mirror of https://github.com/tLDP/LDP
43 lines
1.4 KiB
Bash
43 lines
1.4 KiB
Bash
#!/bin/bash
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# date-calc.sh
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# Author: Nathan Coulter
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# Used in ABS Guide with permission (thanks!).
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MPHR=60 # Minutes per hour.
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HPD=24 # Hours per day.
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diff () {
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printf '%s' $(( $(date -u -d"$TARGET" +%s) -
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$(date -u -d"$CURRENT" +%s)))
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# %d = day of month.
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}
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CURRENT=$(date -u -d '2007-09-01 17:30:24' '+%F %T.%N %Z')
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TARGET=$(date -u -d'2007-12-25 12:30:00' '+%F %T.%N %Z')
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# %F = full date, %T = %H:%M:%S, %N = nanoseconds, %Z = time zone.
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printf '\nIn 2007, %s ' \
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"$(date -d"$CURRENT +
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$(( $(diff) /$MPHR /$MPHR /$HPD / 2 )) days" '+%d %B')"
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# %B = name of month ^ halfway
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printf 'was halfway between %s ' "$(date -d"$CURRENT" '+%d %B')"
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printf 'and %s\n' "$(date -d"$TARGET" '+%d %B')"
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printf '\nOn %s at %s, there were\n' \
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$(date -u -d"$CURRENT" +%F) $(date -u -d"$CURRENT" +%T)
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DAYS=$(( $(diff) / $MPHR / $MPHR / $HPD ))
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CURRENT=$(date -d"$CURRENT +$DAYS days" '+%F %T.%N %Z')
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HOURS=$(( $(diff) / $MPHR / $MPHR ))
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CURRENT=$(date -d"$CURRENT +$HOURS hours" '+%F %T.%N %Z')
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MINUTES=$(( $(diff) / $MPHR ))
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CURRENT=$(date -d"$CURRENT +$MINUTES minutes" '+%F %T.%N %Z')
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printf '%s days, %s hours, ' "$DAYS" "$HOURS"
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printf '%s minutes, and %s seconds ' "$MINUTES" "$(diff)"
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printf 'until Christmas Dinner!\n\n'
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# Exercise:
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# --------
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# Rewrite the diff () function to accept passed parameters,
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#+ rather than using global variables.
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