sd-journal

systemd
Developer Lennart Poettering lennart@poettering.net
sd-journal 3
sd-journal APIs for submitting and querying log entries to and from the journal

    #include <systemd/sd-journal.h>

`pkg-config --cflags --libs libsystemd`

## Description

`sd-journal.h` 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 the sd_journal object are thread agnostic — given sd_journal pointer may only be used from one thread at a time, but multiple threads may use multiple such 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 thread-safe and may be called from multiple threads in parallel.

## 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