A recent screwup involving forecast time zone changes made me hack together this little ditty.

#!/bin/sh

if [ "x$1" != "x" ]; then
    zone=`find /usr/share/zoneinfo -iwholename "*"$1"*" | head -1`
else
    zone=/etc/localtime
fi
year=`date +%Y`
echo $zone
zdump -v $zone | grep $year | cut -f2- -d' '

Some uses:

% tzinfo Brussels
/usr/share/zoneinfo/posix/Europe/Brussels
 Sun Mar 29 00:59:59 2009 UTC = Sun Mar 29 01:59:59 2009 CET isdst=0 gmtoff=3600
 Sun Mar 29 01:00:00 2009 UTC = Sun Mar 29 03:00:00 2009 CEST isdst=1 gmtoff=7200
 Sun Oct 25 00:59:59 2009 UTC = Sun Oct 25 02:59:59 2009 CEST isdst=1 gmtoff=7200
 Sun Oct 25 01:00:00 2009 UTC = Sun Oct 25 02:00:00 2009 CET isdst=0 gmtoff=3600

% tzinfo
/etc/localtime
 Sun Mar  8 06:59:59 2009 UTC = Sun Mar  8 01:59:59 2009 EST isdst=0 gmtoff=-18000
 Sun Mar  8 07:00:00 2009 UTC = Sun Mar  8 03:00:00 2009 EDT isdst=1 gmtoff=-14400
 Sun Nov  1 05:59:59 2009 UTC = Sun Nov  1 01:59:59 2009 EDT isdst=1 gmtoff=-14400
 Sun Nov  1 06:00:00 2009 UTC = Sun Nov  1 01:00:00 2009 EST isdst=0 gmtoff=-18000