fR(1)
service manager\&.
.PP
See
\fBsd_listen_fds\fR(3),
\fBsd_notify\fR(3),
\fBsd_booted\fR(3),
\fBsd_is_fifo\fR(3),
\fBsd_watchdog_enabled\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 (or stdout\-based logging) as implemented by systemd\&. If a systemd service definition file is configured with
\fIStandardError=journal\fR
or
\fIStandardError=kmsg\fR
(and similar with
\fIStandardOutput=\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
Functions described here are available as a shared library, which can be compiled against and linked to with the
\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
file\&.
.PP
The code described here uses
\fBgetenv\fR(3), which is declared to be not multi\-thread\-safe\&. This means that the code calling the functions described here must not call
\fBsetenv\fR(3)
from a parallel thread\&. It is recommended to only do calls to
\fBsetenv()\fR
from an early phase of the program when no other threads have been started\&.
.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), \fBsd_watchdog_enabled\fR(3), \fBdaemon\fR(7), \fBsystemd.service\fR(5), \fBsystemd.socket\fR(5), \fBfprintf\fR(3), \fBpkg-config\fR(1)