Linux/Unix Shell Scripting - Tratamiento de fechas en script Unix

#! /usr/bin/ksh

. ~/.profile

arcDate=`date +%Y%m%d%H%M%S`

currentday=`date +%Y%m%d`

MAIL="evillasmil@tracfone.com "

OFFSET=${1:-3}

case $OFFSET in

*[!0-9]* | ???* | 3? | 29) print -u2 "Invalid input" ; exit 1;;

esac

eval `date "+day=%d; month=%m; year=%Y`

typeset -Z2 day month

typeset -Z4 year

# Subtract offset from day, if it goes below one use 'cal'

# to determine the number of days in the previous month.

day=$((day - OFFSET))

if (( day <= 0 )) ;then

month=$((month - 1))

if (( month == 0 )) ;then

year=$((year - 1))

month=12

fi

set -A days `cal $month $year`

xday=${days[$(( ${#days[*]}-1 ))]}

day=$((xday + day))

fi

IN3DAYS=$year$month$day

echo $IN3DAYS

v_path="/HOME/estoyaqui"

CONEXION="usuario/clave@BD"

GEN_FECHA()

{

${ORACLE_HOME}/bin/sqlplus -s <<EOF>FECHA_PROCESO.DAT

${CONEXION}

Set verify off

Set pages 0

Set lines 200

Set head off

Set feedback off

Col a format 990

Spool '${v_path}'/ejecucion_arg.out

select lpad(to_char(sysdate-7, 'dd/mm/YYYY'), 10, 0) from dual;

Spool Off

EOF

EJECUCION_ARG=`cat ${v_path}/FECHA_PROCESO.DAT | grep '/' | awk '{print $1}' `;  export EJECUCION_ARG

}

GEN_FECHA; # llama la funcion

v_date=${EJECUCION_ARG} # asigna resultado