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fromdate_k93
#!/usr/bin/ksh93
################################################################
function usagemsg_fromdate_k93 {
print "
Program: fromdate_k93
This script calculates a date forward or backward for a
specified number of days from a given date.
Usage: ${1##*/} [-?] [-v] [-V] [-b beginDate] [-d days]
Where:
'-b' = Beginning date from which to start calculation.
Default value is today's date in the following
numeric format: 'YYYYMMDD'.
'-d' = Number of days to add or subtract from today's
date. Value can be positive or negative, if
negative, quote the value on the command line.
Default value is '-30' days
'-v' = Verbose mode
'-V' = Very Verbose Mode
Example: fromdate_k93 -b '20060320' -d '-30'
Author: Dana French (dfrench@mtxia.com) Copyright 2006
\"AutoContent\" enabled"
return 0
}
################################################################
function fromdate_k93
{
typeset TRUE="0"
typeset FALSE="1"
typeset VERBOSE="${FALSE}"
typeset VERYVERB="${FALSE}"
typeset BEGINDATE=$( date +"%Y%m%d" )
typeset DELTADAYS='-30'
typeset VERSION="1.0"
while getopts ":b#d#vV" OPTION
do
case "${OPTION}" in
'b') BEGINDATE="${OPTARG}";;
'd') DELTADAYS="${OPTARG}";;
'v') VERBOSE="${TRUE}";;
'V') VERYVERB="${TRUE}";;
'?') usagemsg_fromdate_k93 "${0}" && return 1;;
':') usagemsg_fromdate_k93 "${0}" && return 1;;
'#') usagemsg_fromdate_k93 "${0}" && return 1;;
esac
done
shift $(( ${OPTIND} - 1 ))
(( VERBOSE == TRUE )) && print -u 2 -- "# fromdate Version.......: ${VERSION}"
(( VERYVERB == TRUE )) && set -x
typeset YEAR="${BEGINDATE:0:4}"
typeset MON="${BEGINDATE:4:2}"
typeset DAY="${BEGINDATE:6:2}"
typeset DAYCNT="${DELTADAYS}"
(( VERBOSE == TRUE )) && print -u 2 -- "# Beginning Date.........: ${BEGINDATE}"
(( VERBOSE == TRUE )) && print -u 2 -- "# Beginning Year.........: ${YEAR}"
(( VERBOSE == TRUE )) && print -u 2 -- "# Beginning Month........: ${MON}"
(( VERBOSE == TRUE )) && print -u 2 -- "# Beginning Day of Month.: ${DAY}"
(( VERBOSE == TRUE )) && print -u 2 -- "# Number of Days Delta...: ${DELTADAYS}"
SMO=( nul jan feb mar apr may jun jul aug sep oct nov dec )
DIM=( 0 31 28 31 30 31 30 31 31 30 31 30 31 )
DIM[2]="28"
( ( (( ( YEAR % 4 ) == 0 )) &&
(( ( YEAR % 100 ) != 0 )) ) ||
(( ( YEAR % 400 ) == 0 )) ) &&
DIM[2]="29"
(( DAY = DAY + DAYCNT ))
################################################################
####
#### Determine if the specified year is a leap year, if so
#### modify the number of days in february. This must be
#### done differently if subtracting days from the current
#### date than for adding days. As a result two separate
#### loops are used depending upon whether days are being
#### added or subtracted from the current date.
####
#### The following is the loop for subtracting days from
#### the specified date.
####
################################################################
while (( DAY <= 0 ))
do
(( --MON ))
while (( MON <= 0 ))
do
(( MON = 12 - MON ))
(( YEAR = YEAR - 1 ))
done
(( VERBOSE == TRUE )) && print -u 2 -- "# YEAR % 4 ............: $(( YEAR % 4 ))"
(( VERBOSE == TRUE )) && print -u 2 -- "# YEAR % 100 ............: $(( YEAR % 100 ))"
(( VERBOSE == TRUE )) && print -u 2 -- "# YEAR % 400 ............: $(( YEAR % 400 ))"
DIM[2]="28"
( ( (( ( YEAR % 4 ) == 0 )) &&
(( ( YEAR % 100 ) != 0 )) ) ||
(( ( YEAR % 400 ) == 0 )) ) &&
DIM[2]="29"
(( DAY = ${DIM[MON]} + DAY ))
done
################################################################
####
#### The following is the loop for adding days to
#### the specified date.
####
################################################################
while (( DAY > ${DIM[MON]} ))
do
(( VERBOSE == TRUE )) && print -u 2 -- "# YEAR % 4 ............: $(( YEAR % 4 ))"
(( VERBOSE == TRUE )) && print -u 2 -- "# YEAR % 100 ............: $(( YEAR % 100 ))"
(( VERBOSE == TRUE )) && print -u 2 -- "# YEAR % 400 ............: $(( YEAR % 400 ))"
DIM[2]="28"
( ( (( ( YEAR % 4 ) == 0 )) &&
(( ( YEAR % 100 ) != 0 )) ) ||
(( ( YEAR % 400 ) == 0 )) ) &&
DIM[2]="29"
(( DAY = DAY - ${DIM[MON]} ))
(( ++MON ))
while (( MON > 12 ))
do
(( MON = MON - 12 ))
(( YEAR = YEAR + 1 ))
done
done
(( VERBOSE == TRUE )) && print -u 2 -- "# Days in Feb ${YEAR}.......: ${DIM[2]}"
typeset -Z4 YEAR4="${YEAR}"
typeset -Z2 MON2="${MON}"
typeset -Z2 DAY2="${DAY}"
print -- "${YEAR4}${MON2}${DAY2}"
return 0
}
################################################################
fromdate_k93 "${@}"
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