dmesg命令详解

基础命令学习目录

http://linux.cn/article-3587-1.html

dmesg 命令的使用范例

下面我们展示一些最负盛名的‘dmesg’命令工具以及其实际使用举例。‘dmesg’命令的使用语法如下。

• 1. 列出加载到内核中的所有驱动

  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@tecmintcom dmesg more
• root@tecmintcom dmesg less

• 1. ]Initializing ]Initializing ]Initializing ]Linux3.11013generic()(4.81(/ .-))#20-Ubuntu SMP Wed Oct 23 17:26:33 UTC 2013
  2. Ubuntu3.11013.20generic3.116 ]:
  3. ]IntelGenuineIntel
  4. ]AuthenticAMD
  5. ]Geodeby ]CyrixCyrixInstead
  6. ]CentaurCentaurHauls
  7. ]TransmetaGenuineTMx86
  8. ]TransmetaTransmetaCPU
  9. ] ]:-:
  10. ]-:[0x00000000000000000x000000000009fbff usable
  11. ]-:[0x00000000000f00000x00000000000fffff reserved
  12. ]-:[0x00000000001000000x000000007dc08bff usable
  13. ]-:[0x000000007dc08c000x000000007dc5cbff ACPI NVS
  14. ]-:[0x000000007dc5cc000x000000007dc5ebff ACPI data
  15. ]-:[0x000000007dc5ec000x000000007fffffff reserved
  16. ]-:[0x00000000e00000000x00000000efffffff reserved
  17. ]-:[0x00000000fec000000x00000000fed003ff reserved
  18. ]-:[0x00000000fed200000x00000000fed9ffff reserved
  19. ]-:[0x00000000fee000000x00000000feefffff reserved
  20. ]-:[0x00000000ffb000000x00000000ffffffff reserved
  21. ]( ):2. 列出所有被检测到的硬件
  1. root@tecmintcom dmesg grep sda
  2. ]2000 sda - logical blocks 250/ )
  3. ]2000 sda off
  4. ]2000 sda :003a0000
  5. ]2000 sda cache enabled read cache enabled doesn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。

     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。

  6. root@tecmintcom dmesg head 20
  7. ]Initializing ]Initializing ]Initializing ]Linux3.11013generic()(4.81(/ .-))#20-Ubuntu SMP Wed Oct 23 17:26:33 UTC 2013 (Ubuntu 3.11.0-13.20-generic 3.11.6)
  8. ]:
  9. ]IntelGenuineIntel
  10. ]AuthenticAMD
  11. ]Geodeby ]CyrixCyrixInstead
  12. ]CentaurCentaurHauls
  13. ]TransmetaGenuineTMx86
  14. ]TransmetaTransmetaCPU
  15. ] ]:-:
  16. ]-:[0x00000000000000000x000000000009fbff usable
  17. ]-:[0x00000000000f00000x00000000000fffff reserved
  18. ]-:[0x00000000001000000x000000007dc08bff usable
  19. ]-:[0x000000007dc08c000x000000007dc5cbff ACPI NVS
  20. ]-:[0x000000007dc5cc000x000000007dc5ebff ACPI data
  21. ]-:[0x000000007dc5ec000x000000007fffffff reserved

在‘dmesg’命令后跟随‘tail’命令（‘ dmesg | tail -20’）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@tecmintcom dmesg tail 20
• :-0x378 irq PCSPPTRISTATE:--():with swap on devsda2 :- extents1:--::()20002006NetfilterCoreTeam
• 0.50( buckets max:Registered10
• :DisabledPrivacyExtensions
• :LinkisUp1000MbpsFullDuplex :None
• work thread pool up
• work thread pool -:Loaded
• :Loaded
• :Security:-:noIPv6= audit1398268784.59318630 audit_enabled0= auid4294967295= res1
• -:-:-:5. 搜索包含特定字符串的被检测到的硬件

1. root@tecmintcom log dmesg grep i usb
2. root@tecmintcom log dmesg grep i dma
3. root@tecmintcom log dmesg grep i tty
4. root@tecmintcom log dmesg grep i memory

1. ]Scanning1for ]:[0x000000000x01ffffff ]Base[]9b00016384
2. ]:[0x000000000x000fffff ]:[0x378000000x379fffff ]:[0x340000000x377fffff ]:[0x001000000x33ffffff ]:[0x37a000000x37bfdfff ]Early ]:Registered:[0x0009f0000x000effff ]:Registered:[0x000f00000x000fffff ]try'cgroup_disable=memory'if't want memory cgroups
3. 6. 清空dmesg缓冲区日志

1. root@tecmintcom log dmesg c

在某些发行版中可以使用命令‘tail -f /var/log/dmesg’来实时监控dmesg的日志输出。

• root@tecmintcom log watch 结论：dmesg命令在系统dmesg记录实时更改或产生的情况下是非常有用的。你可以使用man dmesg来获取更多关于dmesg的信息。