daylight saving time

[chad_c]

how do i ensure my HPUX 11.11i servers are set to auto adjust for daylight saving time?

[A. Clay Stephenson · Accepted solution]

Run the attached Perl script, dst.pl. Invoke as dst.pl -u for full usage but you can simply run as "dst.pl" to display the exact second before and after the transition. If you are running multiple TZ's then test it thusly:

TZ=EST5EDT dst.pl
TZ=CST6CDT dst.pl
TZ=MST7MDT dst.pl

You many need to change to "shebang" line from #!/usr/bin/perl to something like "#!/opt/perl5/bin/perl" or create a softlink from your perl install bin to /usr/bin/perl.

Because this Perl scripts uses the same underlying libc functions as do the standard commands like date, if this work then the other utilities work as well.

[chad_c]

does the script just verify that the time is adjusted accordingly?

[A. Clay Stephenson]

What it actually does is find the very first and last seconds in a given year. It then converges on the exact seconds that the localtime() isdst field changes. When those transition points are found strftime() is called to display seconds - 1 and seconds for each transition.

The bottom line it that this is a method that uses the same standard routines that UNIX commands and programs use -- so if this works and displays the expected times then the others also work when that time comes.

Bear in mind that your UNIX box does not actually change time; it simply counts seconds since 00:00:00 1-Jan-1970 UTC. What changes is the way these epoch seconds are displayed. HP-UX is unique in that the time transitions are controlled by a textfile, /usr/lib/tztab. Man tztab for details.

[A. Clay Stephenson]

By the way, if you happen to have TZ settings that do not change (either by intent or accident) then dst.pl returns a null result and sets the exit code to a non-zero value.

e.g.

TZ=GMT0 dst.pl -d
STAT=${?}
echo "Status = ${STAT}"

[chad_c]

so in other words if i see the following output, then the server is going to auto adjust according to daylight saving :)

txovo# perl /tmp/tz.pl
Sun Apr 02 01:59:59 CST 2006 --> Sun Apr 02 03:00:00 CDT 2006
Sun Oct 29 01:59:59 CDT 2006 --> Sun Oct 29 01:00:00 CST 2006

[chad_c]

so in other words if i see the following output, then the server is going to auto adjust (or i should say 'accurately reflect') according to daylight saving :)

txovo# perl /tmp/tz.pl
Sun Apr 02 01:59:59 CST 2006 --> Sun Apr 02 03:00:00 CDT 2006
Sun Oct 29 01:59:59 CDT 2006 --> Sun Oct 29 01:00:00 CST 2006

[Steven E. Protter]

Shalom chad,

Answer to last question: Yes.

SEP

[A. Clay Stephenson]

Does a hog like slop? Is the Pope Catholic?

[chad_c]

someone always has to be a smart A$$

[chad_c]

however, to answer your question as to whether a hog likes slop, you may have to go and ask the pope

thanks for the info.

[A. Clay Stephenson]

No, having slopped hogs at an early age, I can assure you that they eat it (and generally anything else) with great relish.