JezK
Edit File: tzselect
#!/usr/bin/bash PKGVERSION="(GNU libc) " TZVERSION="2.17" REPORT_BUGS_TO="<http://www.gnu.org/software/libc/bugs.html>" # Ask the user about the time zone, and output the resulting TZ value to stdout. # Interact with the user via stderr and stdin. # Contributed by Paul Eggert. # Porting notes: # # This script requires a Posix-like shell with the extension of a # 'select' statement. The 'select' statement was introduced in the # Korn shell and is available in Bash and other shell implementations. # If your host lacks both Bash and the Korn shell, you can get their # source from one of these locations: # # Bash <http://www.gnu.org/software/bash/bash.html> # Korn Shell <http://www.kornshell.com/> # Public Domain Korn Shell <http://www.cs.mun.ca/~michael/pdksh/> # # This script also uses several features of modern awk programs. # If your host lacks awk, or has an old awk that does not conform to Posix, # you can use either of the following free programs instead: # # Gawk (GNU awk) <http://www.gnu.org/software/gawk/> # mawk <http://invisible-island.net/mawk/> # Specify default values for environment variables if they are unset. : ${AWK=awk} : ${TZDIR=/usr/share/zoneinfo} # Check for awk Posix compliance. ($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1 [ $? = 123 ] || { echo >&2 "$0: Sorry, your \`$AWK' program is not Posix compatible." exit 1 } if [ "$1" = "--help" ]; then cat <<EOF Usage: tzselect Select a time zone interactively. Report bugs to $REPORT_BUGS_TO. EOF exit elif [ "$1" = "--version" ]; then cat <<EOF tzselect $PKGVERSION$TZVERSION EOF exit fi # Make sure the tables are readable. TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab TZ_ZONE_TABLE=$TZDIR/zone.tab for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE do <$f || { echo >&2 "$0: time zone files are not set up correctly" exit 1 } done newline=' ' IFS=$newline # Work around a bug in bash 1.14.7 and earlier, where $PS3 is sent to stdout. case $(echo 1 | (select x in x; do break; done) 2>/dev/null) in ?*) PS3= esac # Begin the main loop. We come back here if the user wants to retry. while echo >&2 'Please identify a location' \ 'so that time zone rules can be set correctly.' continent= country= region= # Ask the user for continent or ocean. echo >&2 'Please select a continent or ocean.' select continent in \ Africa \ Americas \ Antarctica \ 'Arctic Ocean' \ Asia \ 'Atlantic Ocean' \ Australia \ Europe \ 'Indian Ocean' \ 'Pacific Ocean' \ 'none - I want to specify the time zone using the Posix TZ format.' do case $continent in '') echo >&2 'Please enter a number in range.';; ?*) case $continent in Americas) continent=America;; *' '*) continent=$(expr "$continent" : '\([^ ]*\)') esac break esac done case $continent in '') exit 1;; none) # Ask the user for a Posix TZ string. Check that it conforms. while echo >&2 'Please enter the desired value' \ 'of the TZ environment variable.' echo >&2 'For example, GST-10 is a zone named GST' \ 'that is 10 hours ahead (east) of UTC.' read TZ $AWK -v TZ="$TZ" 'BEGIN { tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+" time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?" offset = "[-+]?" time date = "(J?[0-9]+|M[0-9]+\.[0-9]+\.[0-9]+)" datetime = "," date "(/" time ")?" tzpattern = "^(:.*|" tzname offset "(" tzname \ "(" offset ")?(" datetime datetime ")?)?)$" if (TZ ~ tzpattern) exit 1 exit 0 }' do echo >&2 "\`$TZ' is not a conforming" \ 'Posix time zone string.' done TZ_for_date=$TZ;; *) # Get list of names of countries in the continent or ocean. countries=$($AWK -F'\t' \ -v continent="$continent" \ -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \ ' /^#/ { next } $3 ~ ("^" continent "/") { if (!cc_seen[$1]++) cc_list[++ccs] = $1 } END { while (getline <TZ_COUNTRY_TABLE) { if ($0 !~ /^#/) cc_name[$1] = $2 } for (i = 1; i <= ccs; i++) { country = cc_list[i] if (cc_name[country]) { country = cc_name[country] } print country } } ' <$TZ_ZONE_TABLE | sort -f) # If there's more than one country, ask the user which one. case $countries in *"$newline"*) echo >&2 'Please select a country.' select country in $countries do case $country in '') echo >&2 'Please enter a number in range.';; ?*) break esac done case $country in '') exit 1 esac;; *) country=$countries esac # Get list of names of time zone rule regions in the country. regions=$($AWK -F'\t' \ -v country="$country" \ -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \ ' BEGIN { cc = country while (getline <TZ_COUNTRY_TABLE) { if ($0 !~ /^#/ && country == $2) { cc = $1 break } } } $1 == cc { print $4 } ' <$TZ_ZONE_TABLE) # If there's more than one region, ask the user which one. case $regions in *"$newline"*) echo >&2 'Please select one of the following' \ 'time zone regions.' select region in $regions do case $region in '') echo >&2 'Please enter a number in range.';; ?*) break esac done case $region in '') exit 1 esac;; *) region=$regions esac # Determine TZ from country and region. TZ=$($AWK -F'\t' \ -v country="$country" \ -v region="$region" \ -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \ ' BEGIN { cc = country while (getline <TZ_COUNTRY_TABLE) { if ($0 !~ /^#/ && country == $2) { cc = $1 break } } } $1 == cc && $4 == region { print $3 } ' <$TZ_ZONE_TABLE) # Make sure the corresponding zoneinfo file exists. TZ_for_date=$TZDIR/$TZ <$TZ_for_date || { echo >&2 "$0: time zone files are not set up correctly" exit 1 } esac # Use the proposed TZ to output the current date relative to UTC. # Loop until they agree in seconds. # Give up after 8 unsuccessful tries. extra_info= for i in 1 2 3 4 5 6 7 8 do TZdate=$(LANG=C TZ="$TZ_for_date" date) UTdate=$(LANG=C TZ=UTC0 date) TZsec=$(expr "$TZdate" : '.*:\([0-5][0-9]\)') UTsec=$(expr "$UTdate" : '.*:\([0-5][0-9]\)') case $TZsec in $UTsec) extra_info=" Local time is now: $TZdate. Universal Time is now: $UTdate." break esac done # Output TZ info and ask the user to confirm. echo >&2 "" echo >&2 "The following information has been given:" echo >&2 "" case $country+$region in ?*+?*) echo >&2 " $country$newline $region";; ?*+) echo >&2 " $country";; +) echo >&2 " TZ='$TZ'" esac echo >&2 "" echo >&2 "Therefore TZ='$TZ' will be used.$extra_info" echo >&2 "Is the above information OK?" ok= select ok in Yes No do case $ok in '') echo >&2 'Please enter 1 for Yes, or 2 for No.';; ?*) break esac done case $ok in '') exit 1;; Yes) break esac do : done case $SHELL in *csh) file=.login line="setenv TZ '$TZ'";; *) file=.profile line="TZ='$TZ'; export TZ" esac echo >&2 " You can make this change permanent for yourself by appending the line $line to the file '$file' in your home directory; then log out and log in again. Here is that TZ value again, this time on standard output so that you can use the $0 command in shell scripts:" echo "$TZ"