time/tzselect.ksh

   1 #! /bin/ksh
   2 # Ask the user about the time zone, and output the resulting TZ value to stdout.
   3 # Interact with the user via stderr and stdin.
   4
   5 # Contributed by Paul Eggert <eggert@twinsun.com>.
   6
   7 # Porting notes:
   8 #
   9 # This script requires several features of the Korn shell.
  10 # If your host lacks the Korn shell,
  11 # you can use either of the following free programs instead:
  12 #
  13 #       Bourne-Again shell (bash)
  14 #       <URL:ftp://prep.ai.mit.edu:/pub/gnu/bash-1.14.7.tar.gz>
  15 #       (or any later version)
  16 #
  17 #       Public domain ksh
  18 #       <URL:ftp://ftp.cs.mun.ca:/pub/pdksh/pdksh.tar.gz>
  19 #
  20 # This script also uses several features of modern awk programs.
  21 # If your host lacks awk, or has an old awk that does not conform to Posix.2,
  22 # you can use either of the following free programs instead:
  23 #
  24 #       GNU awk (gawk)
  25 #       <URL:ftp://prep.ai.mit.edu:/pub/gnu/gawk-3.0.0.tar.gz>
  26 #       (or any later version)
  27 #
  28 #       mawk
  29 #       <URL:ftp://oxy.edu/public/mawk1.2.2.tar.gz>
  30 #       (or any later version)
  31
  32
  33 # Specify default values for environment variables if they are unset.
  34 : ${AWK=awk}
  35 : ${TZDIR=$(pwd)}
  36
  37 # Check for awk Posix compliance.
  38 ($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
  39 [ $? = 123 ] || {
  40         echo >&2 "$0: Sorry, your \`$AWK' program is not Posix compatible."
  41         exit 1
  42 }
  43
  44 # Make sure the tables are readable.
  45 TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
  46 TZ_ZONE_TABLE=$TZDIR/zone.tab
  47 for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
  48 do
  49         <$f || {
  50                 echo >&2 "$0: time zone files are not set up correctly"
  51                 exit 1
  52         }
  53 done
  54
  55 newline='
  56 '
  57 IFS=$newline
  58
  59
  60 # Work around a bash bug, where $PS3 is sent to stdout.
  61 case $(echo 1 | (select x in x; do break; done) 2>/dev/null) in
  62 ?*) PS3=
  63 esac
  64
  65
  66 # Begin the main loop.  We come back here if the user wants to retry.
  67 while
  68
  69         echo >&2 'Please identify a location' \
  70                 'so that time zone rules can be set correctly.'
  71
  72         continent=
  73         country=
  74         region=
  75
  76
  77         # Ask the user for continent or ocean.
  78
  79         echo >&2 'Please select a continent or ocean.'
  80
  81         select continent in \
  82             Africa \
  83             Americas \
  84             Antarctica \
  85             'Arctic Ocean' \
  86             Asia \
  87             'Atlantic Ocean' \
  88             Australia \
  89             Europe \
  90             'Indian Ocean' \
  91             'Pacific Ocean' \
  92             'none - I want to specify the time zone using the Posix TZ format.'
  93         do
  94             case $continent in
  95             '')
  96                 echo >&2 'Please enter a number in range.';;
  97             ?*)
  98                 case $continent in
  99                 Americas) continent=America;;
 100                 *' '*) continent=$(expr "$continent" : '\([^ ]*\)')
 101                 esac
 102                 break
 103             esac
 104         done
 105         case $continent in
 106         '')
 107                 exit 1;;
 108         none)
 109                 # Ask the user for a Posix TZ string.  Check that it conforms.
 110                 while
 111                         echo >&2 'Please enter the desired value' \
 112                                 'of the TZ environment variable.'
 113                         echo >&2 'For example, GST-10 is a zone named GST' \
 114                                 'that is 10 hours ahead (east) of UTC.'
 115                         read TZ
 116                         $AWK -v TZ="$TZ" 'BEGIN {
 117                                 tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+"
 118                                 time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?"
 119                                 offset = "[-+]?" time
 120                                 date = "(J?[0-9]+|M[0-9]+\.[0-9]+\.[0-9]+)"
 121                                 datetime = "," date "(/" time ")?"
 122                                 tzpattern = "^(:.*|" tzname offset "(" tzname \
 123                                   "(" offset ")?(" datetime datetime ")?)?)$"
 124                                 if (TZ ~ tzpattern) exit 1
 125                                 exit 0
 126                         }'
 127                 do
 128                         echo >&2 "\`$TZ' is not a conforming" \
 129                                 'Posix time zone string.'
 130                 done
 131                 TZ_for_date=$TZ;;
 132         *)
 133                 # Get list of names of countries in the continent or ocean.
 134                 countries=$($AWK -F'\t' \
 135                         -v continent="$continent" \
 136                         -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
 137                 '
 138                         /^#/ { next }
 139                         $3 ~ ("^" continent "/") {
 140                                 if (!cc_seen[$1]++) cc_list[++ccs] = $1
 141                         }
 142                         END {
 143                                 while (getline <TZ_COUNTRY_TABLE) {
 144                                         if ($0 !~ /^#/) cc_name[$1] = $2
 145                                 }
 146                                 for (i = 1; i <= ccs; i++) {
 147                                         country = cc_list[i]
 148                                         if (cc_name[country]) {
 149                                           country = cc_name[country]
 150                                         }
 151                                         print country
 152                                 }
 153                         }
 154                 ' <$TZ_ZONE_TABLE | sort -f)
 155
 156
 157                 # If there's more than one country, ask the user which one.
 158                 case $countries in
 159                 *"$newline"*)
 160                         echo >&2 'Please select a country.'
 161                         select country in $countries
 162                         do
 163                             case $country in
 164                             '') echo >&2 'Please enter a number in range.';;
 165                             ?*) break
 166                             esac
 167                         done
 168
 169                         case $country in
 170                         '') exit 1
 171                         esac;;
 172                 *)
 173                         country=$countries
 174                 esac
 175
 176
 177                 # Get list of names of time zone rule regions in the country.
 178                 regions=$($AWK -F'\t' \
 179                         -v country="$country" \
 180                         -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
 181                 '
 182                         BEGIN {
 183                                 cc = country
 184                                 while (getline <TZ_COUNTRY_TABLE) {
 185                                         if ($0 !~ /^#/  &&  country == $2) {
 186                                                 cc = $1
 187                                                 break
 188                                         }
 189                                 }
 190                         }
 191                         $1 == cc { print $4 }
 192                 ' <$TZ_ZONE_TABLE)
 193
 194
 195                 # If there's more than one region, ask the user which one.
 196                 case $regions in
 197                 *"$newline"*)
 198                         echo >&2 'Please select one of the following' \
 199                                 'time zone regions.'
 200                         select region in $regions
 201                         do
 202                                 case $region in
 203                                 '') echo >&2 'Please enter a number in range.';;
 204                                 ?*) break
 205                                 esac
 206                         done
 207                         case $region in
 208                         '') exit 1
 209                         esac;;
 210                 *)
 211                         region=$regions
 212                 esac
 213
 214                 # Determine TZ from country and region.
 215                 TZ=$($AWK -F'\t' \
 216                         -v country="$country" \
 217                         -v region="$region" \
 218                         -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
 219                 '
 220                         BEGIN {
 221                                 cc = country
 222                                 while (getline <TZ_COUNTRY_TABLE) {
 223                                         if ($0 !~ /^#/  &&  country == $2) {
 224                                                 cc = $1
 225                                                 break
 226                                         }
 227                                 }
 228                         }
 229                         $1 == cc && $4 == region { print $3 }
 230                 ' <$TZ_ZONE_TABLE)
 231
 232                 # Make sure the corresponding zoneinfo file exists.
 233                 TZ_for_date=$TZDIR/$TZ
 234                 <$TZ_for_date || {
 235                         echo >&2 "$0: time zone files are not set up correctly"
 236                         exit 1
 237                 }
 238         esac
 239
 240
 241         # Use the proposed TZ to output the current date relative to UTC.
 242         # Loop until they agree in seconds.
 243         # Give up after 8 unsuccessful tries.
 244
 245         extra_info=
 246         for i in 1 2 3 4 5 6 7 8
 247         do
 248                 TZdate=$(LANG=C TZ="$TZ_for_date" date)
 249                 UTdate=$(LANG=C TZ=UTC0 date)
 250                 TZsec=$(expr "$TZdate" : '.*:\([0-5][0-9]\)')
 251                 UTsec=$(expr "$UTdate" : '.*:\([0-5][0-9]\)')
 252                 case $TZsec in
 253                 $UTsec)
 254                         extra_info="
 255 Local time is now:      $TZdate.
 256 Universal Time is now:  $UTdate."
 257                         break
 258                 esac
 259         done
 260
 261
 262         # Output TZ info and ask the user to confirm.
 263
 264         echo >&2 ""
 265         echo >&2 "The following information has been given:"
 266         echo >&2 ""
 267         case $country+$region in
 268         ?*+?*)  echo >&2 "      $country$newline        $region";;
 269         ?*+)    echo >&2 "      $country";;
 270         +)      echo >&2 "      TZ='$TZ'"
 271         esac
 272         echo >&2 ""
 273         echo >&2 "Therefore TZ='$TZ' will be used.$extra_info"
 274         echo >&2 "Is the above information OK?"
 275
 276         ok=
 277         select ok in Yes No
 278         do
 279             case $ok in
 280             '') echo >&2 'Please enter 1 for Yes, or 2 for No.';;
 281             ?*) break
 282             esac
 283         done
 284         case $ok in
 285         '') exit 1;;
 286         Yes) break
 287         esac
 288 do :
 289 done
 290
 291 # Output the answer.
 292 echo "$TZ"