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123 lines
4.5 KiB
Groff
123 lines
4.5 KiB
Groff
'\" t
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.TH "SD\-DAEMON" "3" "" "systemd 208" "sd-daemon"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.SH "NAME"
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sd-daemon, SD_EMERG, SD_ALERT, SD_CRIT, SD_ERR, SD_WARNING, SD_NOTICE, SD_INFO, SD_DEBUG \- Reference implementation of APIs for new\-style daemons
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.SH "SYNOPSIS"
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.sp
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.ft B
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.nf
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#include <systemd/sd\-daemon\&.h>
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.fi
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.ft
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.HP \w'\fBpkg\-config\ \-\-cflags\ \-\-libs\ libsystemd\-daemon\fR\ 'u
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\fBpkg\-config \-\-cflags \-\-libs libsystemd\-daemon\fR
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.SH "DESCRIPTION"
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.PP
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sd\-daemon\&.c
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and
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sd\-daemon\&.h
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provide a reference implementation of various APIs for new\-style daemons, as implemented by the
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\fBsystemd\fR(1)
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init system\&.
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.PP
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See
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\fBsd_listen_fds\fR(3),
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\fBsd_notify\fR(3),
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\fBsd_booted\fR(3),
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\fBsd_is_fifo\fR(3)
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for more information about the functions implemented\&. In addition to these functions a couple of logging prefixes are defined as macros:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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#define SD_EMERG "<0>" /* system is unusable */
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#define SD_ALERT "<1>" /* action must be taken immediately */
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#define SD_CRIT "<2>" /* critical conditions */
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#define SD_ERR "<3>" /* error conditions */
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#define SD_WARNING "<4>" /* warning conditions */
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#define SD_NOTICE "<5>" /* normal but significant condition */
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#define SD_INFO "<6>" /* informational */
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#define SD_DEBUG "<7>" /* debug\-level messages */
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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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
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\fIStandardError=syslog\fR
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or
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\fIStandardError=kmsg\fR, these prefixes can be used to encode a log level in lines printed\&. This is similar to the kernel
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\fBprintk()\fR\-style logging\&. See
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\fBklogctl\fR(2)
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for more information\&.
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.PP
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The log levels are identical to
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\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\&.
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.PP
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\fBExample\ \&1.\ \&Hello World\fR
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.PP
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A daemon may log with the log level NOTICE by issuing this call:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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fprintf(stderr, SD_NOTICE "Hello World!\en");
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.fi
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.if n \{\
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.RE
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.\}
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.SH "NOTES"
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.PP
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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\&.
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.PP
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In addition, for details about the algorithms check the liberally licensed reference implementation sources:
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\m[blue]\fB\%http://cgit.freedesktop.org/systemd/systemd/plain/src/libsystemd-daemon/sd-daemon.c\fR\m[]
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and
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\m[blue]\fB\%http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h\fR\m[]
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.PP
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These APIs are implemented in the reference implementation\*(Aqs
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sd\-daemon\&.c
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and
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sd\-daemon\&.h
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files\&. These interfaces are available as shared library, which can be compiled and linked to with the
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\fBlibsystemd\-daemon\fR\ \&\fBpkg-config\fR(1)
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file\&. Alternatively, applications consuming these APIs may copy the implementation into their source tree, either verbatim or in excerpts\&.
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.PP
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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
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sd\-daemon\&.c
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is compiled on non\-Linux systems they become NOPs\&.
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.SH "SEE ALSO"
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.PP
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\fBsystemd\fR(1),
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\fBsd_listen_fds\fR(3),
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\fBsd_notify\fR(3),
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\fBsd_booted\fR(3),
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\fBsd_is_fifo\fR(3),
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\fBdaemon\fR(7),
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\fBsystemd.service\fR(5),
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\fBsystemd.socket\fR(5),
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\fBfprintf\fR(3),
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\fBsd-readahead\fR(3),
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\fBpkg-config\fR(1)
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