十、expect 自动交互

expect 内部命令

语法结构

spawn   shell 命令程序 

expect   "捕获到shell 命令程序执行之后输出的字符串"  
send  "发送给 shell 命令程序的字符串"

在命令行直接输入 expect 可以进入 expect 程序的解释器终端

[root@e5ac44e88027 ~]# expect
expect1.1> spawn echo "hello"   # 发送一条 shell 命令， 这里是指 echo "hello"
spawn echo hello
1490
expect1.2> expect "hello"     # 捕获这个字符串，只要包含这个字符串就可以
hello
expect1.3> send "yes\n"      # 发送一个字符串
expect1.4> expect off           # 结束这次捕获
yes
expect1.5>

在脚本中使用

# 开始 expect  解释器程序
/usr/bin/expect<<EOF

# 设置捕获字符串后，期待回复的超时时间
set timeout 30

spawn   ssh-keygen

# 开始进连续捕获
expect     {
        ".ssh/id_rsa)"       { send    "\n";  exp_continue }
        "Overwrite (y/n)?"   { send    "y\n"; exp_continue }
        "no passphrase):"    { send    "\n";  exp_continue }
        "again:"             { send    "\n";  exp_continue }
}

# 结束 expect 解释器程序
EOF

".ssh/id_rsa)" { send "\n"; exp_continue }
意思是 捕获到字符串 ".ssh/id_rsa)" 后 发送字符串 "\n" 就是相当于按下回车键
exp_continue 意思是继续进行捕获，不退出 expect 程序

实战案例

# 写个用于自动生成密钥对的函数
auto_keygen (){
    /usr/bin/expect<<EOF

    set timeout 30

    spawn   ssh-keygen

    expect     {

        ".ssh/id_rsa)"       { send    "\n";  exp_continue }
        "Overwrite (y/n)?"   { send    "y\n"; exp_continue }
        "no passphrase):"    { send    "\n";  exp_continue }
        "again:"             { send    "\n";  exp_continue }
    }

EOF
}

# 写个自动免密登录的函数
send_key () {
pwd=upsa
/usr/bin/expect <<EOF
set timeout 30

# 发送公钥给对方服务器
spawn ssh-copy-id root@$1
expect {
"yes/no" { send "yes\n"; exp_continue }
"password:" { send "${pwd}\n"} }
expect eof
EOF
}

# 定义一个变量，其值是当前用户的公钥文件
pub_key_file=$HOME/.ssh/id_rsa.pub

# 假如公钥文件不存在，说明需要创建密钥对
if [ ! -f ${pub_key_file} ];then
    auto_keygen
fi

# 循环一个存放 ip 地址的文件，并且把每个 IP地址传递给 函数
for ip in $(cat ./ips.txt)
do
   send_key $ip
done

keygen (){
    /usr/bin/expect<<EOF
    spawn ssh-keygen

        expect {
            "(/root/.ssh/id_rsa):"       { send "\n"; exp_continue }
            "Overwrite (y/n)?"           { send "y\n"; exp_continue }
            "(empty for no passphrase):" { send "\n"; exp_continue }
            "passphrase again:"          { send "\n" exp_continue }
        }
EOF
}

copyid (){
passwd=密码
/usr/bin/expect<<EOF
    spawn ssh-copy-id root@$ip
    expect {
        "continue connecting (yes/no)?" {send "yes\n" exp_continue }
        "password:"                     { send "$passwd\n" exp_continue }
    }
EOF
}
    idfile=$HOME/.ssh/id_rsa.pub
    if [ -f $idfile ];then
        exit
    else
        keygen
    fi
for ip in 10.3.134.{2..254}     #多主机进行交互免密登陆
do
    copyid $ip
done