---
author: ''
category: 技术
comments_data:
- date: '2014-08-11 18:33:01'
  message: 用不到
  postip: 198.143.130.90
  username: 微博评论
- date: '2014-08-11 20:03:01'
  message: 马克！
  postip: 60.29.248.94
  username: 微博评论
- date: '2014-08-13 15:33:01'
  message: dmesg
  postip: 113.108.131.227
  username: 微博评论
- date: '2014-08-13 20:33:02'
  message: 收下了
  postip: 110.90.30.149
  username: 微博评论
- date: '2015-09-14 15:58:28'
  message: "安装在pc上的Ubuntu运行一个段错误程序后，用dmesg可以打印出这个段错误的相关信息：<br />\r\n[695596.585044]
    xiao[19078]: segfault at 0 ip 080483c4 sp bf815788 error 6 in xiao[8048000+1000]<br
    />\r\n[710079.934715] a.out[14084]: segfault at 0 ip 080483c4 sp bff93648 error
    6 in a.out[8048000+1000]<br />\r\n[712629.489738] xiao[28812]: segfault at 0 ip
    080483c4 sp bf965978 error 6 in xiao[8048000+1000]<br />\r\n但我自己编了一个linux内核在ARM上面跑，相关的段错误信息不能用dmesg打印出来，请问这是需要安装什么服务、或是系统配置吗？请指教。"
  postip: 171.221.252.30
  username: zxc [Liebao|Windows 7]
- date: '2016-06-09 21:25:21'
  message: 在文中列出的情况下，没有必要用grep，直接在less中就可以。 &amp;pattern&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;
    &nbsp; *&nbsp;&nbsp;Display only matching lines.&nbsp;&nbsp;-- from help page
    of less
  postip: 114.212.81.249
  username: 来自江苏南京南京大学的 Firefox 46.0|Windows 10 用户
count:
  commentnum: 6
  favtimes: 3
  likes: 0
  sharetimes: 6
  viewnum: 78102
date: '2014-08-11 18:05:47'
editorchoice: false
excerpt: ‘dmesg’命令显示linux内核的环形缓冲区信息，我们可以从中获得诸如系统架构、cpu、挂载的硬件，RAM等多个运行级别的大量的系统信息。当计算机启动时，系统内核（操作系统的核心部分）将会被加载到内存中。在加载的过程中会显示很多的信息，在这些信息中我们可以看到内核检测硬件设备。
fromurl: http://www.tecmint.com/dmesg-commands/
id: 3587
islctt: true
largepic: /images/p/201408/11/180550vdreddxx16k13p2x.png
permalink: /article-3587-1.html
pic: /images/p/201408/11/180550vdreddxx16k13p2x.png.thumb.jpg
related: []
reviewer: ''
selector: ''
summary: ‘dmesg’命令显示linux内核的环形缓冲区信息，我们可以从中获得诸如系统架构、cpu、挂载的硬件，RAM等多个运行级别的大量的系统信息。当计算机启动时，系统内核（操作系统的核心部分）将会被加载到内存中。在加载的过程中会显示很多的信息，在这些信息中我们可以看到内核检测硬件设备。
tags:
- dmesg
- 命令
- Linux
thumb: false
title: Linux系统中‘dmesg’命令处理故障和收集系统信息的7种用法
titlepic: false
translator: cvsher
updated: '2014-08-11 18:05:47'
---

‘dmesg’命令显示linux内核的环形缓冲区信息，我们可以从中获得诸如系统架构、cpu、挂载的硬件，RAM等多个运行级别的大量的系统信息。当计算机启动时，系统内核（操作系统的核心部分）将会被加载到内存中。在加载的过程中会显示很多的信息，在这些信息中我们可以看到内核检测硬件设备。


[![dmesg Command Examples](https://camo.githubusercontent.com/433d31191ed6401b5285a33a5b0a6c01d439d0fe/687474703a2f2f7777772e7465636d696e742e636f6d2f77702d636f6e74656e742f75706c6f6164732f323031342f30372f646d6573672d436f6d6d616e642d4578616d706c65732e706e67)](https://camo.githubusercontent.com/433d31191ed6401b5285a33a5b0a6c01d439d0fe/687474703a2f2f7777772e7465636d696e742e636f6d2f77702d636f6e74656e742f75706c6f6164732f323031342f30372f646d6573672d436f6d6d616e642d4578616d706c65732e706e67)


dmesg 命令的使用范例


‘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。


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。



```
# dmesg [options...]

```

### 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@tecmint.com ~]# dmesg | more
[root@tecmint.com ~]# dmesg | less

```

### 输出



```
[    0.000000] Initializing cgroup subsys cpuset
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Initializing cgroup subsys cpuacct
[    0.000000] Linux version 3.11.0-13-generic (buildd@aatxe) (gcc version 4.8.1 (Ubuntu/Linaro 4.8.1-10ubuntu8) ) #20-Ubuntu SMP Wed Oct 23 17:26:33 UTC 2013 
(Ubuntu 3.11.0-13.20-generic 3.11.6)
[    0.000000] KERNEL supported cpus:
[    0.000000]   Intel GenuineIntel
[    0.000000]   AMD AuthenticAMD
[    0.000000]   NSC Geode by NSC
[    0.000000]   Cyrix CyrixInstead
[    0.000000]   Centaur CentaurHauls
[    0.000000]   Transmeta GenuineTMx86
[    0.000000]   Transmeta TransmetaCPU
[    0.000000]   UMC UMC UMC UMC
[    0.000000] e820: BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
[    0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000007dc08bff] usable
[    0.000000] BIOS-e820: [mem 0x000000007dc08c00-0x000000007dc5cbff] ACPI NVS
[    0.000000] BIOS-e820: [mem 0x000000007dc5cc00-0x000000007dc5ebff] ACPI data
[    0.000000] BIOS-e820: [mem 0x000000007dc5ec00-0x000000007fffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000e0000000-0x00000000efffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fed003ff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fed20000-0x00000000fed9ffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000feefffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000ffb00000-0x00000000ffffffff] reserved
[    0.000000] NX (Execute Disable) protection: active
.....

```

### 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：



```
[root@tecmint.com ~]# dmesg | grep sda

[    1.280971] sd 2:0:0:0: [sda] 488281250 512-byte logical blocks: (250 GB/232 GiB)
[    1.281014] sd 2:0:0:0: [sda] Write Protect is off
[    1.281016] sd 2:0:0:0: [sda] Mode Sense: 00 3a 00 00
[    1.281039] sd 2:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[    1.359585]  sda: sda1 sda2 < sda5 sda6 sda7 sda8 >
[    1.360052] sd 2:0:0:0: [sda] Attached SCSI disk
[    2.347887] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
[   22.928440] Adding 3905532k swap on /dev/sda6.  Priority:-1 extents:1 across:3905532k FS
[   23.950543] EXT4-fs (sda1): re-mounted. Opts: errors=remount-ro
[   24.134016] EXT4-fs (sda5): mounted filesystem with ordered data mode. Opts: (null)
[   24.330762] EXT4-fs (sda7): mounted filesystem with ordered data mode. Opts: (null)
[   24.561015] EXT4-fs (sda8): mounted filesystem with ordered data mode. Opts: (null)

```

**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@tecmint.com ~]# 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 3.11.0-13-generic (buildd@aatxe) (gcc version 4.8.1 (Ubuntu/Linaro 4.8.1-10ubuntu8) ) #20-Ubuntu SMP Wed Oct 23 17:26:33 UTC 2013 (Ubuntu 3.11.0-13.20-generic 3.11.6)
[    0.000000] KERNEL supported cpus:
[    0.000000]   Intel GenuineIntel
[    0.000000]   AMD AuthenticAMD
[    0.000000]   NSC Geode by NSC
[    0.000000]   Cyrix CyrixInstead
[    0.000000]   Centaur CentaurHauls
[    0.000000]   Transmeta GenuineTMx86
[    0.000000]   Transmeta TransmetaCPU
[    0.000000]   UMC UMC UMC UMC
[    0.000000] e820: BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
[    0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000007dc08bff] usable
[    0.000000] BIOS-e820: [mem 0x000000007dc08c00-0x000000007dc5cbff] ACPI NVS
[    0.000000] BIOS-e820: [mem 0x000000007dc5cc00-0x000000007dc5ebff] ACPI data
[    0.000000] BIOS-e820: [mem 0x000000007dc5ec00-0x000000007fffffff] reserved

```

### 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 -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@tecmint.com ~]# dmesg | tail -20

parport0: PC-style at 0x378, irq 7 [PCSPP,TRISTATE]
ppdev: user-space parallel port driver
EXT4-fs (sda1): mounted filesystem with ordered data mode
Adding 2097144k swap on /dev/sda2.  Priority:-1 extents:1 across:2097144k
readahead-disable-service: delaying service auditd
ip_tables: (C) 2000-2006 Netfilter Core Team
nf_conntrack version 0.5.0 (16384 buckets, 65536 max)
NET: Registered protocol family 10
lo: Disabled Privacy Extensions
e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
Slow work thread pool: Starting up
Slow work thread pool: Ready
FS-Cache: Loaded
CacheFiles: Loaded
CacheFiles: Security denies permission to nominate security context: error -95
eth0: no IPv6 routers present
type=1305 audit(1398268784.593:18630): audit_enabled=0 old=1 auid=4294967295 ses=4294967295 res=1
readahead-collector: starting delayed service auditd
readahead-collector: sorting
readahead-collector: finished

```

### 5. 搜索包含特定字符串的被检测到的硬件


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](http://www.tecmint.com/12-practical-examples-of-linux-grep-command/) 的‘**-i**’选项表示忽略大小写。



```
[root@tecmint.com log]# dmesg | grep -i usb
[root@tecmint.com log]# dmesg | grep -i dma
[root@tecmint.com log]# dmesg | grep -i tty
[root@tecmint.com log]# dmesg | grep -i memory

```

### 输出



```
[    0.000000] Scanning 1 areas for low memory corruption
[    0.000000] initial memory mapped: [mem 0x00000000-0x01ffffff]
[    0.000000] Base memory trampoline at [c009b000] 9b000 size 16384
[    0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff]
[    0.000000] init_memory_mapping: [mem 0x37800000-0x379fffff]
[    0.000000] init_memory_mapping: [mem 0x34000000-0x377fffff]
[    0.000000] init_memory_mapping: [mem 0x00100000-0x33ffffff]
[    0.000000] init_memory_mapping: [mem 0x37a00000-0x37bfdfff]
[    0.000000] Early memory node ranges
[    0.000000] PM: Registered nosave memory: [mem 0x0009f000-0x000effff]
[    0.000000] PM: Registered nosave memory: [mem 0x000f0000-0x000fffff]
[    0.000000] please try 'cgroup_disable=memory' option if you don't want memory cgroups
[    0.000000] Memory: 2003288K/2059928K available (6352K kernel code, 607K rwdata, 2640K rodata, 880K init, 908K bss, 56640K reserved, 1146920K highmem)
[    0.000000] virtual kernel memory layout:
[    0.004291] Initializing cgroup subsys memory
[    0.004609] Freeing SMP alternatives memory: 28K (c1a3e000 - c1a45000)
[    0.899622] Freeing initrd memory: 23616K (f51d0000 - f68e0000)
[    0.899813] Scanning for low memory corruption every 60 seconds
[    0.946323] agpgart-intel 0000:00:00.0: detected 32768K stolen memory
[    1.360318] Freeing unused kernel memory: 880K (c1962000 - c1a3e000)
[    1.429066] [drm] Memory usable by graphics device = 2048M

```

### 6. 清空dmesg缓冲区日志


我们可以使用如下命令来清空dmesg的日志。该命令会清空dmesg环形缓冲区中的日志。但是你依然可以查看存储在‘**/var/log/dmesg**’文件中的日志。你连接任何的设备都会产生dmesg日志输出。



```
[root@tecmint.com log]# dmesg -c

```

### 7. 实时监控dmesg日志输出


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@tecmint.com log]# watch "dmesg | tail -20"

```

**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。




---


[![](https://camo.githubusercontent.com/53d677032382a09e50d21d9ee15e621f7c5a7b5c/687474703a2f2f312e67726176617461722e636f6d2f6176617461722f33366337633235313634633334353566326637313162303165333935646530643f733d383026643d626c616e6b26723d47)](https://camo.githubusercontent.com/53d677032382a09e50d21d9ee15e621f7c5a7b5c/687474703a2f2f312e67726176617461722e636f6d2f6176617461722f33366337633235313634633334353566326637313162303165333935646530643f733d383026643d626c616e6b26723d47)


Narad Shrestha


* [Twitter profile](http://twitter.com/@nrdshrestha)
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他在IT领域拥有超过10年的丰富经验，其中包括各种Linux发行版，开源软件和网络工作。 Narad始终坚持与他人分享IT知识和自如地运用新技术。




---


via: <http://www.tecmint.com/dmesg-commands/>


译者：[cvsher](https://github.com/cvsher) 校对：[Caroline](https://github.com/carolinewuyan)


本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出