sd_journal_open, sd_journal_open_directory, sd_journal_open_files, sd_journal_open_container, sd_journal_close, sd_journal, SD_JOURNAL_LOCAL_ONLY, SD_JOURNAL_RUNTIME_ONLY, SD_JOURNAL_SYSTEM, SD_JOURNAL_CURRENT_USER — Open the system journal for reading
#include <systemd/sd-journal.h>
int sd_journal_open( | sd_journal **ret, |
int flags) ; |
int sd_journal_open_directory( | sd_journal **ret, |
const char *path, | |
int flags) ; |
int sd_journal_open_files( | sd_journal **ret, |
const char **paths, | |
int flags) ; |
int sd_journal_open_container( | sd_journal **ret, |
const char *machine, | |
int flags) ; |
void sd_journal_close( | sd_journal *j) ; |
sd_journal_open()
opens
the log journal for reading. It will find all journal
files automatically and interleave them automatically
when reading. As first argument it takes a pointer to
a sd_journal
pointer, which on
success will contain a journal context object. The
second argument is a flags field, which may consist of
the following flags ORed together:
SD_JOURNAL_LOCAL_ONLY
makes sure
only journal files generated on the local machine will
be opened. SD_JOURNAL_RUNTIME_ONLY
makes sure only volatile journal files will be opened,
excluding those which are stored on persistent
storage. SD_JOURNAL_SYSTEM
will cause journal files of system services and the
kernel (in opposition to user session processes) to
be opened. SD_JOURNAL_CURRENT_USER
will cause journal files of the current user to be
opened. If neither SD_JOURNAL_SYSTEM
nor SD_JOURNAL_CURRENT_USER
are
specified, all journal file types will be opened.
sd_journal_open_directory()
is similar to sd_journal_open()
but takes an absolute directory path as argument. All
journal files in this directory will be opened and
interleaved automatically. This call also takes a
flags argument, but it must be passed as 0 as no flags
are currently understood for this call.
sd_journal_open_files()
is similar to sd_journal_open()
but takes a NULL
-terminated list
of file paths to open. All files will be opened and
interleaved automatically. This call also takes a
flags argument, but it must be passed as 0 as no flags
are currently understood for this call. Please note
that in the case of a live journal, this function is only
useful for debugging, because individual journal files
can be rotated at any moment, and the opening of
specific files is inherently racy.
sd_journal_open_container()
is similar to sd_journal_open()
but opens the journal files of a running
OS container. The specified machine name refers to a
container that is registered with
systemd-machined(8).
sd_journal
objects cannot be
used in the child after a fork. Functions which take a
journal object as an argument
(sd_journal_next()
and others)
will return -ECHILD
after a fork.
sd_journal_close()
will
close the journal context allocated with
sd_journal_open()
or
sd_journal_open_directory()
and
free its resources.
When opening the journal only journal files accessible to the calling user will be opened. If journal files are not accessible to the caller, this will be silently ignored.
See
sd_journal_next(3)
for an example of how to iterate through the journal
after opening it with
sd_journal_open()
.
A journal context object returned by
sd_journal_open()
references a
specific journal entry as current entry,
similar to a file seek index in a classic file system
file, but without absolute positions. It may be
altered with
sd_journal_next(3)
and
sd_journal_seek_head(3)
and related calls. The current entry position may be
exported in cursor strings, as accessible
via
sd_journal_get_cursor(3). Cursor
strings may be used to globally identify a specific
journal entry in a stable way and then later to seek
to it (or if the specific entry is not available
locally, to its closest entry in time)
sd_journal_seek_cursor(3).
Notification of journal changes is available via
sd_journal_get_fd()
and related
calls.
The sd_journal_open()
,
sd_journal_open_directory()
, and
sd_journal_open_files()
calls
return 0 on success or a negative errno-style error
code. sd_journal_close()
returns
nothing.
The sd_journal_open()
,
sd_journal_open_directory()
and
sd_journal_close()
interfaces are
available as a shared library, which can be compiled and
linked to with the
libsystemd
pkg-config(1)
file.
sd_journal_open()
,
sd_journal_close()
,
SD_JOURNAL_LOCAL_ONLY
,
SD_JOURNAL_RUNTIME_ONLY
,
SD_JOURNAL_SYSTEM_ONLY
were added
in systemd-38.
sd_journal_open_directory()
was added in systemd-187.
SD_JOURNAL_SYSTEM
,
SD_JOURNAL_CURRENT_USER
,
and sd_journal_open_files()
were added in systemd-205.
SD_JOURNAL_SYSTEM_ONLY
was deprecated.