[Tcl-bugs] [ tcl-Bugs-940278 ] env(TZ) has delayed effect on clock format

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Bugs item #940278, was opened at 2004-04-22 22:03
Message generated for change (Comment added) made by davidw
You can respond by visiting: 
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Category: 06. Time Measurement
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: David N. Welton (davidw)
Assigned to: Kevin B KENNY (kennykb)
Summary: env(TZ) has delayed effect on clock format

Initial Comment:
This script:
----
if { ! [info exists env(TZ) ] } {
    set myTZ ""
} else {
    set myTZ $env(TZ)
}

puts "Local time is [clock format [clock seconds]]"
set env(TZ) GMT+8
puts "Time in Eugene, Oregon is [clock format [clock
seconds]]"
set env(TZ) GMT-1
puts "Time in Padua, Italy is [clock format [clock
seconds]]"

if { $myTZ == "" } {
    unset env(TZ)
} else {
    set env(TZ) $myTZ
}
----

does not produce the desired results, in either 8.4.6
or 8.5.

kbk found that HAVE_TZSET is not tested for in the
configure scripts, except for some crufty unix systems.
 He also proposed commenting out the calledTzset = 1;
on or around line 285.

Further bulletins as events warrant.

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>Comment By: David N. Welton (davidw)
Date: 2004-04-23 23:15

Message:
Logged In: YES 
user_id=240

It seems as if the problem may be that localtime_r does not
call tzset, as normal localtime does.

Note that there are also some discrepencies between
tclUnixThrd.c and tclUnixTime.c.  The first globally
redefines localtime, whereas the second also checks if
HAVE_LOCALTIME_R is defined.  This conflict ought to be
resolved.

----------------------------------------------------------------------

Comment By: David N. Welton (davidw)
Date: 2004-04-22 22:44

Message:
Logged In: YES 
user_id=240

This works on my system (linux, modern kernel, modern glibc):

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main()
{
    time_t thetime = 0;
    struct tm *tms;

    time(&thetime);
    setenv("TZ", "GMT-1", 1);
    tms = localtime(&thetime);
    printf("padova hour %d\n", tms->tm_hour);
    setenv("TZ", "GMT+8", 1);
    tms = localtime(&thetime);
    printf("eugene hour %d\n", tms->tm_hour);

}


----------------------------------------------------------------------

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