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@@ -76,6 +76,76 @@ The journald sendv call can also be accessed directly: The two examples should give the same results in the log. +Reading from the journal is often similar to using the `journalctl` utility. + +Show all entries since 20 minutes ago (`journalctl --since "20 minutes ago"`): + + from systemd import journal + from datetime import datetime, timedelta + j = journal.Reader() + j.seek_realtime(datetime.now() - timedelta(minutes=20)) + for entry in j: + print(entry['MESSAGE']) + +Show entries between two timestamps (`journalctl --since "50 minutes ago" --until "10 minutes ago"`): + + from systemd import journal + from datetime import datetime, timedelta + j = journal.Reader() + since = datetime.now() - timedelta(minutes=50) + until = datetime.now() - timedelta(minutes=10) + j.seek_realtime(since) + for entry in j: + if entry['__REALTIME_TIMESTAMP'] > until: + break + print(entry['MESSAGE']) + +Show explanations of log messages alongside entries (`journalctl -x`): + + from systemd import journal + j = journal.Reader() + for entry in j: + print("MESSAGE: ", entry['MESSAGE']) + try: + print("CATALOG: ", j.get_catalog()) + except: + pass + +Show entries by a specific executable (`journalctl /usr/bin/vim`): + + from systemd import journal + j = journal.Reader() + j.add_match('_EXE=/usr/bin/vim') + for entry in j: + print(entry['MESSAGE']) + + - Note: matches can be added from many different fields, for example entries from a specific process ID can be matched with the `_PID` field, and entries from a specific unit (ie. `journalctl -u systemd-udevd.service`) can be matched with `_SYSTEMD_UNIT`. See all fields available at the [systemd.journal-fields docs](https://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html). + +Show kernel ring buffer (`journalctl -k`): + + from systemd import journal + j = journal.Reader() + j.add_match('_TRANSPORT=kernel') + for entry in j: + print(entry['MESSAGE']) + +Read entries in reverse (`journalctl _EXE=/usr/bin/vim -r`): + + from systemd import journal + class ReverseReader(journal.Reader): + def __next__(self): + ans = self.get_previous() + if ans: + return ans + raise StopIteration() + + j = ReverseReader() + j.add_match('_EXE=/usr/bin/vim') + j.seek_tail() + for entry in j: + print(entry['MESSAGE']) + + Notes ----- |