利用shell脚本函数实现网络连通性的检测
通常情况下，linux系统网络连通性的检测有两种方法：
1、通过“ping指令 + 目标IP” 或者 “ping指令 + 目标IP域名”
注意针对IPv6地址的IP网络检测需要试用ping6，同时ping6中不能使用参数hops，因为IP6源码中已经舍弃了路由，见如下英文解释：
SYNOPSIS
ping [-aAbBdDfhLnOqrRUvV] [-c count] [-F flowlabel] [-i interval] [-I interface] [-l preload] [-m mark] [-M pmtudisc_option] [-N nodeinfo_option]
[-w deadline] [-W timeout] [-p pattern] [-Q tos] [-s packetsize] [-S sndbuf] [-t ttl] [-T timestamp option] [hop ...] destinationt.
Notes:
ping6 is IPv6 version of ping, and can also send Node Information Queries (RFC4620). Intermediate hops may not be allowed, because IPv6 source
routing was deprecated.
ping指令调用时的常用参数：
# Parameter:
# -c the number of packages to send
# -i internel between two packages
# -W timeout seconds
# Check the connect status of internet
function check_ip_status()
{
ping -c 3 -i 0.2 -W 3 $1 &> /dev/null
if [ $? -eq 0 ];then
return 0
else
return -1
fi
}
if ( `$(check_ip_status 10.74.120.104) -ne 0` );then
echo "cannot connect guestconf server:10.74.120.104"
exit -1
fi
2、使用“curl指令 + IP域名”
#!/usr/bin/bash
#
#检测网络链接&&ftp上传数据
function networkAndFtp()
{
#超时时间
timeout=5
#目标域名
target=www.baidu.com
#获取响应状态码
ret_code=`curl -I -s --connect-timeout $timeout $target -w %{http_code} | tail -n1`
if [ "x$ret_code" = "x200" ]; then
#网络畅通
else
#网络不畅通
fi
}