一个shell脚本问题请教

Question

v3_addServer.sh内容

cat v3_addServer.sh 
#!/bin/bash
uplist=ipList

main_2()
{
while read noteline
do
        if [ -z "`echo $noteline | grep -v ^$`" ]; then
                continue
        fi

        commentflag=${noteline:0:1}
        if [ "${commentflag}" == "#" ]; then
                continue
        fi


        PlatformId=`printf "$noteline" | awk '{print $1}'`
        ServerId=`printf "$noteline" | awk '{print $2}'`
        ServerIP=`printf "$noteline" | awk '{print $3}'`
        DbIp=`printf "$noteline" | awk '{print $4}'`
                echo $PlatformId $ServerId $ServerIP $DbIp
done<$uplist
}

#主程序
main_2

ipList内容

cat ipList
# 01id  02id      测试1ip           测试2ip
2       1       192.167.33.216  172.31.252.133
2       2       192.167.33.43   172.31.252.134
2       3       192.167.33.164  172.31.252.142
2       4       192.167.33.180  172.31.252.141
2       5       192.167.33.197  172.31.252.140
2       6       192.167.33.106  172.31.252.139
2       7       192.167.33.185  172.31.252.138
2       8       192.167.33.97   172.31.252.136
2       9       192.167.33.187  172.31.252.137

执行sh v3_addServer.sh可以正常打印ipList中的内容

sh v3_addServer.sh 
2 1 192.167.33.216 172.31.252.133
2 2 192.167.33.43 172.31.252.134
2 3 192.167.33.164 172.31.252.142
2 4 192.167.33.180 172.31.252.141
2 5 192.167.33.197 172.31.252.140
2 6 192.167.33.106 172.31.252.139
2 7 192.167.33.185 172.31.252.138
2 8 192.167.33.97 172.31.252.136
2 9 192.167.33.187 172.31.252.137

现在往v3_addServer.sh 中的main_2()添加read,进行读取外部指令的操作：

main_2()
{
while read noteline
do
        if [ -z "`echo $noteline | grep -v ^$`" ]; then
                continue
        fi

        commentflag=${noteline:0:1}
        if [ "${commentflag}" == "#" ]; then
                continue
        fi


        PlatformId=`printf "$noteline" | awk '{print $1}'`
        ServerId=`printf "$noteline" | awk '{print $2}'`
        ServerIP=`printf "$noteline" | awk '{print $3}'`
        DbIp=`printf "$noteline" | awk '{print $4}'`
                echo $PlatformId $ServerId $ServerIP $DbIp
echo  "确认信息:"
read  cmdName
case $cmdName in
       yes|YES)
               #checkStatus
               echo "执行checkStatus函数"
       ;;
       no|NO)
               echo "退出."
       ;;
esac

done<$uplist
}

再次执行v3_addServer.sh

sh v3_addServer.sh  
2 1 192.167.33.216 172.31.252.133
确认信息:
2 3 192.167.33.164 172.31.252.142
确认信息:
2 5 192.167.33.197 172.31.252.140
确认信息:
2 7 192.167.33.185 172.31.252.138
确认信息:
2 9 192.167.33.187 172.31.252.137
确认信息:

没有读取到read cmdName这一行，而且打印出，也只打印了 1 3 5 7 9行的，这是为什么的？

Answer 1

... done<$uplist 这是重定向的意思，把 uplist 文件的内容作为标准输入。
一次循环里有两个read。read意思是从标准输入读取一行，所以
read noteline 读取奇数行
read cmdName读取偶数行。
所以下面这个吧

for line in `cat filename`
do
    echo $line;
done