WikiDevi.Wi-Cat.RU:DD-WRT/dmesg command

dmesg (for "diagnostic message") is a command on Unix-like operating systems that prints the message buffer of the kernel. This buffer contains a variety of important messages from those printed during boot to those used for debugging software. This information may also be stored to disk via a logging daemon, such as syslog.

dmesg is often piped to tail for an easier overview of recent events:

dmesg | tail

Example output on a Linksys WRT54G router (with CPU overclocked) running DD-WRT v24rc4:

root@WikiDevi:DD-WRT/~# dmesg CPU revision is: 00029008 Linux version 2.4.35 (root@dd-wrt) (gcc version 3.4.4 (OpenWrt-2.0)) #2530 Wed Oct 10 02:19:55 CEST 2007 Setting the PFC to its default value Determined physical RAM map: memory: 01000000 @ 00000000 (usable) On node 0 totalpages: 4096 zone(0): 4096 pages. zone(1): 0 pages. zone(2): 0 pages. Kernel command line: root=/dev/mtdblock2 rootfstype=squashfs,jffs2 noinitrd console=ttyS0,115200 CPU: BCM5352 rev 0 at 250 MHz Using 125.000 MHz high precision timer. Calibrating delay loop... 249.03 BogoMIPS Dentry cache hash table entries: 2048 (order: 2, 16384 bytes) Inode cache hash table entries: 1024 (order: 1, 8192 bytes) Mount cache hash table entries: 512 (order: 0, 4096 bytes) Buffer cache hash table entries: 1024 (order: 0, 4096 bytes) Page-cache hash table entries: 4096 (order: 2, 16384 bytes) Checking for 'wait' instruction... unavailable. POSIX conformance testing by UNIFIX PCI: no core PCI: Fixing up bus 0 Initializing RT netlink socket Starting kswapd devfs: v1.12c (20020818) Richard Gooch (rgooch@atnf.csiro.au) devfs: boot_options: 0x1 squashfs: version 3.0 (2006/03/15) Phillip Lougher pty: 256 Unix98 ptys configured Serial driver version 5.05c (2001-07-08) with MANY_PORTS SHARE_IRQ SERIAL_PCI enabled ttyS00 at 0xb8000300 (irq = 3) is a 16550A ttyS01 at 0xb8000400 (irq = 3) is a 16550A Software Watchdog Timer: 0.05, timer margin: 60 sec PCI: Setting latency timer of device 00:01.0 to 64 Universal TUN/TAP device driver 1.5 (C)1999-2002 Maxim Krasnyansky Physically mapped flash: Found an alias at 0x400000 for the chip at 0x0 Physically mapped flash: Found an alias at 0x800000 for the chip at 0x0 Physically mapped flash: Found an alias at 0xc00000 for the chip at 0x0 Physically mapped flash: Found an alias at 0x1000000 for the chip at 0x0 Physically mapped flash: Found an alias at 0x1400000 for the chip at 0x0 Physically mapped flash: Found an alias at 0x1800000 for the chip at 0x0 Physically mapped flash: Found an alias at 0x1c00000 for the chip at 0x0 Amd/Fujitsu Extended Query Table v3.3 at 0x0040 number of CFI chips: 1 cfi_cmdset_0002: Disabling fast programming due to code brokenness. Flash device: 0x400000 at 0x1c000000 bootloader size: 262144 Physically mapped flash: Filesystem type: squashfs, size=0x2d1f7c Creating 5 MTD partitions on "Physically mapped flash": 0x00000000-0x00040000 : "cfe" 0x00040000-0x003f0000 : "linux" 0x000c98c8-0x003a0000 : "rootfs" mtd: partition "rootfs" doesn't start on an erase block boundary -- force read-only 0x003f0000-0x00400000 : "nvram" 0x003a0000-0x003f0000 : "ddwrt" Initializing Cryptographic API IP Protocols: ICMP, UDP, TCP, IGMP IP: routing cache hash table of 512 buckets, 4Kbytes TCP: Hash tables configured (established 1024 bind 2048) ip_conntrack version 2.1 (512 buckets, 4096 max) - 336 bytes per conntrack ip_tables: (C) 2000-2002 Netfilter core team ipt_random match loaded netfilter PSD loaded - (c) astaro AG ipt_osf: Startng OS fingerprint matching module. ipt_IPV4OPTSSTRIP loaded NET4: Unix domain sockets 1.0/SMP for Linux NET4.0. 802.1Q VLAN Support v1.8 Ben Greear  All bugs added by David S. Miller  VFS: Mounted root (squashfs filesystem) readonly. Mounted devfs on /dev diag boardtype: 00000467 PCI: Setting latency timer of device 00:05.0 to 64 eth1: Broadcom BCM4320 802.11 Wireless Controller 4.80.56.0 vlan0: add 01:00:5e:00:00:01 mcast address to master interface vlan0: dev_set_promiscuity(master, 1) device eth0 entered promiscuous mode device vlan0 entered promiscuous mode device eth1 entered promiscuous mode vlan1: Setting MAC address to 00 1c 10 5a b9 0d. vlan1: add 01:00:5e:00:00:01 mcast address to master interface vlan1: dev_set_promiscuity(master, 1) device vlan1 entered promiscuous mode vlan1: dev_set_allmulti(master, 1) device br0 entered promiscuous mode vlan1: dev_set_allmulti(master, 1) vlan1: add 01:00:5e:7f:ff:fa mcast address to master interface vlan0: dev_set_promiscuity(master, -1) device vlan0 left promiscuous mode device eth1 left promiscuous mode vlan0: dev_set_promiscuity(master, 1) device vlan0 entered promiscuous mode device eth1 entered promiscuous mode device br0 left promiscuous mode

Source: http://en.wikipedia.org/wiki/Dmesg