expect是Unix系统中用来进行自动化控制和测试的软件工具，应用在交互式软件中如telnet，ftp，Passwd，fsck，rlogin，tip，ssh等等。
用法
Linux中我们经常写脚本处理一些繁琐的任务，但不幸的是很多交互式的命令我们不得不人肉响应。
expect可以代替我们实现与系统的交互。
我们可以通过expect实现远程自动更改用户密码，而不需要手动输入旧密码和新密码:
#!/bin/bash usr_passwd='old_passwd' new_passwd='new_passwd' while read ip do /usr/bin/expect <<-EOF set timeout -1 spawn ssh -t mina.xiang@$ip expect { "*yes/no*" { send "yes ";exp_continue } "*assword:" { send "$usr_passwd " } } expect "*~]$*" { send "hostname " } expect "*~]$*" { send "passwd " } expect "(current)*password:" { send "$usr_passwd " } expect "New password:" { send "$new_passwd " } expect "Retype*password:" { send "$new_passwd " } expect "*~]$*" { send "exit " } expect eof EOF done < /home/mina.xiang/serverip.txt
最近做得稍微复杂一点的，普通用户卸载软驱floppy模块，普通用户权限不够时需要通过sudo执行。
#!/bin/bash usr_passwd='passwd' while read ip do /usr/bin/expect <<-EOF set timeout -1 spawn ssh -t mina.xiang@$ip expect { "*yes/no*" { send "yes ";exp_continue } "*assword:" { send "$usr_passwd " } } expect "*~]$*" { send "hostname " } expect "*~]$*" { send "tty " } expect "*~]$*" { send "pwd " } expect "*~]$*" { send "sudo modprobe -r floppy " } expect "[sudo]*mina.xiang:" { send "$usr_passwd " } expect "*~]$*" { send "sudo bash -c "echo 'blacklist floppy' >> /etc/modprobe.d/blacklist-floppy.conf" " } expect "*~]$*" { send "sudo bash -c "echo 'install floppy /bin/false' >> /etc/modprobe.d/blacklist-floppy.conf" " } expect "*~]$*" { send "sudo cp /boot/initramfs-3.10.0-693.17.1.el7.x86_64.img /boot/initramfs-3.10.0-693.17.1.el7.x86_64.img.$(date +%m-%d-%H%M%S).bak " } expect "*~]$*" { send "sudo dracut --omit-drivers floppy -f " } expect "*~]$*" { send "sudo sed -i '/^GRUB_CMDLINE_LINUX=/s/"$/ floppy.blacklist=1 rd.driver.blacklist=floppy"/' /etc/sysconfig/grub " } expect "*~]$*" { send "sudo grub2-mkconfig -o /boot/grub2/grub.cfg " } expect "*~]$*" { send "sudo cp /boot/initramfs-3.10.0-693.17.1.el7.x86_64kdump.img /boot/initramfs-3.10.0-693.17.1.el7.x86_64kdump.img.$(date +%m-%d-%H%M%S).bak " } expect "*~]$*" { send "sudo sed -i '/^KDUMP_COMMANDLINE_APPEND=/s/"$/ rd.driver.blacklist=floppy"/' /etc/sysconfig/kdump " } expect "*~]$*" { send "sudo kdumpctl restart " } expect "*~]$*" { send "sudo mkdumprd -f /boot/initramfs-3.10.0-693.17.1.el7.x86_64kdump.img " } expect "*~]$*" { send "exit " } expect eof EOF done < /home/mina.xiang/serverip.txt
--脚本中调用得serverip.txt文件内存放目标机器ip地址，每行一个ip
常用指令
进入expect环境后主要使用的内部命令有三个
- spawn
创建一个新进程，并运行给定的程序，它的主要功能是给运行进程加个壳，用来传递交互指令，expect可以通过spawn监听进程的输出。
- expect
此expect非彼expect，它是expect的内部命令，在expect环境中使用，它用来匹配spawn中进程输出，匹配上了就执行后面的body部分。
- send
用于执行交互动作，改密码时可以send密码，与手工输入密码的动作等效。
expect内部命令会等待目标进程的输出，等待时间默认10秒，没有得到期望值且等待超时后执行下一条命令，也可通过"set timeout number"手动设置时长，“set timeout -1”为永不超时。
expect eof是在等待结束标志。由spawn启动的命令在结束时会产生一个eof标记，expect eof即在等待这个标记.