timezone/tzselect.ksh

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