man/sd_journal_stream_fd.3

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   2 .TH "SD_JOURNAL_STREAM_FD" "3" "" "systemd 217" "sd_journal_stream_fd"
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   7 .\" http://bugs.debian.org/507673
   8 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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  20 .\" * MAIN CONTENT STARTS HERE *
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  22 .SH "NAME"
  23 sd_journal_stream_fd \- Create log stream file descriptor to the journal
  24 .SH "SYNOPSIS"
  25 .sp
  26 .ft B
  27 .nf
  28 #include <systemd/sd\-journal\&.h>
  29 .fi
  30 .ft
  31 .HP \w'int\ sd_journal_stream_fd('u
  32 .BI "int sd_journal_stream_fd(const\ char\ *" "identifier" ", int\ " "priority" ", int\ " "level_prefix" ");"
  33 .SH "DESCRIPTION"
  34 .PP
  35 \fBsd_journal_stream_fd()\fR
  36 may be used to create a log stream file descriptor\&. Log messages written to this file descriptor as simple newline\-separated text strings are written to the journal\&. This file descriptor can be used internally by applications or be made standard output or standard error of other processes executed\&.
  37 .PP
  38 \fBsd_journal_stream_fd()\fR
  39 takes a short program identifier string as first argument, which will be written to the journal as _SYSLOG_IDENTIFIER= field for each log entry (see
  40 \fBsystemd.journal-fields\fR(7)
  41 for more information)\&. The second argument shall be the default priority level for all messages\&. The priority level is one of
  42 \fBLOG_EMERG\fR,
  43 \fBLOG_ALERT\fR,
  44 \fBLOG_CRIT\fR,
  45 \fBLOG_ERR\fR,
  46 \fBLOG_WARNING\fR,
  47 \fBLOG_NOTICE\fR,
  48 \fBLOG_INFO\fR,
  49 \fBLOG_DEBUG\fR, as defined in
  50 syslog\&.h, see
  51 \fBsyslog\fR(3)
  52 for details\&. The third argument is a boolean: if true kernel\-style log priority level prefixes (such as
  53 \fBSD_WARNING\fR) are interpreted, see
  54 \fBsd-daemon\fR(3)
  55 for more information\&.
  56 .PP
  57 It is recommended that applications log UTF\-8 messages only with this API, but this is not enforced\&.
  58 .SH "RETURN VALUE"
  59 .PP
  60 The call returns a valid write\-only file descriptor on success or a negative errno\-style error code\&.
  61 .SH "NOTES"
  62 .PP
  63 The
  64 \fBsd_journal_stream_fd()\fR
  65 interface is available as a shared library, which can be compiled and linked to with the
  66 \fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
  67 file\&.
  68 .SH "EXAMPLES"
  69 .PP
  70 Creating a log stream suitable for
  71 \fBfprintf\fR(3):
  72 .sp
  73 .if n \{\
  74 .RS 4
  75 .\}
  76 .nf
  77 #include <syslog\&.h>
  78 #include <stdio\&.h>
  79 #include <string\&.h>
  80 #include <unistd\&.h>
  81 #include <systemd/sd\-journal\&.h>
  82 #include <systemd/sd\-daemon\&.h>
  83
  84 int main(int argc, char *argv[]) {
  85         int fd;
  86         FILE *log;
  87         fd = sd_journal_stream_fd("test", LOG_INFO, 1);
  88         if (fd < 0) {
  89                 fprintf(stderr, "Failed to create stream fd: %s\en", strerror(\-fd));
  90                 return 1;
  91         }
  92         log = fdopen(fd, "w");
  93         if (!log) {
  94                 fprintf(stderr, "Failed to create file object: %m\en");
  95                 close(fd);
  96                 return 1;
  97         }
  98         fprintf(log, "Hello World!\en");
  99         fprintf(log, SD_WARNING "This is a warning!\en");
 100         fclose(log);
 101         return 0;
 102 }
 103 .fi
 104 .if n \{\
 105 .RE
 106 .\}
 107 .SH "SEE ALSO"
 108 .PP
 109 \fBsystemd\fR(1),
 110 \fBsd-journal\fR(3),
 111 \fBsd-daemon\fR(3),
 112 \fBsd_journal_print\fR(3),
 113 \fBsyslog\fR(3),
 114 \fBfprintf\fR(3),
 115 \fBsystemd.journal-fields\fR(7)