Wednesday, November 27, 2013

Configuring RelayHost in Sendmail

Let's assume the Mail RelayHost name is "".

Edit the following file /etc/mail/

define(`SMART_HOST', `')

# m4  /etc/mail/ > /etc/mail/

# Restart the Sendmail service
   /etc/init.d/sendmail restart

Converting Time from PST to IST

I have some monitoring scripts that captures the system statistics at a regular interval and writes it into a Logfile with system time, which is in PST.  When any incident happens during the IST hours, the concern Team in India reports us the problem with IST timing.  As a subsequent action, when I try to analyze the Logfile captured by the system, the timestamp in it was confusing me, as I need to match with IST time-interval that was reported.  So in order to easy my job, I came out with this solution of gathering the system statistics in IST but without changing the Timezone setting on the server.

TIME_IN_IST=`TZ='GMT-5:30' date +"%H:%M:%S %D IST"`

Sample Execution:
[root@linuxhost]# date
Tue Nov 26 20:00:37 PST 2013
[root@linuxhost]# date +"%H:%M:%S %D IST"
20:00:42 11/26/13 IST
[root@linuxhost]# TIME_IN_IST=`TZ='GMT-5:30' date +"%H:%M:%S %D IST"`
[root@linuxhost]# echo $TIME_IN_IST
09:30:46 11/27/13 IST
[root@linuxhost]# date
Tue Nov 26 20:00:54 PST 2013

How it works:
I have used GMT offset to match with IST, which is 13.5 hours ahead.  GMT for California is 8 hours behind "GMT-8.00"  and GMT for India is "GMT+5.30".  To match with India Timing, it has to be 13.5 (8+5.30) hours behind.