sd_journal_get_usage - Journal disk usage
int sd_journal_get_usage(sd_journal *j,
determines the total disk space currently used by
journal files (in bytes). If SD_JOURNAL_LOCAL_ONLY
was passed when
opening the journal, this value will only reflect the size of journal files of
the local host, otherwise of all hosts.
returns 0 on success or a negative errno-style
All functions listed here are 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.
These APIs are implemented as a shared library, which can be compiled and linked
to with the libsystemd pkg-config