Is DST in effect?

[Craig Sterley]

How can i determine via a script is Daylight Savings Time is in effect or not?

[James R. Ferguson · Accepted solution]

Hi Craig:

# perl -le '$dst=(localtime)[8];print $dst==1 ? "in DST":"not in DST"'

...is an easy way to answer your question.

Regards!

...JRF...

[Craig Sterley]

Thank you for the quick response. That did the trick.

[Craig Sterley]

case closed. Thanks again

[Matti_Kurkela]

A shell script solution: examine the timezone identifier (available with "date +%Z").

For example, at the US West Coast, it should return PST when using Standard Time and PDT when the Daylight Saving Time is in effect.

This can be made timezone-agnostic by using the fact that the only thing we need to know is whether the current timezone identifier is at the beginning of the TZ value, or at the end.

Disclaimer: quick&dirty, with very little testing. If it breaks, you can keep the pieces.

#!/bin/sh
NOW=$(date +%Z)
if [ ${TZ#$NOW} != ${TZ} ]
then
echo "Standard time"
elif [ ${TZ%$NOW} != ${TZ} ]
then
echo "Daylight time"
else
echo "ERROR: date command outputted a timezone identifier not listed in TZ"
fi

MK