在 expect 脚本中，grep 的输出未保存在 expect_out(buffer) 中

Question

我有一个脚本可以根据某个值对文件进行 grep，但是 grep 的响应没有保存在 expect_out（缓冲区）中。下面是我的代码：

#!/usr/bin/expect 

set prompt "(%|>|#|\$)"
#set prompt "(%|>|\$)"

set pidBash [ spawn bash ]
puts "\nStarting script....."

send -- "\n"
expect -re $prompt {}
set output $expect_out(buffer)
send -- "grep '^option' /home/pb791b/udhcpd.conf | grep lease\n"
sleep 4
expect -re $prompt {}

set output $expect_out(buffer)
set outputLines [split $output "\n"]
set len [llength $outputLines]
puts "\nlen: $len\n"
for {set i 0} {$i<[expr $len]} {incr i} {
    set line [lindex $outputLines $i]
    puts "line $i: $line"
}

exec kill $pidBash
puts "\nprocess Bash terminated"

puts "End script."

下面是我的输出：

pb791b@pb791b-VirtualBox:~/devtest/ngs/base/Tests/shellScripts$ ./temp2.sh 
spawn bash

Starting script.....

pb791b@pb791b-VirtualBox:~/devtest/ngs/base/Tests/shellScripts$ 
grep '^option' /home/pb791b/udhcpd.conf | grep lease
pb791b@pb791b-VirtualBox:~/devtest/ngs/base/Tests/shellScripts$ grep '^option' /home/pb791b/udhcpd.conf | grep lease
option  lease   864000      # 10 days of seconds
pb791b@pb791b-VirtualBox:~/devtest/ngs/base/Tests/shellScripts$ 
len: 3

line 0:  
line 1: grep '^option' /home/pb791b/udhcpd.conf | grep lease
line 2: pb791b@pb791b-VirtualBox:~/devtest/ngs/base/Tests/shellScripts$

process Bash terminated
End temp.sh script.
pb791b@pb791b-VirtualBox:~/devtest/ngs/base/Tests/shellScripts$

当我打印 expect_out(buffer) 时，它会打印 grep 命令，然后是提示，但缺少 grep "option lease 864000 # 10 days of seconds"

的输出

Answer 1

删除 send -- "\n" 它应该可以工作：

set pidBash [ spawn bash ]
puts "\nStarting script....."

#send -- "\n"
expect -re $prompt {}

在发送 grep 命令之前，使用 send -- "\n" 你应该期待两次提示（当你登录时你会看到第一个提示，然后你按 \n 你会看到第二个提示） :

set pidBash [ spawn bash ]
puts "\nStarting script....."

send -- "\n"
expect -re $prompt {}
expect -re $prompt {}

在 expect 脚本中，grep 的输出未保存在 expect_out(buffer) 中

In expect script, output of grep is not saved in expect_out(buffer)

bash

expect