Dmesg command
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- | # | + | 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: | ||
+ | |||
+ | <pre>root@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 <greearb@candelatech.com> | ||
+ | All bugs added by David S. Miller <davem@redhat.com> | ||
+ | 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</pre> | ||
+ | |||
+ | Source: http://en.wikipedia.org/wiki/Dmesg | ||
+ | |||
+ | [[Category:Kernel]] | ||
+ | [[Category:Maturity level]] | ||
+ | [[Category:Command-line reference]] |
Current revision
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@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 <greearb@candelatech.com> All bugs added by David S. Miller <davem@redhat.com> 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