Dmesg command

From NetworkCommands

A command available on most Linux platforms; used to display the kernel message buffer. Kernel messages include those displayed during system boot as well as messages generated by system events and software during normal operation.

Usage Syntax

dmesg [options]

Common options include;

-c - clear the message bugger after displaying it's current contents.

Usage Examples

dmesg

Usage Notes

The kernel message buffer is a ring buffer, meaning that when the buffer becomes full, new messages overwrite the oldest messages in the buffer. The default buffer size is 16384.

This command can be particularly useful when connecting removable media and other devices to the system as it's output will provide information on where the device has been mapped to in the file system.

Linux Usage Notes

With most Linux or Unix commands;

Brief help can be displayed using the option/keyword: -h or --help, for example: chmod --help
A full command manual can be displayed using the man command followed by the command name, for example: man chmod
Sometimes 'info' pages are used instead of or to provide more information than man pages; for example: info chmod
Version information can be display using the option/keyword: -v or --version, for example: chmod --version

Typical Output

F5 BigIP 1500 running v9 software;

[user@device-one:Standby] / # '''dmesg | tail -n 50'''
kjournald starting.  Commit interval 5 seconds
EXT3-fs: ide0(3,5): orphan cleanup on readonly fs
ext3_orphan_cleanup: deleting unreferenced inode 80617
ext3_orphan_cleanup: deleting unreferenced inode 80618
EXT3-fs: ide0(3,5): 2 orphan inodes deleted
EXT3-fs: recovery complete.
EXT3-fs: mounted filesystem with ordered data mode.
Freeing unused kernel memory: 224k freed
usb.c: registered new driver hiddev
usb.c: registered new driver hid
hid-core.c: v1.8.1 Andreas Gal, Vojtech Pavlik <vojtech@suse.cz>
hid-core.c: USB HID support drivers
mice: PS/2 mouse device common for all mice
EXT3 FS 2.4-0.9.19, 19 August 2002 on ide0(3,5), internal journal
Adding Swap: 3086880k swap-space (priority -1)
kjournald starting.  Commit interval 5 seconds
EXT3 FS 2.4-0.9.19, 19 August 2002 on ide0(3,7), internal journal
EXT3-fs: mounted filesystem with ordered data mode.
kjournald starting.  Commit interval 5 seconds
EXT3 FS 2.4-0.9.19, 19 August 2002 on ide0(3,8), internal journal
EXT3-fs: mounted filesystem with ordered data mode.
kjournald starting.  Commit interval 5 seconds
EXT3 FS 2.4-0.9.19, 19 August 2002 on ide0(3,9), internal journal
EXT3-fs: mounted filesystem with ordered data mode.
kjournald starting.  Commit interval 5 seconds
EXT3 FS 2.4-0.9.19, 19 August 2002 on ide0(3,1), internal journal
EXT3-fs: mounted filesystem with ordered data mode.
kjournald starting.  Commit interval 5 seconds
EXT3-fs warning: checktime reached, running e2fsck is recommended
EXT3 FS 2.4-0.9.19, 19 August 2002 on loop(7,0), internal journal
ext3_orphan_cleanup: deleting unreferenced inode 32454
EXT3-fs: loop(7,0): 1 orphan inode deleted
EXT3-fs: recovery complete.
EXT3-fs: mounted filesystem with ordered data mode.
IPv6 v0.8 for NET4.0
IPv6 over IPv4 tunneling driver
i2c-i801 version 2.10.0 (20060214)
i2c-dev.o: i2c /dev entries driver module version 2.10.0 (20060214)
i2c-dev.o: Registered 'SMBus I801 adapter at 0500' as minor 0
Non-volatile memory driver v1.2
Universal VNIC device driver v1.0.  Max packets per poll: 4096.
Auto Last Hop kernel module
microcode: CPU0 updated from revision 0x17 to 0x2e, date = 08112004
SubDomain: SubDomain (version 24imnx1.1) initialized
Disabled Privacy Extensions on device 024a42c0(lo)
e1000: eth0: e1000_watchdog: NIC Link is Up 100 Mbps Full Duplex
eth0: no IPv6 routers present
tmm0: no IPv6 routers present
vlan1: no IPv6 routers present
vlan2: no IPv6 routers present