journalctl

journalctl

systemd-journald에 의해 생성된 관련 정보를 질의할 때 사용하는 명령이다.

 

사용법

journalctl [옵션] [항목]

 

주요 옵션

옵션	설명
-l, --full	출력 가능한 모든 필드의 정보를 출력한다.
-r, --reverse	역순으로 출력해주는 옵션으로 가장 최근 정보부터 출력한다.
-p, --priority	syslog에 사용하는 로그 레벨을 지정하는 옵션이다. 로그 레벨명이나 숫자값을 적으면 되고, 지정한 레벨 이상의 정보를 출력한다.
--since	특정 날짜 이후의 정보만 출력한다.”YYYY-MM-DD hh:mm:ss” 형식으로 지정한다.
--until	특정 날짜까지의 정보만 출력한다.”YYYY-MM-DD hh:mm:ss” 형식으로 지정한다.
-b	마지막 부팅 후에 로그

 

예시)

journalctl

[root@rocky1 ~]# journalctl May 10 17:13:11 Linux.kevin.com kernel: Linux version 5.14.0-162.23.1.el9_1.x86> May 10 17:13:11 Linux.kevin.com kernel: The list of certified hardware and clou> May 10 17:13:11 Linux.kevin.com kernel: Command line: BOOT_IMAGE=(hd0,msdos1)/v> May 10 17:13:11 Linux.kevin.com kernel: x86/fpu: Supporting XSAVE feature 0x001> May 10 17:13:11 Linux.kevin.com kernel: x86/fpu: Supporting XSAVE feature 0x002> May 10 17:13:11 Linux.kevin.com kernel: x86/fpu: Supporting XSAVE feature 0x004> May 10 17:13:11 Linux.kevin.com kernel: x86/fpu: Supporting XSAVE feature 0x200> May 10 17:13:11 Linux.kevin.com kernel: x86/fpu: xstate_offset[2]:  576, xstate> May 10 17:13:11 Linux.kevin.com kernel: x86/fpu: xstate_offset[9]:  832, xstate> May 10 17:13:11 Linux.kevin.com kernel: x86/fpu: Enabled xstate features 0x207,> May 10 17:13:11 Linux.kevin.com kernel: signal: max sigframe size: 3376 May 10 17:13:11 Linux.kevin.com kernel: BIOS-provided physical RAM map:

 

journalctl -n 5 : 최근 다섯개만 출력

[root@rocky1 ~]# journalctl -n 5 May 10 17:49:14 rocky1 systemd[1]: sysstat-collect.service: Deactivated success> May 10 17:49:14 rocky1 systemd[1]: Finished system activity accounting tool. May 10 17:50:40 rocky1 systemd[1]: Starting system activity accounting tool... May 10 17:50:40 rocky1 systemd[1]: sysstat-collect.service: Deactivated success> May 10 17:50:40 rocky1 systemd[1]: Finished system activity accounting tool.

 

journalctl -f 

[root@rocky1 ~]# journalctl -f #실시간 모니터링 May 10 17:48:29 rocky1 systemd[1]: Finished system activity accounting tool. May 10 17:49:14 rocky1 systemd[1]: Starting system activity accounting tool... May 10 17:49:14 rocky1 systemd[1]: sysstat-collect.service: Deactivated successfully. May 10 17:49:14 rocky1 systemd[1]: Finished system activity accounting tool. May 10 17:50:40 rocky1 systemd[1]: Starting system activity accounting tool... May 10 17:50:40 rocky1 systemd[1]: sysstat-collect.service: Deactivated successfully. May 10 17:50:40 rocky1 systemd[1]: Finished system activity accounting tool. May 10 17:51:29 rocky1 systemd[1]: Starting system activity accounting tool... May 10 17:51:29 rocky1 systemd[1]: sysstat-collect.service: Deactivated successfully. May 10 17:51:29 rocky1 systemd[1]: Finished system activity accounting tool.

 

journalctl -p err : 우선순위가 err 이상인 로그만을 조회한다. (err이상의 로그는 없으므로 에러 로그만 출력된다.)

[root@rocky1 ~]# journalctl -p err May 10 17:13:14 rocky1 kernel: piix4_smbus 0000:00:07.3: SMBus Host Controller > May 10 17:13:15 rocky1 kernel: Bluetooth: hci0: unexpected cc 0x0c12 length: 2 > May 10 17:13:15 rocky1 kernel: Bluetooth: hci0: Opcode 0x c12 failed: -38 May 10 17:13:16 rocky1 alsactl[1017]: alsa-lib main.c:1541:(snd_use_case_mgr_op> May 10 17:13:27 rocky1 gdm-password][3232]: gkr-pam: unable to locate daemon co> May 10 17:13:28 rocky1 systemd[3243]: Failed to start Application launched by g> May 10 17:13:30 rocky1 systemd[3243]: Failed to start Application launched by g> May 10 17:13:30 rocky1 systemd[3243]: Failed to start Application launched by g> May 10 17:13:30 rocky1 systemd[3243]: Failed to start Application launched by g> May 10 17:13:30 rocky1 systemd[3243]: Failed to start Application launched by g>

 

journalctl -u sshd.service

[root@rocky1 ~]# journalctl -u sshd.service #systemctl status sshd -l 과 같은 환경을 보여준다. May 10 17:13:17 rocky1 systemd[1]: Starting OpenSSH server daemon... May 10 17:13:17 rocky1 sshd[1126]: Server listening on 0.0.0.0 port 22. May 10 17:13:17 rocky1 sshd[1126]: Server listening on :: port 22. May 10 17:13:17 rocky1 systemd[1]: Started OpenSSH server daemon. May 10 17:25:49 rocky1 sshd[1126]: Received signal 15; terminating. May 10 17:25:49 rocky1 systemd[1]: Stopping OpenSSH server daemon... May 10 17:25:49 rocky1 systemd[1]: sshd.service: Deactivated successfully. May 10 17:25:49 rocky1 systemd[1]: Stopped OpenSSH server daemon. -- Boot a596393401ad40ad858e2a50a9fb4dee -- May 10 17:26:05 rocky1 systemd[1]: Starting OpenSSH server daemon... May 10 17:26:05 rocky1 sshd[1131]: Server listening on 0.0.0.0 port 22. May 10 17:26:05 rocky1 sshd[1131]: Server listening on :: port 22. May 10 17:26:05 rocky1 systemd[1]: Started OpenSSH server daemon.

 

journalctl -b  

[root@rocky1 ~]# vi /etc/systemd/journald.conf # 저널을 저장을 하기위해 설정을 한다 —------------------------ [Journal] Storage=persistent —------------------------  # 설정 후 reboot [root@rocky1 ~]# journalctl --list-boots -1 de5385cdfe764b0fa1803e4540a2ccd4 Wed 2023-05-10 17:13:30 KST--Wed 2023-05-10 17:22:> # 이전 부팅 기록 0 8f90c88a42a741d6813068a42c04f461 Wed 2023-05-10 17:22:35 KST--Wed 2023-05-10 17:59:> [root@rocky1 ~]# journalctl -b -1 May 10 17:13:30 linux.infta2.com kernel: Linux version 5.14.0-162.6.1.el9_1.0.1.x86_6> May 10 17:13:30 linux.infta2.com kernel: The list of certified hardware and cloud ins> May 10 17:13:30 linux.infta2.com kernel: Command line: BOOT_IMAGE=(hd0,msdos1)/vmlinu> #너무 길어 생략 #이 명령은 부팅 세션 중에 발생한 시스템 문제를 해결하고 진단하는데 사용된다