dmesg 可以查看linux 内核信息

dmesg’命令设备故障的诊断是非常重要的。在‘dmesg’命令的帮助下进行硬件的连接或断开连接操作时，我们可以看到硬件的检测或者断开连接的信息。‘dmesg’命令在多数基于Linux和Unix的操作系统中都可以使用。

1. 列出加载到内核中的所有驱动

我们可以使用如‘more’。 ‘tail’, ‘less ’或者‘grep’文字处理工具来处理‘dmesg’命令的输出。由于dmesg日志的输出不适合在一页中完全显示，因此我们使用管道（pipe）将其输出送到more或者less命令单页显示。

root@cdncenter ~]# dmesg |more

[    0.000000] Initializing cgroup subsys cpuset

[    0.000000] Initializing cgroup subsys cpu

[    0.000000] Initializing cgroup subsys cpuacct

[    0.000000] Linux version 3.10.-693.2..el7.x86_64 (builder@kbuilder.dev.centos.org) (gcc version 4.8.

 (Red Hat 4.8.-) (GCC) ) # SMP Tue Sep  :: UTC

[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-3.10.-693.2..el7.x86_64 root=UUID=eb448abb--4d8d-bcde-

434d586a31 ro crashkernel=auto net.ifnames= console=tty0 console=ttyS0,115200n8

[    0.000000] e820: BIOS-provided physical RAM map:

[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable

[    0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved

[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000bffdffff] usable

[    0.000000] BIOS-e820: [mem 0x00000000bffe0000-0x00000000bfffffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved

[    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000043fffffff] usable

[    0.000000] NX (Execute Disable) protection: active

[    0.000000] SMBIOS 2.8 present.

[    0.000000] DMI: Alibaba Cloud Alibaba Cloud ECS, BIOS rel-1.7.--ge51488c-20140602_164612-nilsson.home.kraxel.org //

[    0.000000] Hypervisor detected: KVM

[    0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved

[    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable

[    0.000000] e820: last_pfn = 0x440000 max_arch_pfn = 0x400000000

[    0.000000] MTRR default type: write-back

[    0.000000] MTRR fixed ranges enabled:

[    0.000000]   -9FFFF write-back

[    0.000000]   A0000-BFFFF uncachable

[    0.000000]   C0000-FFFFF write-protect

[    0.000000] MTRR variable ranges enabled:

[    0.000000]    base 0000C0000000 mask 3FFFC0000000 uncachable

[    0.000000]    disabled

[    0.000000]    disabled

[    0.000000]    disabled

[    0.000000]    disabled

[    0.000000]    disabled

[    0.000000]    disabled

[    0.000000]    disabled

[    0.000000] x86 PAT enabled: cpu , old 0x7040600070406, new 0x7010600070106

[    0.000000] e820: last_pfn = 0xbffe0 max_arch_pfn = 0x400000000

[    0.000000] found SMP MP-table at [mem 0x000f0e80-0x000f0e8f] mapped at [ffff8800000f0e80]

[    0.000000] Base memory trampoline at [ffff880000099000]  size

[    0.000000] Using GB pages for direct mapping

[    0.000000] BRK [0x01fe9000, 0x01fe9fff] PGTABLE

[    0.000000] BRK [0x01fea000, 0x01feafff] PGTABLE

[    0.000000] BRK [0x01feb000, 0x01febfff] PGTABLE

[    0.000000] RAMDISK: [mem 0x35e41000-0x36f18fff]

--More--
dmesg | less

2. 列出所有被检测到的硬件

要显示所有被内核检测到的硬盘设备，你可以使用‘grep’命令搜索‘sda’关键词，如下

dmesg |grep sda

sd :::: [sda]  -byte logical blocks: ( GB/ GiB)

sd :::: [sda] Write Protect is off

sd :::: [sda] Mode Sense:

sd :::: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA

 sda: sda1 sda2 sda3 sda4 < sda5 sda6 sda7 sda8 >

sd :::: [sda] Attached SCSI disk

EXT4-fs (sda5): INFO: recovery required on readonly filesystem

EXT4-fs (sda5): write access will be enabled during recovery

EXT4-fs (sda5): orphan cleanup on readonly fs

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5): ext4_orphan_cleanup: deleting unreferenced inode

EXT4-fs (sda5):  orphan inodes deleted

EXT4-fs (sda5): recovery complete

EXT4-fs (sda5): mounted filesystem with ordered data mode. Opts:

dracut: Mounted root filesystem /dev/sda5

EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts:

EXT4-fs (sda8): mounted filesystem with ordered data mode. Opts:

EXT4-fs (sda6): mounted filesystem with ordered data mode. Opts:

EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts:

EXT4-fs (sda3): mounted filesystem with ordered data mode. Opts:

Adding 4095992k swap on /dev/sda7.  Priority:- extents: across:4095992k

注解 ‘sda’表示第一块 SATA硬盘，‘sdb’表示第二块SATA硬盘。若想查看IDE硬盘搜索‘hda’或‘hdb’关键词。

3. 只输出dmesg命令的前20行日志

在‘dmesg’命令后跟随‘head’命令来显示开始几行，‘dmesg | head -20′命令将显示开始的前20行

[root@cdncenter ~]# dmesg |head -

[    0.000000] Initializing cgroup subsys cpuset

[    0.000000] Initializing cgroup subsys cpu

[    0.000000] Initializing cgroup subsys cpuacct

[    0.000000] Linux version 3.10.-693.2..el7.x86_64 (builder@kbuilder.dev.centos.org) (gcc version 4.8.  (Red Hat 4.8.-) (GCC) ) # SMP Tue Sep  :: UTC

[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-3.10.-693.2..el7.x86_64 root=UUID=eb448abb--4d8d-bcde-94434d586a31 ro crashkernel=auto net.ifnames= console=tty0 console=ttyS0,115200n8

[    0.000000] e820: BIOS-provided physical RAM map:

[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable

[    0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved

[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000bffdffff] usable

[    0.000000] BIOS-e820: [mem 0x00000000bffe0000-0x00000000bfffffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved

[    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000043fffffff] usable

[    0.000000] NX (Execute Disable) protection: active

[    0.000000] SMBIOS 2.8 present.

[    0.000000] DMI: Alibaba Cloud Alibaba Cloud ECS, BIOS rel-1.7.--ge51488c-20140602_164612-nilsson.home.kraxel.org //

[    0.000000] Hypervisor detected: KVM

[    0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved

[    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable

4. 只输出dmesg命令最后20行日志

在‘dmesg’命令后跟随‘tail’命令（‘ dmesg | tail -fn20’）来输出‘dmesg’命令的最后20行日志，当你插入可移动设备时它是非常有用的。

[root@cdncenter ~]# dmesg |tail -fn

[    2.314442] systemd[]: RTC configured in localtime, applying delta of  minutes to system time.

[    2.356464] ip_tables: (C) - Netfilter Core Team

[    2.357910] systemd[]: Inserted module 'ip_tables'

[    2.738351] EXT4-fs (vda1): re-mounted. Opts: (null)

[    2.764522] systemd-journald[]: Received request to flush runtime journal from PID

[    2.959266] piix4_smbus ::01.3: SMBus Host Controller at 0x700, revision

[    2.961623] input: PC Speaker as /devices/platform/pcspkr/input/input5

[    2.997176] ppdev: user-space parallel port driver

[    3.042041] AES CTR mode by8 optimization enabled

[    3.046874] alg: No test for __gcm-aes-aesni (__driver-gcm-aes-aesni)

[    3.055487] alg: No test for crc32 (crc32-pclmul)

[    3.067561] EDAC MC: Ver: 3.0.

[    3.099789] type= audit(1532936276.320:): audit_pid= old= auid= ses= res=

[   25.780005] random: crng init done

[  143.596270]  vdb: vdb1

[  235.262057] EXT4-fs (vdb1): mounting ext3 file system using the ext4 subsystem

[  235.266667] EXT4-fs (vdb1): mounted filesystem with ordered data mode. Opts: (null)

[ 7739.681829] nf_conntrack version 0.5. ( buckets,  max)

[ 7796.760635] ip_tables: (C) - Netfilter Core Team

[ 7796.772093] nf_conntrack version 0.5. ( buckets,  max)

由于‘dmesg’命令的输出实在太长了，在其中搜索某个特定的字符串是非常困难的。因此，有必要过滤出一些包含‘usb’ ‘dma’ ‘tty’ ‘memory’等字符串的日志行。grep 命令 的‘-i’选项表示忽略大小写

[root@cdncenter ~]# dmesg | grep -i memory

[    0.000000] Base memory trampoline at [ffff880000099000]  size

[    0.000000] Reserving 161MB of memory at 688MB for crashkernel (System RAM: 16383MB)

[    0.000000] Early memory node ranges

[    0.000000] PM: Registered nosave memory: [mem 0x0009f000-0x0009ffff]

[    0.000000] PM: Registered nosave memory: [mem 0x000a0000-0x000effff]

[    0.000000] PM: Registered nosave memory: [mem 0x000f0000-0x000fffff]

[    0.000000] PM: Registered nosave memory: [mem 0xbffe0000-0xbfffffff]

[    0.000000] PM: Registered nosave memory: [mem 0xc0000000-0xfeffbfff]

[    0.000000] PM: Registered nosave memory: [mem 0xfeffc000-0xfeffffff]

[    0.000000] PM: Registered nosave memory: [mem 0xff000000-0xfffbffff]

[    0.000000] PM: Registered nosave memory: [mem 0xfffc0000-0xffffffff]

[    0.000000] Memory: 4978256k/17825792k available (6886k kernel code, 1049096k absent, 528008k reserved, 4545k data, 1764k init)

[    0.000000] please try 'cgroup_disable=memory' option if you don't want memory cgroups

[    0.438460] Initializing cgroup subsys memory

[    1.113298] Freeing initrd memory: 17248k freed

[    1.204199] Non-volatile memory driver v1.

[    1.206865] crash memory driver: version 1.1

[    1.308053] Freeing unused kernel memory: 1764k freed

[    1.614633] [TTM] Zone  kernel: Available graphics memory:  kiB

[    1.614633] [TTM] Zone   dma32: Available graphics memory:  kiB

7. 实时监控dmesg日志输出

[root@cdncenter ~]# tail -f /var/log/dmesg

[    2.738351] EXT4-fs (vda1): re-mounted. Opts: (null)

[    2.764522] systemd-journald[]: Received request to flush runtime journal from PID

[    2.959266] piix4_smbus ::01.3: SMBus Host Controller at 0x700, revision

[    2.961623] input: PC Speaker as /devices/platform/pcspkr/input/input5

[    2.997176] ppdev: user-space parallel port driver

[    3.042041] AES CTR mode by8 optimization enabled

[    3.046874] alg: No test for __gcm-aes-aesni (__driver-gcm-aes-aesni)

[    3.055487] alg: No test for crc32 (crc32-pclmul)

[    3.067561] EDAC MC: Ver: 3.0.

[    3.099789] type= audit(1532936276.320:): audit_pid= old= auid= ses= res=

查看存储在‘/var/log/dmesg’文件中的日志

查看dmesg中的时间

通过dmesg列出的事件时间不易理解，例如：

[19078.666869] EXT4-fs (sdl): warning: maximal mount count reached, running e2fsck is recommended

[19078.723154] EXT4-fs (sdm): warning: maximal mount count reached, running e2fsck is recommended

[19078.913409] EXT4-fs (sdh): warning: maximal mount count reached, running e2fsck is recommended

[69740.690129] Bridge firewalling registered

通过下面命令转换成可读时间：

[root@buffer236017 src]# date -d "1970-01-01 UTC `echo "$(date +%s)-$(cat /proc/uptime|cut -f  -d' ')+69740.690129"|bc `seconds"

Fri Aug  :: CST

[root@buffer236017 src]#

Linux dmesg输出没有时间列

网上查了半天，发现是系统自带的版本太低，dmesg命令不支时间参数，如果需要输出时间字段，需要重新编译内核，设置下面参数：CONFIG_PRINTK_TIME=y

还有一种变通的方法，利用rsyslog，将kernel日志输出到文件中，修改/etc/[r]syslog.conf，添加如下配置：
kern.*                                                  /var/log/kern.log

重启rsyslog守护进程即可，后续可以在 /var/log/kern.log中查看 kernel日志信息。

linux dmesg 查看系统故障信息的更多相关文章

  1. linux下查看串口信息

    rs232串口通信接口:当通信距离较近时(<12m),可以使用电缆线直接连接,若距离较远,需附加调制解调器. 9个脚针的定义: CDC数据载波检测,RXD接收数据,TXD发送数据,DTR数据中断 ...

  2. Linux下查看CPU信息、机器型号等硬件信息命令

    Linux下查看CPU信息.机器型号等硬件信息命令 编写一个bash脚本: vim info.sh #!/bin/bash cat /etc/issue echo "____________ ...

  3. Linux下 查看CPU信息

    参考: Linux和Windows下查看cpu和core个数 Linux下 查看CPU信息 1.查看完整CPU信息: $ cat /proc/cpuinfo 2.查看逻辑cpu个数: $ cat /p ...

  4. [转]Linux下查看CPU信息、机器型号等硬件信息

    From: http://www.jbxue.com/LINUXjishu/14582.html 查看CPU信息(型号) : # cat /proc/cpuinfo | grep name | cut ...

  5. Linux中查看CPU信息【转】

    [转自]:http://blog.chinaunix.net/uid-23622436-id-3311579.html cat /proc/cpuinfo中的信息 processor       逻辑 ...

  6. Linux中查看CPU信息 （转）

    cat /proc/cpuinfo中的信息 processor       逻辑处理器的id. physical id    物理封装的处理器的id. core id        每个核心的id. ...

  7. Linux下查看硬件信息的方法

    用硬件检测程序kuduz探测新硬件:service kudzu start ( or restart) 查看CPU信息:cat /proc/cpuinfo 查看板卡信息:cat /proc/pci 查 ...

  8. 如何在Linux下查看版本信息

    Linux下如何查看版本信息, 包括位数.版本信息以及CPU内核信息.CPU具体型号等等,整个CPU信息一目了然.   1.# uname -a   (Linux查看版本当前操作系统内核信息)   L ...

  9. Linux系统查看日志信息总结

    命令: cat tail -f #系统日志文件存放路径: /var/log/message #系统启动后的信息和错误日志 /var/log/secure #与安全相关的日志信息 /var/log/ma ...

随机推荐

  1. Mac 安装 Jenkins

    Mac 安装 Jenkins 有两种方法 方法一: 从官方下载最新版本:http://mirrors.jenkins-ci.org/osx/latest 点击安装. 方法二(推荐): 使用 homeb ...

  2. Java开发中Maven Jar包管理建议

    Jar包管理规范 基于使用Git做版本控制,使用Jenkins做持续集成,以及Git-flow分支管理策略的情况: 带-SNAPSHOT为快照版本,例如1.0.0-SNAPSHOT 正式发布版本只有版 ...

  3. cookie是如何保存到客户端，又是如何发送到服务端

    Cookie相关的Http头     有 两个Http头部和Cookie有关:Set-Cookie和Cookie.     Set-Cookie由服务器发送,它包含在响应请求的头部中.它用于在客户端创 ...

  4. [Laravel] 15 - REST API: sidebar with unit test

    前言 实现一个博客的侧边栏的链接,然后顺便对其进行单元测试的过程. Archives 一.视图中展示SQL结果 一条 sql 语句[查询] select year(created_at) year, ...

  5. [Android] 基于 Linux 命令行构建 Android 应用（三）：构建流程

    Android 应用的构建过程就是将 Android 项目中的文件和资源进行编译和打包,最后将结果输出到 .apk 文件..apk 文件是保存二进制文件的容器,它包含了运行安卓应用所需的所有信息,例如 ...

  6. sencha touch 在新版谷歌浏览器中painted事件无法触发解决方案以及carousel 控件、togglefield控件、滚动条失效

    在2.3/2.4版本中,新版谷歌浏览器(43.44版本)里面painted事件是不会触发的,以及carousel 控件.togglefield控件.滚动条失效,官方的解决方案如下,测试可用 会出现这个 ...

  7. sencha touch 百度地图扩展(2014-12-17)

    上个版本http://www.cnblogs.com/mlzs/p/3666466.html,新增了一些功能,修复了一些bug 扩展代码如下: Ext.define('ux.BMap', { alte ...

  8. go 的文件处理

    准备一个文件 imooc.txt hello world! 一.使用 io/ioutil 包 定义一个 check 函数 func check(err error) { if err != nil { ...

  9. ELK之从6.3.1升级至6.6.2

    需要把原6.3.1版本升级为6.6.2版本 1,官网下载rpm包 2,升级elasticsearch和kibana rpm -U elasticsearch-6.6.2.rpm rpm -U kiba ...

  10. PL-SVO

    pl-svo对第一帧提取点和线段特征,点特征直接保存为Point2f就行,对于线段特征保存线段的两个端点 void detectFeatures( FramePtr frame, vector< ...