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HP-UX 11i Version 3: February 2007

Technical documentation

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dmesg — collect system diagnostic messages to form error log


/usr/sbin/dmesg [-] [core] [system]


dmesg looks in a system buffer for recently printed diagnostic messages and prints them on the standard output. The messages are those printed by the system when unusual events occur (such as when system tables overflow or the system crashes). If the - argument is specified, dmesg computes (incrementally) the new messages since the last time it was run and places these on the standard output. This is typically used with cron (see cron(1)) to produce the error log /var/adm/messages by running the command:

/usr/sbin/dmesg - >> /var/adm/messages

every 10 minutes.

The arguments core and system allow substitution for the defaults /dev/kmem and /stand/vmunix respectively, where core should be a file containing the image of the kernel virtual memory saved by the savecrash(1M) command and system should be the corresponding kernel. If the system is booted with a kernel other than /stand/vmunix say /stand/vmunix_new, dmesg must be passed this name, the command must be,

/usr/sbin/dmesg [-] /dev/kmem /stand/vmunix_new


The system error message buffer is of small, finite size. dmesg is run only every few minutes, so there is no guarantee that all error messages will be logged.


dmesg was developed by the University of California, Berkeley.



error log (conventional location)


memory scratch file for - option


special file containing the image of kernel virtual memory


the kernel, system name list



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