sd_journal_stream_fd — Create log stream file descriptor to the journal
#include <systemd/sd-journal.h>
int sd_journal_stream_fd( | const char* identifier, |
int priority, | |
int level_prefix) ; |
sd_journal_stream_fd()
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 STDOUT/STDERR of other
processes executed.
sd_journal_stream_fd()
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
systemd.journal-fields(7)
for more information). The second argument shall be
the default priority level for all messages. The
priority level is one of LOG_EMERG
,
LOG_ALERT
,
LOG_CRIT
,
LOG_ERR
,
LOG_WARNING
,
LOG_NOTICE
,
LOG_INFO
,
LOG_DEBUG
, as defined in
syslog.h
, see
syslog(3)
for details. The third argument is a boolean: if true
kernel-style log priority level prefixes (such as
SD_WARNING
) are interpreted, see
sd-daemon(3)
for more information.
It is recommended that applications log UTF-8 mesages only with this API, but this is not enforced.
The call returns a valid write-only file descriptor on success or a negative errno-style error code.
The sd_journal_stream_fd()
interface is available as shared library, which can
be compiled and linked to with the
libsystemd-journal
pkg-config(1)
file.
Creating a log stream suitable for fprintf(3):
#include <syslog.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <systemd/sd-journal.h> #include <systemd/sd-daemon.h> int main(int argc, char *argv[]) { int fd; FILE *log; fd = sd_journal_stream_fd("test", LOG_INFO, 1); if (fd < 0) { fprintf(stderr, "Failed to create stream fd: %s\n", strerror(-fd)); return 1; } log = fdopen(fd, "w"); if (!log) { fprintf(stderr, "Failed to create file object: %m\n"); close(fd); return 1; } fprintf(log, "Hello World!\n"); fprintf(log, SD_WARNING "This is a warning!\n"); fclose(log); return 0; }