备份文件的脚本

此shell脚本程序，可以实现对备份文件进行更名：要求每次最新备份的数据存放到backupfile文本文件中，之前备份的文件更名为backupfile1，再之前备份的文件更名为backupfile2，依次类推backupfilen，不对n的数量做限制。

#!/bin/sh
#check the input
if [ ! -e $1 ]; then
    echo "Usage: ./backup filename"
    echo "The file must be exit"
    exit 1
fi;

#get the max file num
max=0
n=0
for file in `ls /tmp/backup`; do
    #n=`echo backupfile1 | sed 's/backupfile//'`
    n=${file#backupfile}
    if [ $n ];then
        if [ $n -gt $max ] ;then
            max=$n
        fi
    fi
done

#backup files
i=$max
pwd=`pwd`
cd /tmp/backup/
while [ $i -gt 0 ];do
    newfile="backupfile"$(expr $i + 1)
    oldfile="backupfile"$i
    mv $oldfile $newfile
    i=`expr $i - 1`
done

if [ -e backupfile ];then
    mv backupfile backupfile1
fi
cd $pwd
cp $1 /tmp/backup/backupfile