Re: Suppressing kernel 'printk's.

[Nate Bargmann <n0nb@n0nb.us>]

Further searching resulted in this message:

http://lists.debian.org/debian-user/2007/03/msg01554.html

of which this snippet is key:

The settings in /etc/sysctl.conf take effect at the next reboot. You can
change the printk setting with immediate effect with 

echo "4 1 1 7" > /proc/sys/kernel/printk

and you can check the setting with

cat /proc/sys/kernel/printk

Only root can change the setting but everyone can read it.

The files in /proc/ are pseudo-files which provide interfaces to kernel
data structures; see "man proc" for details.

===========

excerpt from
/usr/share/doc/linux-doc-2.6.20/Documentation/sysctl/kernel.txt.gz
follows:

==============================================================

printk:

The four values in printk denote: console_loglevel,
default_message_loglevel, minimum_console_loglevel and
default_console_loglevel respectively.

These values influence printk() behavior when printing or
logging error messages. See 'man 2 syslog' for more info on
the different loglevels.

- console_loglevel: messages with a higher priority than
  this will be printed to the console
- default_message_level: messages without an explicit priority
  will be printed with this priority
- minimum_console_loglevel: minimum (highest) value to which
  console_loglevel can be set
- default_console_loglevel: default value for console_loglevel

==============================================================


For the numeric values the following from the syslog(2) manpage is
useful:

Every text line in a message has its own loglevel.  This level  is 
DEFAULT_MESSAGE_LOGLEVEL  - 1 (6) unless the line starts with <d> where
d is a digit in the range 1-7, in which case the level  is  d.   The 
conventional  meaning  of  the loglevel is defined in <linux/kernel.h>
as follows: 

       #define KERN_EMERG    "<0>"  /* system is unusable               */
       #define KERN_ALERT    "<1>"  /* action must be taken immediately */
       #define KERN_CRIT     "<2>"  /* critical conditions              */
       #define KERN_ERR      "<3>"  /* error conditions                 */
       #define KERN_WARNING  "<4>"  /* warning conditions               */
       #define KERN_NOTICE   "<5>"  /* normal but significant condition */
       #define KERN_INFO     "<6>"  /* informational                    */
       #define KERN_DEBUG    "<7>"  /* debug-level messages             */


- Nate >>

-- 

"The optimist proclaims that we live in the best of all
possible worlds.  The pessimist fears this is true."