370c7da4a9
nixpkgs nixos-25.11 브랜치의 nixos/doc/manual/ 디렉토리를 sparse clone으로 가져와 ~/obsidian/dev/nixos-manual/에 복사. _index.md에 구조/갱신 방법 정리. 오프라인 참조 + AI 에이전트 컨텍스트용. sandbox-tokyo 같은 NixOS 노드 운영 시 빠른 참조로 사용.
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Logging
System-wide logging is provided by systemd's journal, which subsumes
traditional logging daemons such as syslogd and klogd. Log entries are
kept in binary files in /var/log/journal/. The command journalctl
allows you to see the contents of the journal. For example,
$ journalctl -b
shows all journal entries since the last reboot. (The output of
journalctl is piped into less by default.) You can use various
options and match operators to restrict output to messages of interest.
For instance, to get all messages from PostgreSQL:
$ journalctl -u postgresql.service
-- Logs begin at Mon, 2013-01-07 13:28:01 CET, end at Tue, 2013-01-08 01:09:57 CET. --
...
Jan 07 15:44:14 hagbard postgres[2681]: [2-1] LOG: database system is shut down
-- Reboot --
Jan 07 15:45:10 hagbard postgres[2532]: [1-1] LOG: database system was shut down at 2013-01-07 15:44:14 CET
Jan 07 15:45:13 hagbard postgres[2500]: [1-1] LOG: database system is ready to accept connections
Or to get all messages since the last reboot that have at least a "critical" severity level:
$ journalctl -b -p crit
Dec 17 21:08:06 mandark sudo[3673]: pam_unix(sudo:auth): auth could not identify password for [alice]
Dec 29 01:30:22 mandark kernel[6131]: [1053513.909444] CPU6: Core temperature above threshold, cpu clock throttled (total events = 1)
The system journal is readable by root and by users in the wheel and
systemd-journal groups. All users have a private journal that can be
read using journalctl.