如何用shell 实现某天减1天的日期

[littlekuku1]

如何用shell 实现某天减1天的日期：

[littlekuku1]

谢谢

[gdream]

#!/bin/sh

CurYear=`date +%Y`
CurMonth=`date +%m`
CurDay=`date +%d`


GetYear="$CurYear"
GetMonth="$CurMonth"
GetDay="`expr $CurDay - 1`"


if [ "$GetDay" -le 0 ] ; then

GetMonth=`expr $CurMonth - 1`

if [ "$GetMonth" -le 0 ] ; then

GetYear=`expr $CurYear - 1`
GetMonth=12

fi

case "$GetMonth"
in
1|3|5|7|8|10|12)

GetDay=31;;
4|6|9|11)

GetDay=30;;
2)

if [ `expr "$CurYear" % 400` -eq 0 ] ; then

GetDay=29
elif [ `expr "$CurYear" % 4` -eq 0 -a `expr "$CurYear" % 100` -ne 0 ] ; then

GetDay=29
else

GetDay=28
fi
esac

fi

if [ `echo "$GetMonth" | wc -m` -ne 3 ] ; then

GetMonth=0$GetMonth
fi

if [ `echo "$GetDay" | wc -m` -ne 3 ] ; then

GetDay=0$GetDay
fi


echo
echo " === Get Last Date ==="
echo
echo "\t\t""$GetYear""$GetMonth""$GetDay"
echo