这个shell脚本的用处是读出url.txt的内容，url.txt内容类似于

http://www.mydomain.com/some_directory/1.html
http://www.mydomain.com/some_directory/2.html
http://www.mydomain.com/some_directory/3.html
http://www.mydomain.com/some_directory/4.html

然后把文件内容逐行读出的转化成本地路径，先备份打包，然后一起删除。

#!/bin/bash 
# 
# use "sed" to change url to local path. separator is ";". 
# 
sed -e 's;http://www.mydomain.com/some_directory/;;g' url.txt >temp 
#
# loop. compress all files into a .tar file. 
#
files=$(cat temp) 
for file in $files 
do 
        tar -rf url_backup_`date +%Y%m%d%H`.tar  $file 
        rm -rf $file 
        echo $file 
done 
# end loop and delete the temporary file. 
rm -rf temp