plucky (3) sd-journal.3.gz

NAME

       sd-journal - APIs for submitting and querying log entries to and from the journal

SYNOPSIS

       #include <systemd/sd-journal.h>

       pkg-config --cflags --libs libsystemd

DESCRIPTION

       sd-journal.h is part of libsystemd(3) and provides APIs to submit and query log entries. The APIs exposed
       act both as client for the systemd-journald.service(8) journal service and as parser for the journal
       files on disk.

       See sd_journal_print(3), sd_journal_stream_fd(3), sd_journal_open(3), sd_journal_next(3),
       sd_journal_get_realtime_usec(3), sd_journal_add_match(3), sd_journal_seek_head(3),
       sd_journal_enumerate_fields(3), sd_journal_get_cursor(3), sd_journal_get_cutoff_realtime_usec(3),
       sd_journal_get_cutoff_monotonic_usec(3), sd_journal_get_usage(3), sd_journal_get_catalog(3),
       sd_journal_get_fd(3), sd_journal_has_runtime_files(3) and sd_journal_has_persistent_files(3) for more
       information about the functions implemented.

       Command line access for submitting entries to the journal is available with the systemd-cat(1) tool.
       Command line access for querying entries from the journal is available with the journalctl(1) tool.

THREAD SAFETY

       Functions that operate on sd_journal objects are thread agnostic — given sd_journal pointer may only be
       used from one specific thread at all times (and it has to be the very same one during the entire lifetime
       of the object), but multiple, independent threads may use multiple, independent objects safely. Other
       functions — those that are used to send entries to the journal, like sd_journal_print(3) and similar, or
       those that are used to retrieve global information like sd_journal_stream_fd(3) and
       sd_journal_get_catalog_for_message_id(3) — are fully thread-safe and may be called from multiple threads
       in parallel.

OPTIONAL DEPENDENCIES

       Depending on which build-time options are enabled, functions that operate on sd_journal objects might
       cause optional shared libraries to be dynamically loaded via dlopen(3), such as decompression libraries
       (xz, lz4, zstd) or cryptographic libraries (gcrypt).

NOTES

       Functions described here are available as a shared library, which can be compiled against and linked to
       with the libsystemd pkg-config(1) file.

       The code described here uses getenv(3), which is declared to be not multi-thread-safe. This means that
       the code calling the functions described here must not call setenv(3) from a parallel thread. It is
       recommended to only do calls to setenv() from an early phase of the program when no other threads have
       been started.

SEE ALSO

       systemd(1), sd_journal_print(3), sd_journal_stream_fd(3), sd_journal_open(3), sd_journal_next(3),
       sd_journal_get_data(3), sd_journal_get_realtime_usec(3), sd_journal_add_match(3),
       sd_journal_seek_head(3), sd_journal_enumerate_fields(3), sd_journal_get_cursor(3),
       sd_journal_get_cutoff_realtime_usec(3), sd_journal_get_cutoff_monotonic_usec(3), sd_journal_get_usage(3),
       sd_journal_get_fd(3), sd_journal_query_unique(3), sd_journal_get_catalog(3),
       sd_journal_has_runtime_files(3), sd_journal_has_persistent_files(3), journalctl(1), sd-id128(3), pkg-
       config(1)