使用expect实现fdisk /dev/sdb 免交互创建分区，要求一次性创建一个20G/dev/sdb1的普通分区和一个4G/dev/sdb的swap分区和一个逻辑分区10G /dev/sdb5

可以使用expect脚本实现免交互创建分区，具体实现如下：

#!/usr/bin/expect

set timeout 5

spawn fdisk /dev/sdb

expect "Command (m for help):"

send "n\r"

expect "Select (default p):"

send "p\r"

expect "Partition number (2-4, default 2):"

send "1\r"

expect "First sector (2048-41943039, default 2048):"

send "\r"

expect "Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-41943039, default 41943039):"

send "+20G\r"

expect "Command (m for help):"

send "n\r"

expect "Select (default p):"

send "p\r"

expect "Partition number (2-4, default 2):"

send "2\r"

expect "First sector (41943040-41943039, default 41943040):"

send "\r"

expect "Last sector, +/-sectors or +/-size{K,M,G,T,P} (41943040-41943039, default 41943039):"

send "+4G\r"

expect "Command (m for help):"

send "n\r"

expect "Select (default p):"

send "e\r"

expect "Partition number (2-4, default 2):"

send "\r"

expect "First sector (8392704-41943039, default 8392704):"

send "\r"

expect "Last sector, +/-sectors or +/-size{K,M,G,T,P} (8392704-41943039, default 41943039):"

send "+10G\r"

expect "Command (m for help):"

send "t\r"

expect "Partition number (1-5):"

send "2\r"

expect "Hex code (type L to list all codes):"

send "82\r"

expect "Command (m for help):"

send "w\r"

expect eof

脚本中，使用spawn命令启动fdisk命令，并使用expect命令匹配fdisk命令的交互提示，并发送对应的输入，以达到自动创建分区的目的。其中，"+20G"、"+4G"和"+10G"分别表示创建20G、4G和10G大小的分区。最后，使用expect命令匹配fdisk命令的结束符，结束交互。