NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON

SD_JOURNAL_OPEN(3)             sd_journal_open            SD_JOURNAL_OPEN(3)

NAME         top

       sd_journal_open, sd_journal_open_directory,
       sd_journal_open_directory_fd, sd_journal_open_files,
       sd_journal_open_files_fd, sd_journal_close, sd_journal,
       SD_JOURNAL_LOCAL_ONLY, SD_JOURNAL_RUNTIME_ONLY, SD_JOURNAL_SYSTEM,
       SD_JOURNAL_CURRENT_USER, SD_JOURNAL_OS_ROOT - Open the system journal
       for reading

SYNOPSIS         top

       #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_directory_fd(sd_journal **ret, int fd,
                                        int flags);

       int sd_journal_open_files(sd_journal **ret, const char **paths,
                                 int flags);

       int sd_journal_open_files_fd(sd_journal **ret, int fds[],
                                    unsigned n_fds, int flags);

       void sd_journal_close(sd_journal *j);

DESCRIPTION         top

       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. The flags parameters accepted by this
       call are SD_JOURNAL_OS_ROOT, SD_JOURNAL_SYSTEM, and
       SD_JOURNAL_CURRENT_USER. If SD_JOURNAL_OS_ROOT is specified, journal
       files are searched for below the usual /var/log/journal and
       /run/log/journal relative to the specified path, instead of directly
       beneath it. The other two flags limit which files are opened, the
       same as for sd_journal_open().

       sd_journal_open_directory_fd() is similar to
       sd_journal_open_directory(), but takes a file descriptor referencing
       a directory in the file system instead of an absolute file system
       path.

       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_files_fd() is similar to sd_journal_open_files() but
       takes an array of open file descriptors that must reference journal
       files, instead of an array of file system paths. Pass the array of
       file descriptors as second argument, and the number of array entries
       in the third. The flags parameter must be passed as 0.

       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.

RETURN VALUE         top

       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.

NOTES         top

       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.

SEE ALSO         top

       systemd(1), sd-journal(3), sd_journal_next(3),
       sd_journal_get_data(3), systemd-machined(8)

COLOPHON         top

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       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a bug
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systemd 231                                               SD_JOURNAL_OPEN(3)