NAME

       sd_journal_stream_fd - Create log stream file descriptor to the journal

SYNOPSIS

       #include <systemd/sd-journal.h>

       int sd_journal_stream_fd(const char* identifier, int priority, int level_prefix);

DESCRIPTION

       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 messages only with this API, but this is not
       enforced.

RETURN VALUE

       The call returns a valid write-only file descriptor on success or a negative errno-style
       error code.

NOTES

       The sd_journal_stream_fd() interface is available as shared library, which can be compiled
       and linked to with the libsystemd-journalpkg-config(1) file.

EXAMPLES

       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;
           }

SEE ALSO

       systemd(1), sd-journal(3), sd-daemon(3), sd_journal_print(3), syslog(3), fprintf(3),
       systemd.journal-fields(7)