sd_journal_print

SD_JOURNAL_PRINT(3)             sd_journal_print             SD_JOURNAL_PRINT(3)



NAME
       sd_journal_print, sd_journal_printv, sd_journal_send, sd_journal_sendv,
       sd_journal_perror, SD_JOURNAL_SUPPRESS_LOCATION,
       sd_journal_print_with_location, sd_journal_printv_with_location,
       sd_journal_send_with_location, sd_journal_sendv_with_location,
       sd_journal_perror_with_location - Submit log entries to the journal

SYNOPSIS
       #include <systemd/sd-journal.h>

       int sd_journal_print(int priority, const char *format, ...);

       int sd_journal_printv(int priority, const char *format, va_list ap);

       int sd_journal_send(const char *format, ...);

       int sd_journal_sendv(const struct iovec *iov, int n);

       int sd_journal_perror(const char *message);

       int sd_journal_print_with_location(const char *file, const char *line,
                                          const char *func, int priority,
                                          const char *format, ...);

       int sd_journal_printv_with_location(int priority, const char *file,
                                           const char *line, const char *func,
                                           const char *format, va_list ap);

       int sd_journal_send_with_location(const char *file, const char *line,
                                         const char *func, const char *format,
                                         ...);

       int sd_journal_sendv_with_location(const char *file, const char *line,
                                          const char *func,
                                          const struct iovec *iov, int n);

       int sd_journal_perror_with_location(const char *file, const char *line,
                                           const char *func,
                                           const char *message);

DESCRIPTION
       sd_journal_print() may be used to submit simple, plain text log entries
       to the system journal. The first argument is a priority value. This is
       followed by a format string and its parameters, similar to printf(3) or
       syslog(3). Note that currently the resulting message will be truncated to
       LINE_MAX - 8. The priority value 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. It is recommended to use
       this call to submit log messages in the application locale or system
       locale and in UTF-8 format, but no such restrictions are enforced. Note
       that log messages written using this function are generally not expected
       to end in a new-line character. However, as all trailing whitespace
       (including spaces, new-lines, tabulators and carriage returns) are
       automatically stripped from the logged string, it is acceptable to
       specify one (or more). Empty lines (after trailing whitespace removal)
       are suppressed. On non-empty lines, leading whitespace (as well as inner
       whitespace) is left unmodified.

       sd_journal_printv() is similar to sd_journal_print() but takes a variable
       argument list encapsulated in an object of type va_list (see stdarg(3)
       for more information) instead of the format string. It is otherwise
       equivalent in behavior.

       sd_journal_send() may be used to submit structured log entries to the
       system journal. It takes a series of format strings, each immediately
       followed by their associated parameters, terminated by NULL. The strings
       passed should be of the format "VARIABLE=value". The variable name must
       be in uppercase and consist only of characters, numbers and underscores,
       and may not begin with an underscore. (All assignments that do not follow
       this syntax will be ignored.) The value can be of any size and format. It
       is highly recommended to submit text strings formatted in the UTF-8
       character encoding only, and submit binary fields only when formatting in
       UTF-8 strings is not sensible. A number of well-known fields are defined,
       see systemd.journal-fields(7) for details, but additional application
       defined fields may be used. A variable may be assigned more than one
       value per entry. If this function is used, trailing whitespace is
       automatically removed from each formatted field.

       sd_journal_sendv() is similar to sd_journal_send() but takes an array of
       struct iovec (as defined in uio.h, see readv(3) for details) instead of
       the format string. Each structure should reference one field of the entry
       to submit. The second argument specifies the number of structures in the
       array.  sd_journal_sendv() is particularly useful to submit binary
       objects to the journal where that is necessary. Note that this function
       will not strip trailing whitespace of the passed fields, but passes the
       specified data along unmodified. This is different from both
       sd_journal_print() and sd_journal_send() described above, which are based
       on format strings, and do strip trailing whitespace.

       sd_journal_perror() is a similar to perror(3) and writes a message to the
       journal that consists of the passed string, suffixed with ": " and a
       human-readable representation of the current error code stored in
       errno(3). If the message string is passed as NULL or empty string, only
       the error string representation will be written, prefixed with nothing.
       An additional journal field ERRNO= is included in the entry containing
       the numeric error code formatted as decimal string. The log priority used
       is LOG_ERR (3).

       Note that sd_journal_send() is a wrapper around sd_journal_sendv() to
       make it easier to use when only text strings shall be submitted. Also,
       the following two calls are mostly equivalent:

           sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid());

           sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(),
                           "PRIORITY=%i", LOG_INFO,
                           NULL);

       Note that these calls implicitly add fields for the source file, function
       name and code line where invoked. This is implemented with macros. If
       this is not desired, it can be turned off by defining
       SD_JOURNAL_SUPPRESS_LOCATION before including sd-journal.h.

       sd_journal_print_with_location(), sd_journal_printv_with_location(),
       sd_journal_send_with_location(), sd_journal_sendv_with_location(), and
       sd_journal_perror_with_location() are similar to their counterparts
       without "_with_location", but accept additional parameters to explicitly
       set the source file name, function, and line. Those arguments must
       contain valid journal entries including the variable name, e.g.
       "CODE_FILE=src/foo.c", "CODE_LINE=666", "CODE_FUNC=myfunc". These
       variants are primarily useful when writing custom wrappers, for example
       in bindings for a different language.

       syslog(3) and sd_journal_print() may largely be used interchangeably
       functionality-wise. However, note that log messages logged via the former
       take a different path to the journal server than the later, and hence
       global chronological ordering between the two streams cannot be
       guaranteed. Using sd_journal_print() has the benefit of logging source
       code line, filenames, and functions as metadata along all entries, and
       guaranteeing chronological ordering with structured log entries that are
       generated via sd_journal_send(). Using syslog() has the benefit of being
       more portable.

RETURN VALUE
       The ten functions return 0 on success or a negative errno-style error
       code. The errno(3) variable itself is not altered.

       If systemd-journald(8) is not running (the socket is not present), those
       functions do nothing, and also return 0.

THREAD SAFETY
       All functions listed here are thread-safe and may be called in parallel
       from multiple threads.

       sd_journal_sendv() and sd_journal_sendv_with_location() are "async signal
       safe" in the meaning of signal-safety(7).

       sd_journal_print(), sd_journal_printv(), sd_journal_send(),
       sd_journal_perror(), and their counterparts with "_with_location" are not
       async signal safe.

NOTES
       These APIs are implemented as a shared library, which can be compiled and
       linked to with the libsystemd pkg-config(1) file.

SEE ALSO
       systemd(1), sd-journal(3), sd_journal_stream_fd(3), syslog(3), perror(3),
       errno(3), systemd.journal-fields(7), signal(7), socket(7)



systemd 247                                                  SD_JOURNAL_PRINT(3)