NAME
dmesg
—
display the system message
buffer
SYNOPSIS
dmesg |
[-a ] [-c ]
[-f[f] ] [-M
core] [-N
system] [-n
dumpnr] |
DESCRIPTION
Thedmesg
utility displays the contents of the system
message buffer. If neither the -N
nor the
-M
option is specified, the buffer is read from the
currently running kernel via the
sysctl(3) interface. Otherwise, the buffer is read from the specified
core file (or from the default one), using the name list from the specified
kernel image (or from the default image).
The options are as follows:
-a
- Show all data in the message buffer. This includes any syslog records and /dev/console output.
-c
- Clear the kernel buffer after printing.
-f[f]
- After the initial message buffer dump
dmesg
monitors the kernel for additional data and displays it as it arrives.dmesg
will not terminate until killed in this mode. If this option is specified twice,dmesg
will live loop (using the CPU heavily) to obtain updates as quickly as possible. This second mode should only be used when trying to debug a kernel crashing situation. -M
core- Extract values associated with the name list from the specified core instead of the default /dev/kmem.
-N
system- Extract the name list from the specified system instead of the default, which is the kernel image the system has booted from.
-n
dumpnr- Use the kernel core dump file numbered dumpnr for debugging.
FILES
- /var/run/dmesg.boot
- usually a snapshot of the buffer contents taken soon after file systems are mounted at startup time
SEE ALSO
HISTORY
The dmesg
utility appeared in
3.0BSD.