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