在Shell中使用日期运算和比较

脚本内容大概主要包括以下： 1、有且只有两个输入参数，都是必输项。 2、参数的格式是日期且格式是“yyyyMMdd"(如：20140101) 3、第二个参数一定要比第一个参数晚 4、最终的执行结果就是将两个日期区间的日期打印出来。

#!/bin/bash
startDate="$1"
endDate="$2"
DATE_FMT="%Y%m%d"
 
source ./log.sh
export DEBUG="true"
 
function showUsage() { 
    warn ""
    warn "------------------------ Usage ----------------------------- "
    warn " Syntax:  checkInputDates.sh <start date> <end date>"
    warn ""
    warn " Remark: " 
    warn "   1.Two arguments are required and must with format 'YYYYmmDD'."
    warn "   2.Named 'end date' argument must be greater then or equal to 'start date' argument."
    warn ""
    warn "  Example: checkInputDates.sh 20140102 20140901" 
    warn "------------------------------------------------------------ "
}
 
DATE_FMT=${DATE_FMT:-"%Y%m%d"} ##Default with format "%Y%m%d",eg: 20140102
function checkDateValid() {
    local myDate=$1
    local exp="date +$DATE_FMT -d $myDate"
    if [ "$myDate" == "`$exp`" ]; then
        echo "1"
    else 
        echo "0"
    fi  
} 
 
###
##  TODO: It's not correctly.
##
function datesDiff() {
    local d1=`date -d "$1" +%s`
    local d2=`date -d "$2" +%s`
    ##debug "Dates: "$d1 $d2
    local cr=$(($d1-$d2)); ##Diff in 'day' unit.
    echo $cr
}
 
 
 
##
#  Return the day after input date.
# Usage: toTomorrow <input date>
##
function compareDates() { 
 
    ## `date -d " 20141225 1 day" +%Y%m%d`
    local cr=$(datesDiff $1 $2); ##Diff in 'day' unit.
    ##debug "Compare: $(($(date +$DATE_FMT -d $1) - $(date +$DATE_FMT -d $2)));"; 
    if [[ $cr -eq 0 ]]; then 
        echo "0"
    elif [[ $cr -gt 0 ]]; then
        echo "1"
    else 
        echo "-1"  
    fi
}
 
##
#  Return the day after input date.
# Usage: toTomorrow <input date>
##
function toTomorrow() {
 
    local curDate="$1"
    ##debug $curDate
     
    ##TODO: Must be adapted to DATE_FMT... 
    ##curDate="${curDate:0:4}-${curDate:4:2}-${curDate:6:2}"
     
    ##debug "date -d '$curDate +1 day ' +$DATE_FMT"
    ##echo `date -d "$curDate +1 day " +$DATE_FMT`
    ##echo `date +$DATE_FMT -d "1 day $curDate"`
    echo `date -d "1 day $curDate" +$DATE_FMT`
}
 
function countStrsByBlank() {
    ##local str="$1"
    ##local sep="${2:-' '}" 
    ##echo $str |  awk -v v="$sep" '{ split($0,a,v);for(i in a) {c=i;}} END {print c;}'
  set j=0
  for item in $dates
  do
    let j=j+1
  done
  echo $j
}
 
##
#  Get the diff date list between input two dates.
# Usage: getDiffDateList <end date> <start date>
##
function getDiffDateList() {
 
    local endd=$1
    local stad=$2
    dl=() 
    while [[ "$stad" != "$endd" ]]
    do
        dl=(${dl[*]} "$stad")
        stad=$(toTomorrow $stad)
    done
    dl=(${dl[*]} "$stad")
    echo "${dl[*]}"
}
###### Check inputs ################ 
#1. Only two arguments.
warn ""
if [ $# != 2 ]; then
    warn "ERROR: Only support two arguments input." | showUsage 
    exit 1;
fi 
 
#2. Check if they're the leagal value.
tmpSd=$(checkDateValid $startDate) 
if [ "$tmpSd" == "0" ]; then ###It's the invalid date. eg: 20141901
    warn "ERROR: Invalid 'start date' with input '$startDate',it must be with format 'yyyyMMdd',eg: 20140101" | showUsage
    exit 1;   
fi   
tmpEd=$(checkDateValid $endDate) 
if [ "$tmpEd" == "0" ]; then ###It's the invalid date. eg: 20141901 
    warn "ERROR: Invalid 'end date' with input '$startDate',eg: 20140101" 
    exit 1;
fi
 
#3. Check the arg2 greater than or equal arg1.
##echo "Compare result: "$(compareDates $endDate $startDate)
cprs=$(compareDates $endDate $startDate) 
if [ "$cprs" == "-1" ]; then
    warn "ERROR: The first argument must not greater than the second one!" | showUsage 
    exit 1;
fi
######################################
##loop the dates between start and end date.
while [[ "$startDate" != "$endDate" ]]
do
    echo $startDate
    startDate=$(toTomorrow $startDate)
done