linux命令之dmesg命令-ag真人游戏

  linux dmesg（英文全称：display message）命令用于显示开机信息。kernel 会将开机信息存储在 ring buffer 中。您若是开机时来不及查看信息，可利用 dmesg 来查看。开机信息亦保存在 /var/log 目录中，名称为 dmesg 的文件里。

1、查看命令版本

(base) [root@s186 ~]# dmesg -v
dmesg，来自 util-linux 2.23.2

2、获取命令帮助

(base) [root@s186 ~]# dmesg -help
用法：
dmesg [选项]

选项：
-c, --clear 清除内核环形缓冲区(ring butter)
-c, --read-clear 读取并清除所有消息
-d, --console-off 禁止向终端打印消息
-d, --show-delta 显示打印消息之间的时间差
-e, --reltime 以易读格式显示本地时间和时间差
…

3、查看所有开机日志信息

(base) [root@s186 ~]# dmesg
[ 0.000000] microcode: microcode updated early to revision 0x25, date = 2018-04-02
[ 0.000000] initializing cgroup subsys cpuset
[ 0.000000] initializing cgroup subsys cpu
[ 0.000000] initializing cgroup subsys cpuacct
[ 0.000000] linux version 3.10.0-957.5.1.el7.x86_64 ([email protected]) (gcc version 4.8.5 20150623 (red hat 4.8.5-36) (gcc) ) #1
smp fri feb 1 14:54:57 utc 2019
[ 0.000000] command line: boot_image=/vmlinuz-3.10.0-957.5.1.el7.x86_64 root=uuid=062b2cf4-b789-4eb4-bc1a-4b48d8266d16 ro crashkernel=auto biosdev
name=0 rhgb quiet lang=en_us.utf-8
[ 0.000000] e820: bios-provided physical ram map:
[ 0.000000] bios-e820: [mem 0x0000000000000000-0x000000000009d7ff] usable
…

4、过滤想查看信息

#建议使用-i参数过滤时忽略大小写
(base) [root@s186 ~]# dmesg |grep -i cpu
[ 0.000000] initializing cgroup subsys cpuset
[ 0.000000] initializing cgroup subsys cpu
[ 0.000000] initializing cgroup subsys cpuacct
[ 0.000000] acpi: ssdt 00000000d8ffa810 00539 (v01 pmref cpu0ist 00003000 intl 20120711)
[ 0.000000] acpi: ssdt 00000000d8ffad50 00ad8 (v01 pmref cpupm 00003000 intl 20120711)
[ 0.000000] smpboot: allowing 4 cpus, 0 hotplug cpus
[ 0.000000] setup_percpu: nr_cpus:5120 nr_cpumask_bits:4 nr_cpu_ids:4 nr_node_ids:1
[ 0.000000] percpu: embedded 38 pages/cpu @ffff99c25fa00000 s118784 r8192 d28672 u524288
[ 0.000000] pcpu-alloc: s118784 r8192 d28672 u524288 alloc=1*2097152
[ 0.000000] pcpu-alloc: [0] 0 1 2 3
[ 0.000000] slub: hwalign=64, order=0-3, minobjects=0, cpus=4, nodes=1
[ 0.000000] rcu restricting cpus from nr_cpus=5120 to nr_cpu_ids=4.
[ 0.002975] mce: cpu supports 7 mce banks
[ 0.002981] cpu0: thermal monitoring enabled (tm1)
[ 0.039076] smpboot: cpu0: intel® core™ i3-4130 cpu @ 3.40ghz (fam: 06, model: 3c, stepping: 03)
[ 0.042323] nmi watchdog: enabled on all cpus, permanently consumes one hw-pmu counter.
[ 0.044633] brought up 4 cpus
[ 0.070551] acpi: ssdt ffff99c25fc62400 003d3 (v01 pmref cpu0cst 00003001 intl 20120711)
[ 0.341801] acpi: requesting acpi_cpufreq
[ 0.369369] cpuidle: using governor menu
[ 7.501018] cryptd: max_cpu_qlen set to 1000

5、便于阅读的方式显示日志日期和时间

(base) [root@s186 ~]# dmesg -d -t |grep -i memory
[二 10月 5 13:21:05 2021 < 0.000000>] base memory trampoline at [ffff99c040097000] 97000 size 24576
[二 10月 5 13:21:05 2021 < 0.000000>] reserving 161mb of memory at 688mb for crashkernel (system ram: 8110mb)
[二 10月 5 13:21:05 2021 < 0.000000>] early memory node ranges
[二 10月 5 13:21:05 2021 < 0.000000>] reserving intel graphics memory at [mem 0xdd200000-0xdf1fffff]
[二 10月 5 13:21:05 2021 < 0.000000>] pm: registered nosave memory: [mem 0x0009d000-0x0009dfff]
[二 10月 5 13:21:05 2021 < 0.000000>] pm: registered nosave
…

6、实时监控查看日志末尾n行

#实时查看日志末尾10行
(base) [root@s186 ~]# watch “dmesg | tail -10”

7、查看指定级别格式日志

(base) [root@s186 ~]# dmesg -l warn
[ 0.000000] acpi: rsdp 00000000000f0490 00024 (v02 dell )
[ 0.000000] acpi: xsdt 00000000d8fee080 00084 (v01 dell cbx3 01072009 ami 00010013)
[ 0.000000] acpi: facp 00000000d8ffa468 0010c (v05 dell cbx3 01072009 ami 00010013)
[ 0.000000] acpi: dsdt 00000000d8fee198 0c2ca (v02 dell cbx3 00000014 intl 20091112)
[ 0.000000] acpi: facs 00000000da7fe080 00040
#支持的日志级别(优先级)：
emerg - 系统无法使用
alert - 操作必须立即执行
crit - 紧急条件
err - 错误条件
warn - 警告条件
notice - 正常但重要的条件
info - 信息
debug - 调试级别的消息

8、打印并清除内核环形缓冲区

(base) [root@s186 ~]# dmesg-c
…
(base) [root@s186 ~]# dmesg |more
(base) [root@s186 ~]#

9、直接查看dmesg日志信息

(base) [root@s186 log]# cat /var/log/dmesg |more
[ 0.000000] microcode: microcode updated early to revision 0x25, date = 2018-04-02
[ 0.000000] initializing cgroup subsys cpuset
[ 0.000000] initializing cgroup subsys cpu
[ 0.000000] initializing cgroup subsys cpuacct
[ 0.000000] linux version 3.10.0-957.5.1.el7.x86_64 ([email protected]) (gcc version 4.8.5 20150623 (red hat 4.8.5-36) (gcc) ) #1
smp fri feb 1 14:54:57 utc 2019
[ 0.000000] command line: boot_image=/vmlinuz-3.10.0-957.5.1.el7.x86_64 root=uuid=062b2cf4-b789-4eb4-bc1a-4b48d8266d16 ro crashkernel=auto biosdev
name=0 rhgb quiet lang=en_us.utf-8

1、使用语法

#dmesg [选项]

2、参数说明