Expect脚本中向cat发送EOF无效的解决方法（Cygwin环境）

我需要在Expect脚本里向cat命令输入内容，之后通知它到达EOF，但尝试用send \004发送EOF控制序列时完全无效，导致脚本超时。

初始脚本 #

#!/usr/bin/expect

spawn bash -c "echo READY; foo=\$(cat); echo DONE"
expect "READY\r\n"
send -- "Hello\n"

# 此操作无效
send \004

# 此处会超时
expect "DONE\r\n"

调试输出（执行expect -d test.exp） #

$ expect -d test.exp
expect version 5.45
argv[0] = expect  argv[1] = -d  argv[2] = test.exp
set argc 0
set argv0 "test.exp"
set argv ""
executing commands from command file test.exp
spawn bash -c echo READY; foo=$(cat); echo DONE
parent: waiting for sync byte
parent: telling child to go ahead
parent: now unsynchronized from child
spawn: returns {36656}

expect: does "" (spawn_id exp4) match glob pattern "READY\r\n"? no
READY

expect: does "READY\r\n" (spawn_id exp4) match glob pattern "READY\r\n"? yes
expect: set expect_out(0,string) "READY\r\n"
expect: set expect_out(spawn_id) "exp4"
expect: set expect_out(buffer) "READY\r\n"
send: sending "Hello\n" to { exp4 }
send: sending "\u0004" to { exp4 }

expect: does "" (spawn_id exp4) match glob pattern "DONE\r\n"? no
Hello

expect: does "Hello\r\n" (spawn_id exp4) match glob pattern "DONE\r\n"? no
expect: timed out

解决方案 #

这个问题是Cygwin环境特有的，只需在send -- "Hello\n"之后添加sleep 1即可解决：

#!/usr/bin/expect

spawn bash -c "echo READY; foo=\$(cat); echo DONE"
expect "READY\r\n"
send -- "Hello\n"
sleep 1

# 若无前置sleep 1，此操作在Cygwin中无效
send \004
expect "DONE\r\n"
exit

内容的提问来源于stack exchange，提问作者Alexey Semenyuk