sd_journal_stream_fd

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## 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 standard output or standard error 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 a shared library, which can be compiled and linked to with the `libsystemd` pkg-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)