zdump -v America/Sao_Paulo |grep 200[78]
America/Sao_Paulo Sun Feb 25 01:59:59 2007 UTC = Sat Feb 24 23:59:59 2007 BRST isdst=1 gmtoff=-7200
America/Sao_Paulo Sun Feb 25 02:00:00 2007 UTC = Sat Feb 24 23:00:00 2007 BRT isdst=0 gmtoff=-10800
America/Sao_Paulo Sun Nov 4 02:59:59 2007 UTC = Sat Nov 3 23:59:59 2007 BRT isdst=0 gmtoff=-10800
America/Sao_Paulo Sun Nov 4 03:00:00 2007 UTC = Sun Nov 4 01:00:00 2007 BRST isdst=1 gmtoff=-7200
America/Sao_Paulo Sun Feb 24 01:59:59 2008 UTC = Sat Feb 23 23:59:59 2008 BRST isdst=1 gmtoff=-7200
America/Sao_Paulo Sun Feb 24 02:00:00 2008 UTC = Sat Feb 23 23:00:00 2008 BRT isdst=0 gmtoff=-10800
America/Sao_Paulo Sun Nov 2 02:59:59 2008 UTC = Sat Nov 1 23:59:59 2008 BRT isdst=0 gmtoff=-10800
America/Sao_Paulo Sun Nov 2 03:00:00 2008 UTC = Sun Nov 2 01:00:00 2008 BRST isdst=1 gmtoff=-7200