timezone/tzselect.ksh

   1 #! @KSH@
   2
   3 # '@(#)tzselect.ksh     1.8'
   4
   5 # Ask the user about the time zone, and output the resulting TZ value to stdout.
   6 # Interact with the user via stderr and stdin.
   7
   8 # Contributed by Paul Eggert.
   9
  10 # Porting notes:
  11 #
  12 # This script requires several features of the Korn shell.
  13 # If your host lacks the Korn shell,
  14 # you can use either of the following free programs instead:
  15 #
  16 #       <a href=ftp://ftp.gnu.org/pub/gnu/>
  17 #       Bourne-Again shell (bash)
  18 #       </a>
  19 #
  20 #       <a href=ftp://ftp.cs.mun.ca/pub/pdksh/pdksh.tar.gz>
  21 #       Public domain ksh
  22 #       </a>
  23 #
  24 # This script also uses several features of modern awk programs.
  25 # If your host lacks awk, or has an old awk that does not conform to Posix.2,
  26 # you can use either of the following free programs instead:
  27 #
  28 #       <a href=ftp://ftp.gnu.org/pub/gnu/>
  29 #       GNU awk (gawk)
  30 #       </a>
  31 #
  32 #       <a href=ftp://ftp.whidbey.net/pub/brennan/>
  33 #       mawk
  34 #       </a>
  35
  36
  37 # Specify default values for environment variables if they are unset.
  38 : ${AWK=awk}
  39 : ${TZDIR=@TZDIR@}
  40
  41 # Check for awk Posix compliance.
  42 ($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
  43 [ $? = 123 ] || {
  44         echo >&2 "$0: Sorry, your \`$AWK' program is not Posix compatible."
  45         exit 1
  46 }
  47
  48 # Make sure the tables are readable.
  49 TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
  50 TZ_ZONE_TABLE=$TZDIR/zone.tab
  51 for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
  52 do
  53         <$f || {
  54                 echo >&2 "$0: time zone files are not set up correctly"
  55                 exit 1
  56         }
  57 done
  58
  59 newline='
  60 '
  61 IFS=$newline
  62
  63
  64 # Work around a bug in bash 1.14.7 and earlier, where $PS3 is sent to stdout.
  65 case $(echo 1 | (select x in x; do break; done) 2>/dev/null) in
  66 ?*) PS3=
  67 esac
  68
  69
  70 # Begin the main loop.  We come back here if the user wants to retry.
  71 while
  72
  73         echo >&2 'Please identify a location' \
  74                 'so that time zone rules can be set correctly.'
  75
  76         continent=
  77         country=
  78         region=
  79
  80
  81         # Ask the user for continent or ocean.
  82
  83         echo >&2 'Please select a continent or ocean.'
  84
  85         select continent in \
  86             Africa \
  87             Americas \
  88             Antarctica \
  89             'Arctic Ocean' \
  90             Asia \
  91             'Atlantic Ocean' \
  92             Australia \
  93             Europe \
  94             'Indian Ocean' \
  95             'Pacific Ocean' \
  96             'none - I want to specify the time zone using the Posix TZ format.'
  97         do
  98             case $continent in
  99             '')
 100                 echo >&2 'Please enter a number in range.';;
 101             ?*)
 102                 case $continent in
 103                 Americas) continent=America;;
 104                 *' '*) continent=$(expr "$continent" : '\([^ ]*\)')
 105                 esac
 106                 break
 107             esac
 108         done
 109         case $continent in
 110         '')
 111                 exit 1;;
 112         none)
 113                 # Ask the user for a Posix TZ string.  Check that it conforms.
 114                 while
 115                         echo >&2 'Please enter the desired value' \
 116                                 'of the TZ environment variable.'
 117                         echo >&2 'For example, GST-10 is a zone named GST' \
 118                                 'that is 10 hours ahead (east) of UTC.'
 119                         read TZ
 120                         $AWK -v TZ="$TZ" 'BEGIN {
 121                                 tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+"
 122                                 time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?"
 123                                 offset = "[-+]?" time
 124                                 date = "(J?[0-9]+|M[0-9]+\.[0-9]+\.[0-9]+)"
 125                                 datetime = "," date "(/" time ")?"
 126                                 tzpattern = "^(:.*|" tzname offset "(" tzname \
 127                                   "(" offset ")?(" datetime datetime ")?)?)$"
 128                                 if (TZ ~ tzpattern) exit 1
 129                                 exit 0
 130                         }'
 131                 do
 132                         echo >&2 "\`$TZ' is not a conforming" \
 133                                 'Posix time zone string.'
 134                 done
 135                 TZ_for_date=$TZ;;
 136         *)
 137                 # Get list of names of countries in the continent or ocean.
 138                 countries=$($AWK -F'\t' \
 139                         -v continent="$continent" \
 140                         -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
 141                 '
 142                         /^#/ { next }
 143                         $3 ~ ("^" continent "/") {
 144                                 if (!cc_seen[$1]++) cc_list[++ccs] = $1
 145                         }
 146                         END {
 147                                 while (getline <TZ_COUNTRY_TABLE) {
 148                                         if ($0 !~ /^#/) cc_name[$1] = $2
 149                                 }
 150                                 for (i = 1; i <= ccs; i++) {
 151                                         country = cc_list[i]
 152                                         if (cc_name[country]) {
 153                                           country = cc_name[country]
 154                                         }
 155                                         print country
 156                                 }
 157                         }
 158                 ' <$TZ_ZONE_TABLE | sort -f)
 159
 160
 161                 # If there's more than one country, ask the user which one.
 162                 case $countries in
 163                 *"$newline"*)
 164                         echo >&2 'Please select a country.'
 165                         select country in $countries
 166                         do
 167                             case $country in
 168                             '') echo >&2 'Please enter a number in range.';;
 169                             ?*) break
 170                             esac
 171                         done
 172
 173                         case $country in
 174                         '') exit 1
 175                         esac;;
 176                 *)
 177                         country=$countries
 178                 esac
 179
 180
 181                 # Get list of names of time zone rule regions in the country.
 182                 regions=$($AWK -F'\t' \
 183                         -v country="$country" \
 184                         -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
 185                 '
 186                         BEGIN {
 187                                 cc = country
 188                                 while (getline <TZ_COUNTRY_TABLE) {
 189                                         if ($0 !~ /^#/  &&  country == $2) {
 190                                                 cc = $1
 191                                                 break
 192                                         }
 193                                 }
 194                         }
 195                         $1 == cc { print $4 }
 196                 ' <$TZ_ZONE_TABLE)
 197
 198
 199                 # If there's more than one region, ask the user which one.
 200                 case $regions in
 201                 *"$newline"*)
 202                         echo >&2 'Please select one of the following' \
 203                                 'time zone regions.'
 204                         select region in $regions
 205                         do
 206                                 case $region in
 207                                 '') echo >&2 'Please enter a number in range.';;
 208                                 ?*) break
 209                                 esac
 210                         done
 211                         case $region in
 212                         '') exit 1
 213                         esac;;
 214                 *)
 215                         region=$regions
 216                 esac
 217
 218                 # Determine TZ from country and region.
 219                 TZ=$($AWK -F'\t' \
 220                         -v country="$country" \
 221                         -v region="$region" \
 222                         -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
 223                 '
 224                         BEGIN {
 225                                 cc = country
 226                                 while (getline <TZ_COUNTRY_TABLE) {
 227                                         if ($0 !~ /^#/  &&  country == $2) {
 228                                                 cc = $1
 229                                                 break
 230                                         }
 231                                 }
 232                         }
 233                         $1 == cc && $4 == region { print $3 }
 234                 ' <$TZ_ZONE_TABLE)
 235
 236                 # Make sure the corresponding zoneinfo file exists.
 237                 TZ_for_date=$TZDIR/$TZ
 238                 <$TZ_for_date || {
 239                         echo >&2 "$0: time zone files are not set up correctly"
 240                         exit 1
 241                 }
 242         esac
 243
 244
 245         # Use the proposed TZ to output the current date relative to UTC.
 246         # Loop until they agree in seconds.
 247         # Give up after 8 unsuccessful tries.
 248
 249         extra_info=
 250         for i in 1 2 3 4 5 6 7 8
 251         do
 252                 TZdate=$(LANG=C TZ="$TZ_for_date" date)
 253                 UTdate=$(LANG=C TZ=UTC0 date)
 254                 TZsec=$(expr "$TZdate" : '.*:\([0-5][0-9]\)')
 255                 UTsec=$(expr "$UTdate" : '.*:\([0-5][0-9]\)')
 256                 case $TZsec in
 257                 $UTsec)
 258                         extra_info="
 259 Local time is now:      $TZdate.
 260 Universal Time is now:  $UTdate."
 261                         break
 262                 esac
 263         done
 264
 265
 266         # Output TZ info and ask the user to confirm.
 267
 268         echo >&2 ""
 269         echo >&2 "The following information has been given:"
 270         echo >&2 ""
 271         case $country+$region in
 272         ?*+?*)  echo >&2 "      $country$newline        $region";;
 273         ?*+)    echo >&2 "      $country";;
 274         +)      echo >&2 "      TZ='$TZ'"
 275         esac
 276         echo >&2 ""
 277         echo >&2 "Therefore TZ='$TZ' will be used.$extra_info"
 278         echo >&2 "Is the above information OK?"
 279
 280         ok=
 281         select ok in Yes No
 282         do
 283             case $ok in
 284             '') echo >&2 'Please enter 1 for Yes, or 2 for No.';;
 285             ?*) break
 286             esac
 287         done
 288         case $ok in
 289         '') exit 1;;
 290         Yes) break
 291         esac
 292 do :
 293 done
 294
 295 case $SHELL in
 296 *csh) file=.login line="setenv TZ '$TZ'";;
 297 *) file=.profile line="TZ='$TZ'; export TZ"
 298 esac
 299
 300 echo >&2 "
 301 You can make this change permanent for yourself by appending the line
 302         $line
 303 to the file '$file' in your home directory; then log out and log in again.
 304
 305 Here is that TZ value again, this time on standard output so that you
 306 can use the $0 command in shell scripts:"
 307
 308 echo "$TZ"