混合期望和 BASH

Question

我已经编写了一个小的 Expect 脚本来登录 Cisco 设备；登录后，我想重复运行命令并grep 输出。

#!/usr/bin/expect

send_user "Device name: "
expect_user -re "(.*)\n"
set host $expect_out(1,string)

send_user "Username: "
expect_user -re "(.*)\n"
set user $expect_out(1,string)

stty -echo
send_user -- "Password: "
expect_user -re "(.*)\n"
set pass $expect_out(1,string)
stty echo

send_user "show int "
expect_user  -re "(.*)\n"
set intf $expect_out(1,string)
send_user "\n"

spawn telnet $host
expect "Username:"
send "$user\r"
expect "Password:"
send "$pass\r"
expect ">"

此时我们已经登录到设备，我想重复执行命令“show int xxx”并grep特定行的输出。 grep 不在 Expect 中，也没有像 sleep 这样的命令，所以我可以循环执行 show int 命令，grepping 在我的特定行之外。我怎样才能像这样混合 Expect 和 Bash？

更新：我现在已经完成了相当多的脚本，一旦我克服了最后一个障碍，我会发布完整的脚本。一行set bytesnow [exec grep "packets input" \< showint | cut -d \ -f 9] 抛出错误；

child process exited abnormally
   while executing
"exec grep "packets input" < \showint | cut -d \  -f 9"

但它在我编写的测试脚本中运行良好。文件 ./showint 在那里，在命令行上运行该命令可以正常工作吗？我不知道出了什么问题？

更新：更多调查 (http://wiki.tcl.tk/8489) 显示 grep 以状态码 1 退出，这意味着没有找到模式匹配，把该命令在命令行中可以正常工作吗？即使使用 /full/path/to/showint。

END：我意识到自己曾经是个傻瓜，从而纠正了我的错误，答案如下。感谢大家的帮助：D

Answer 1

这就是我要做的

log_user 0
while(1) {
  send -- "sh int $intf | i packets input\r"
  set timeout 5
  expect {
    -re "^ +(\d+) packets" { send_user -- "$expect_out(1,string)" }
    timeout { send_user "broke?\n" }
  }
}

这将为您提供输入的数据包数量。

Answer 2

这是我的第一个 Expect 脚本，其目的是提供接口的实时（几乎 1 秒！）吞吐量。下面的例子给出了一个接口输入速度，因为我们grep 用于包含“数据包输入”的行。将其更改为“数据包输出”以获得该接口的实时输出速率。

#!/usr/bin/expect

# Long delay for those tricky hostnames

set timeout 60

# Prompt user for device name/IP, username, password, 
# and interface to query (gi0/2)

send_user "Device name: "
expect_user -re "(.*)\n"
set host $expect_out(1,string)

send_user "Username: "
expect_user -re "(.*)\n"
set user $expect_out(1,string)

stty -echo
send_user "Password: "
expect_user -re "(.*)\n"
set pass $expect_out(1,string)
send_user "\n"
stty echo

send_user "show int "
expect_user  -re "(.*)\n"
set intf $expect_out(1,string)
send_user "\n"

spawn telnet $host
expect "Username:"
send "$user\r"
expect "Password:"
send "$pass\r"
expect ">"

set byteslast 0
set bytesnow 0

log_user 0

# Enter a continuous loop grabbing the number of bytes that
# have passed through an interface, each second.
# The different in this number each cycle, is essentially
# how much traffic this interface is pushing.

while { true } {
  send "show int $intf\r"
  expect ">"

  set showint [open "showint" "w"]
  puts $showint $expect_out(buffer)
  close $showint

  set bytesnow [exec grep "packets input" \< showint | cut -d \  -f 9]

  if { $bytesnow > $byteslast } {
    set diff [expr $bytesnow - $byteslast]
    set bps [exec expr "$diff" \* 8]
    set kbps [exec expr "$bps" \/ 1000]
  } elseif { $bytesnow < $byteslast } {
    set diff [expr $byteslast - $bytesnow]
    set bps [exec expr "$diff" \* 8]
    set kbps [exec expr "$bps" \/ 1000]
  } elseif { $bytesnow == $byteslast } {
    set kbps 0
  }

  set byteslast $bytesnow
  puts "$kbps Kbps\r"

  sleep 1
}

由于这是我的第一个 Expect 脚本，我毫不怀疑它可以更高效、更清晰地编写（我发现总是如此），所以如果有人对此有任何指示，我会全力以赴！ :)

我的exec grep 命令的问题原来是在此之前，我打开的文件“showint”，我没有关闭，我试图访问另一个文件；小学生的错误！