Re: Linux

[Bob Proulx]

CK Lim wrote:
> I try to help a friend who has some problem with display the system date
> and time.
> 
> My friend has a application running on red hat linux. The application
> always display the system date and time to the led display.

What is this "led display" that you are talking about?

> When the battery for the "CMOS" is weak, the date and time shifted. That
> display on the led will be incorrect.

It sounds as if your hardware clock battery is failing and therefore
the hardware clock is not keeping correct time when the system is not
running.  After a reboot the time will be incorrect.

The usual solution is to run an NTP daemon to correct the clock at
boot time and to keep the clock correct during normal system
operation.

  http://en.wikipedia.org/wiki/Network_Time_Protocol

What operating system are you running?  You didn't say.  For example
on Debian installing the "ntp" package is usually sufficient.

  # apt-get install ntp

But of course other systems will be different.

> we would like to set the system date and time to "nothing",,, so that the
> application will display nothing on the led for date and time.

On Unix-like systems there isn't really a way to set the time to
nothing.  All time is reference from the "Unix epoch" of 00:00:00 UTC
on 1 January 1970.  That is zero seconds.

  http://en.wikipedia.org/wiki/Unix_time

The best answer is to correct the clock.  And perhaps replace the
battery.  But if the network is available then the net can be used for
a time base to correct the clock at boot time and during normal operation.

Bob