DST Fixes for Redhat and GNU/Linux

Notes:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1096277&admit=-682735245+1171291626422+28353475

http://www.faqs.org/docs/Linux-HOWTO/TimePrecision-HOWTO.html

http://www.macosxhints.com/article.php?story=20070128185822710

Note if localtime is a link or an independant file:

# ls -al /etc/localtime
-rw-r--r--    1 root     root         1267 Sep  9  2002 /etc/localtime

Determine if your zone data is set correctly for 2007:

# zdump -v /etc/localtime | grep 2007
/etc/localtime  Sun Apr  1 06:59:59 2007 UTC = Sun Apr  1 01:59:59 2007 EST
isdst=0 gmtoff=-18000
/etc/localtime  Sun Apr  1 07:00:00 2007 UTC = Sun Apr  1 03:00:00 2007 EDT
isdst=1 gmtoff=-14400
/etc/localtime  Sun Oct 28 05:59:59 2007 UTC = Sun Oct 28 01:59:59 2007 EDT
isdst=1 gmtoff=-14400
/etc/localtime  Sun Oct 28 06:00:00 2007 UTC = Sun Oct 28 01:00:00 2007 EST
isdst=0 gmtoff=-18000

Download the latest time zone data from NIST:

ftp://elsie.nci.nih.gov/pub/tzdata2007c.tar.gz

Save the file to /usr/local/admin/dst

# cd /usr/local/admin/dst
# tar zxvf tzdata2007c.tar.gz

Now archive the existing zonedata if it is not a link:

# cp /etc/localtime /etc/localtime.20070212.kinscoe

Now compile the new North America file:

# cd /usr/local/admin/dst
# zic northamerica

Verify the new DST file is correct for 2007:

# zdump -v /usr/share/zoneinfo/EST5EDT | grep 2007

Link to the new DST zone file:

# rm /etc/localtime
# ln -s /usr/share/zoneinfo/EST5EDT /etc/localtime
# ls -l /etc/localtime
lrwxrwxrwx    1 root     root           27 Jan 12 11:04 /etc/localtime ->
/usr/share/zoneinfo/EST5EDT

Run the timechange tool:

# timeconfig "EST5EDT"

Testing:

# date 03110159
Sun Mar 11 01:59:00 EST 2007
# sleep 60; date
Sun Mar 11 03:00:22 EDT 2007

Now test your C Library:

date -d '1970-01-01 UTC +1173679260 seconds'
Mon Mar 12 01:01:00 EST 2007