How to find the time in unix ?

vskgopu · 05-14-2006, 10:28 PM

Hi friends,

I want to get the time, but i dont want to use the system time..coz somebody may change it.

I am implementing a SMTP relay server to delay the mails for some "x"-minutes. so that i have to check the time. In this place i cant use the systme time,coz as i said somebody can change it.
Is there any other clock in unix..machines..runnning uniquely..regardless of the system time?

Note : I dont want to get the exact time. I just want a clock to find the delay time.

Plz help me...
Thanks in advance....

Simon Bridge · 05-14-2006, 10:46 PM

usleep?
http://www.die.net/doc/linux/man/man3/usleep.3.html

or sleep(1)

Code:

SLEEP(1)                                     User Commands                                     SLEEP(1)

NAME
       sleep - delay for a specified amount of time

SYNOPSIS
       sleep NUMBER[SUFFIX]...
       sleep OPTION

DESCRIPTION
       Pause for NUMBER seconds.  SUFFIX may be ‘s’ for seconds (the default), ‘m’ for minutes, ‘h’ for
       hours or ‘d’ for days.  Unlike most implementations that require NUMBER be an integer, here NUM‐
       BER may be an arbitrary floating point number.

       --help display this help and exit

       --version
              output version information and exit

AUTHOR
       Written by Jim Meyering and Paul Eggert.

vskgopu · 05-15-2006, 02:36 AM

Thanks friend i got the solution by using the 'times' call it gives the number of ticks elapsed since the system has been up..
Any how thanks a lot..

timmeke · 05-15-2006, 05:11 AM

Any PC, regardless of the operating system, always maintains it's own time on a hardware clock.
Unfortunately, those clocks are known to be inaccurate and -as you already pointed out yourself- the users
can alter the time/date.

If you want to get the universally correct time, you should consider setting up NTP to retrieve
the exact time from a world-wide server.

Likewise, once you got one machine that queries those servers, you can setup your other machines to contact your first machine, thus "propagating" the correct time accross your machines.

Have a look at:
man ntpd

nx5000 · 05-15-2006, 05:36 AM

Quote:

Originally Posted by vskgopu

I want to get the time, but i dont want to use the system time..coz somebody may change it.

Only root can change it.

vskgopu · 05-15-2006, 07:48 AM

thanks friends

timmeke · 05-16-2006, 02:03 AM

You're welcome.