dmesg命令

列出加载到内核中的所有驱动

[root@node01 ~]# dmesg | more
[    0.000000] Initializing cgroup subsys cpuset
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Initializing cgroup subsys cpuacct
。。。。。。。。。。。。。。。。。。。。。

列出所有被检测到的硬件

[root@node01 ~]#  dmesg | grep sda
[    1.070628] sd 0:0:0:0: [sda] 41943040 512-byte logical blocks: (21.4 GB/20.0 GiB)
[    1.070670] sd 0:0:0:0: [sda] Write Protect is off
[    1.070673] sd 0:0:0:0: [sda] Mode Sense: 61 00 00 00
[    1.070716] sd 0:0:0:0: [sda] Cache data unavailable
[    1.070719] sd 0:0:0:0: [sda] Assuming drive cache: write through
[    1.083734]  sda: sda1 sda2
[    1.084105] sd 0:0:0:0: [sda] Attached SCSI disk
[   29.714922] XFS (sda1): Mounting V5 Filesystem
[   46.608484] XFS (sda1): Ending clean mount

只输出dmesg命令的前20行日志

[root@node01 ~]# dmesg | head -20
[    0.000000] Initializing cgroup subsys cpuset
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Initializing cgroup subsys cpuacct
[    0.000000] Linux version 3.10.0-693.el7.x86_64 (builder@kbuilder.dev.centos.org) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) ) #1 SMP Tue Aug 22 21:09:27 UTC 2017
[    0.000000] Command line: BOOT_IMAGE=/vmlinuz-3.10.0-693.el7.x86_64 root=/dev/mapper/centos-root ro crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet LANG=zh_CN.UTF-8
[    0.000000] Disabled fast string operations
[    0.000000] e820: BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009ebff] usable
[    0.000000] BIOS-e820: [mem 0x000000000009ec00-0x000000000009ffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000000dc000-0x00000000000fffff] reserved
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000001fedffff] usable
[    0.000000] BIOS-e820: [mem 0x000000001fee0000-0x000000001fefefff] ACPI data
[    0.000000] BIOS-e820: [mem 0x000000001feff000-0x000000001fefffff] ACPI NVS
[    0.000000] BIOS-e820: [mem 0x000000001ff00000-0x000000001fffffff] usable
[    0.000000] BIOS-e820: [mem 0x00000000f0000000-0x00000000f7ffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fec0ffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000fee00fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fffe0000-0x00000000ffffffff] reserved
[    0.000000] NX (Execute Disable) protection: active
[    0.000000] SMBIOS 2.7 present.

搜索包含特定字符串的被检测到的硬件

dmesg | grep -i usb
dmesg | grep -i dma
dmesg | grep -i tty
dmesg | grep -i memory

清空dmesg缓冲区日志

[root@node01 ~]# dmesg -c

实时监控dmesg日志输出

[root@node01 ~]# tail -f /var/log/dmesg
[   26.476228] floppy0: no floppy controllers found
[   26.476292] work still pending
[   26.917993] ppdev: user-space parallel port driver
[   27.688404] AES CTR mode by8 optimization enabled
[   27.690744] alg: No test for __gcm-aes-aesni (__driver-gcm-aes-aesni)
[   27.876144] alg: No test for crc32 (crc32-pclmul)
[   27.922238] Adding 1023996k swap on /dev/mapper/centos-swap.  Priority:-1 extents:1 across:1023996k FS
[   29.714922] XFS (sda1): Mounting V5 Filesystem
[   46.608484] XFS (sda1): Ending clean mount
[   47.241588] type=1305 audit(1580699963.196:3): audit_pid=636 old=0 auid=4294967295 ses=4294967295 res=1