ping, telnet的shell脚本问题

gdxnfx

参照论坛里面的文章，改写成了如下自动telnet路由器的脚本。请教下大家，如何才能实现，ping $ipaddress能通的时候才执行telnet及以下的命令呢？

#!/usr/bin/expect -f

set ipaddress [lindex $argv 0]

set password [lindex $argv 1]

set enable [lindex $argv 2]

set tftpaddress [lindex $argv 3]


spawn telnet $ipaddress
  
expect "*Password:*"
send "$password\n"
expect "*>*"
send "en\n"
expect "*Password:*"
send "$enable\n"
expect "*#*"
send "show clock\n"
expect "*#*"
send "copy run tftp\n"
expect "*[]?*"
send "$tftpaddress\n"
expect "*]?*"
send "\n"
expect "#"
send "exit\n\n"

expect eof