sd_journal_get_catalog, sd_journal_get_catalog_for_message_id — Retrieve message catalog entry
#include <systemd/sd-journal.h>
| int sd_journal_get_catalog( | sd_journal *j, | 
| char **ret ); | 
| int sd_journal_get_catalog_for_message_id( | sd_id128_t id, | 
| char **ret ); | 
sd_journal_get_catalog() retrieves a
    message catalog entry for the current journal entry. This will
    look up an entry in the message catalog by using the
    "MESSAGE_ID=" field of the current journal entry.
    Before returning the entry all journal field names in the catalog
    entry text enclosed in "@" will be replaced by the respective
    field values of the current entry. If a field name referenced in
    the message catalog entry does not exist, in the current journal
    entry, the "@" will be removed, but the field name otherwise left
    untouched.
sd_journal_get_catalog_for_message_id()
    works similar to sd_journal_get_catalog() but
    the entry is looked up by the specified message ID (no open
    journal context is necessary for this), and no field substitution
    is performed.
For more information about the journal message catalog please refer to the Journal Message Catalogs documentation page.
sd_journal_get_catalog() and
    sd_journal_get_catalog_for_message_id()
    return 0 on success or a negative errno-style error code. If no
    matching message catalog entry is found, -ENOENT is
    returned.
On successful return, ret points to a
    new string, which must be freed with
    free(3).
    
Function sd_journal_get_catalog() is thread-agnostic and only
    a single specific thread may operate on a given object during its entire lifetime. It's safe to allocate multiple
    independent objects and use each from a specific thread in parallel. However, it's not safe to allocate such an
    object in one thread, and operate or free it from any other, even if locking is used to ensure these threads don't
    operate on it at the very same time.
Function sd_journal_get_catalog_for_message_id() is are thread-safe and may be called in
    parallel from multiple threads.
Functions described here are available as a shared
  library, which can be compiled against and linked to with the
  libsystemd pkg-config(1)
  file.
sd_journal_get_catalog() and
    sd_journal_get_catalog_for_message_id() were added in version 196.