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Expect是一个免费的编程工具语言，用来实现自动和交互式任务进行通信，而无需人的干预。
使用前需要先安装expect的rpm包，centos6.5 64位上的版本是expect-5.44.1.15-5.el6_4.x86_64
另外，可扩容是建立在/是逻辑卷的前提下：
通过df -h查看磁盘信息，例如：
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-LogVol01 35G 9.3G 24G 29% /
tmpfs 7.8G 0 7.8G 0% /dev/shm
/dev/sda1 194M 34M 150M 19% /boot
再通过lvdisplay查看逻辑卷信息：
--- Logical volume ---
LV Path /dev/VolGroup/LogVol01
LV Name LogVol01
VG Name VolGroup
LV UUID cxD3nz-8GOa-pye4-sHYn-78yn-sCbK-OQcVCZ
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2015-03-27 08:16:39 +0800
LV Status available
# open 1
LV Size 35.05 GiB
Current LE 8974
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Path /dev/VolGroup/LogVol00
LV Name LogVol00
VG Name VolGroup
LV UUID tp3pqG-VW3I-rVnD-WvZ3-MwS0-caIf-LmpeCl
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2015-03-27 08:16:50 +0800
LV Status available
# open 1
LV Size 2.00 GiB
Current LE 512
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
可以看到/所在逻辑卷是/dev/mapper/VolGroup-LogVol01，磁盘容量是35.05G。
假设新增的磁盘是sdb、此前系统中已经存在2个分区，以下脚本将完成分区动作，新创建的分区为sdb1：
#!/usr/bin/expect spawn fdisk /dev/sdb expect "):" send "n\n" expect "4)" send "p\n" expect ":" send "1\n" expect ":" send "\n" expect ":" send "\n" expect "):" send "p\n" expect "):" send "w\n" expect eof exit END
上述脚本执行完成后，可能需要重启系统生效。
接下来是将sdb1划入/
#!/usr/bin/expect
set timeout 3600
spawn mkfs.ext4 /dev/sdb1
expect ‘override‘
sleep 5
spawn pvcreate /dev/sda3
expect ‘successfully created‘
sleep 5
spawn vgextend VolGroup /dev/sda3
expect ‘successfully extended‘
sleep 5
spawn fdisk -l /dev/sda3
set accum {}
expect {
{:*GB} {
set accum "${accum}$expect_out(0,string)"
}
}
puts "\n"
puts "###########################################"
puts "###### sda3 has $accum free space ######"
puts "###########################################"
puts "\n"
puts "Please Type the Percentage of free space (1 to 100，defaul 100), then Type ENTER:"
puts "请输入100以内的正整数，将sda3可用磁盘空间按百分比 新增给 / 使用，并以回车结束。直接回车则默认为100%："
expect_user "\n" {
set raw $expect_out(buffer)
# remove final carriage return
set response [string trimright "$raw" "\n%"]
}
if {$response==""} {set response 100}
puts "$response"
spawn lvextend -l +$response%FREE /dev/mapper/VolGroup-LogVol01
expect ‘successfully resized‘
sleep 5
spawn resize2fs /dev/mapper/VolGroup-LogVol01
expect ‘blocks long‘
#set timeout 5
puts "Resize Complete!"
exit
END
上述脚本会让你输入一个数字，决定将新增磁盘多少百分比的空间扩容至/中，直接回车默认为100%。
附：expect_out用法
expect -re ".*" {}
会自动清空expect_out缓存内的内容
expect_out(buffer)输入的所有内容
expect_out(0,string)与输入内容相匹配的部分
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原文地址：http://my.oschina.net/erichd/blog/500134
