Guessing the date style from the timezone for postgresql postinst
In order to help remove unnecessary prompts from the Debian PostgreSQLl
installation script, I want it to guess the local date style, to be chosen
from the following list:
Style Date Datetime
-------------------------------------------------------
ISO 1999-07-17 1999-07-17 07:09:18+01
SQL 17/07/1999 17/07/1999 07:09:19.00 BST
POSTGRES 17-07-1999 Sat 17 Jul 07:09:19 1999 BST
GERMAN 17.07.1999 17.07.1999 07:09:19.00 BST
NONEURO 07-17-1999 Sat Jul 17 07:09:19 1999 BST
US 07-17-1999 Sat Jul 17 07:09:19 1999 BST
EURO 17-07-1999 Sat 17 Jul 07:09:19 1999 BST
I propose to include the attached script. If the zone belongs to USA or
Canada, I use American format; if it belongs to another country I use
European format; if the country is unidentified I try to guess from
the zone abbreviation and its offset from UTC. For zones which aren't based
on regional names I use ISO.
Are there any other countries besides USA and Canada which use American
datestyle? Am I right in thinking that Canada does?
If you have a recent potato system, with timezone files in
/usr/share/zoneinfo, could you please run the script and let me know if
it gives WRONG results for you. If it does, please tell me your timezone
and offset (date '+%Z %z') and what the date style ought to be. If you
can suggest a change to the script that will get it right without breaking
results for other countries, that will be even better!
Please do NOT tell me if it is RIGHT or I will be overwhelmed with mail!
If anyone wants to see the result for all timezones, this Bourne shell
fragment will do it:
(cd /usr/share/zoneinfo;
for TZ in `find * -type f ! -name '*.tab' ! -name localtime`
do echo -en `date '+%Z %z'` \\t $TZ \\t
/tmp/guess.datestyle
done |
awk '{printf "%7s %5s %40s %2s %s %s\n",$1, $2, $3, $4, $5, $6}' |
less)
#! /bin/sh
# Guess the postgresql datestyle to use for a given timezone (from glibc)
# make sure we can find the timezone database
ZONEDIR=/usr/share/zoneinfo
if [ ! -d "$ZONEDIR" ]
then
echo "Sorry, I don't know where to find the timezone files; this
script expected to find them in $ZONEDIR"
exit 1
fi
# make sure TZ is set and exported
if [ -z "$TZ" ]
then
TZ=`date '+%Z'`
fi
export TZ
# find the timezone offset from UTC
tzno=`date '+%z'`
# Find the name of the zone - strip off unwanted header directories
x=`echo $TZ | cut -d/ -f1`
case $x in ( SystemV | posix | right )
x=`echo $TZ | cut -d/ -f2-4`
;;
* )
x=$TZ
;;
esac
# What country does this zone belong to (if undefined, set it to __)
tzcountry=`grep $x $ZONEDIR/zone.tab | head -1 | cut -c1-2`
if [ -z "$tzcountry" ]
then
tzcountry=__
fi
# Guess the timezone
case $tzcountry in ( US | CA )
# US date format
# (I assume Canada uses US format)
GuessDateStyle=US
;;
DE )
# Germany has a style to itself
GuessDateStyle=GERMAN
;;
__ )
# No country, so see if the zone is a region or country name
x=$TZ
while echo $x | grep -q /
do
y=`dirname $x`
case $y in ( SystemV | posix | right )
y=`basename $x`
;;
esac
x=$y
done
case $x in ( Africa | Canada | Indian | Mexico | America | Chile | GB | Iran | Mideast | Antarctica | Cuba | Israel | NZ | Singapore | Arctic | Jamaica | Asia | Japan | Navajo | Turkey | Atlantic | Kwajalein | Australia | Egypt | Libya | US | Brazil | Eire | Pacific | Hongkong | Poland | Europe | Iceland | Portugal)
# try to guess the zone from the UTC offset and the
# zone abbreviation
if [ -z "$GuessDateStyle" ]
then
GuessDateStyle=EURO
# if the user has German locale, I assume
# he will want GERMAN style
if [ "$LANG" = de_DE ]
then
GuessDateStyle=GERMAN
elif [ $tzno -le -200 -a $tzno -gt -1200 ]
then
tzn=`date '+%Z'`
case $tzn in ( ADT | AST | AKDT | AKST | CDT | CST | EDT | EST | HADT | HAST | HST | MDT | MST | NDT | PDT | PST)
GuessDateStyle=US
;;
esac
fi
fi
;;
* )
# Not a country or region, so use ISO
GuessDateStyle=ISO
;;
esac
;;
* )
# The rest of the world uses normal European format
GuessDateStyle=EURO
;;
esac
echo $tzcountry $GuessDateStyle
exit 0
# The End
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========================================
Oliver Elphick Oliver.Elphick@lfix.co.uk
Isle of Wight http://www.lfix.co.uk/oliver
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firstfruits of all thine increase; So shall thy barns
be filled with plenty, and thy presses shall burst out
with new wine." Proverbs 3:9,10
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