On Mon, 1 Aug 2005, Mike McCarty wrote:
Craig White wrote:
On Mon, 2005-08-01 at 14:40 -0500, Mike McCarty wrote:
Dotan Cohen wrote:
On 8/1/05, Mike McCarty <mike.mccarty@xxxxxxxxxxxxx> wrote:
Would you please explain to me how my machine automagically knows it
needs to change the content of a file on its disc when the legislature
makes a change to the way DST works?
it doesn't so millions of pc have to be patched or updated.
<snip>
How does one get through to you? I ALREADY KNOW HOW TO USE YUM. I KNOW
HOW IT WORKS. READ WHAT I WROTE.
You again responded to what you read rather than what I asked.
Is English your first/primary language?
The purpose of my questions is to point out that the fellow wanted to
know how to update the files *HIMSELF* and the only responses he's
getting are from people like you who cannot/will not respond to the
question AS ASKED.
The answer to my question, AS ASKED, is "It is impossible for your
machine automatically to change the configuration files by itself
when your local government passes a new ordinance."
And the answer to the OP's question is so far not yet given.
The magic that switches unix style sysems for regular to daylight saving
and back is the timezone description file typically /etc/localtime which
is in tzfile format.
for info on the format look at:
man 5 tzfile
for a treatment of the functions in libc that support this. and actually
output the time:
man localtime
For systems where the system clock is utc/gmt (the right way to set your
time imho) the tzset function derives local time from the timezone file
set in your environment (which practically speaking means everyone on
the machine can have a different localtime represented (or more than one).
man tzset
unix/posix time is measured as the number of seconds elapsed since 0000
utc jan 1 1970. the unix day increases by exactly 86400 second per day
plus the occasional discontinious leap second to keep the unix day in sync
with the earths rotation. unix time is represented in your kernel as a
signed 32 bit int and all time on a posix system is fundamentaly derived
from unix time.
see:
http://en.wikipedia.org/wiki/Unix_time
for a more complete treatment on posix time.
joelja
Mike
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Joel Jaeggli Unix Consulting joelja@xxxxxxxxxxxxxxxxxxxx
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