[英]Get one line of user input and then execute it as Bash commands
我寫了一個期望腳本,有助於在遠程機器上執行命令。 執行完成后,我想獲取一行用戶輸入,然后將其發送到遠程 bash,這是代碼片段:
#! /usr/bin/env expect
...
spawn ssh -l $user $host
...
send_tty -- "Enter your command: "
set timeout -1
# match only printable characters (prevent from pressing TAB)
expect_tty eof exit -re {([[:print:]]*)\n}
send_tty -- "\n"
set timeout 10
# send the command to remote shell
send "$expect_out(1,string)"
expect "$GENERAL_PROMPT"
但是,如果輸入類似於: ls /"
,我的程序將被阻止,因為遠程shell希望通過提示字符串 "> " 來獲取更多字符。實際上,我希望 bash 不會提示更多輸入,而不僅僅是打印錯誤信息:
$ read COMMAND
ls /"
$ eval "$COMMAND"
bash: unexpected EOF while looking for matching `"'
bash: syntax error: unexpected end of file
我可以在我的腳本中實現這一點嗎?
#!/usr/bin/expect
set prompt "#|%|>|\\\$ $"; # A generalized prompt to match known prompts.
spawn ssh -l dinesh xxx.xx.xx.xxx
expect {
"(yes/no)" { send "yes\r";exp_continue}
"password"
}
send "mypassword\r"
expect -re $prompt
send_tty -- "Enter your command: "
set timeout -1
# match only printable characters (prevent from pressing TAB)
expect_tty eof exit -re {([[:print:]]*)\n}
send_tty -- "\n"
set timeout 10
puts "\nUSER INPUT : $expect_out(1,string)"
# send the command to remote shell
# Using 'here-doc', to handle possible user inputs, instead of quoting it with any other symbol like single quotes or backticks
send "read COMMAND <<END\r"
expect -re $prompt
send "$expect_out(1,string)\r"
expect -re $prompt
send "END\r"
expect -re $prompt
# Since we want to send the literal dollar sign, I am sending it within braces
send {eval $COMMAND}
# Now sending 'Return' key
send "\r"
expect -re $prompt
為什么使用“here-doc”?
如果我使用反引號或單引號來轉義命令,那么如果用戶在命令本身中使用反引號或單引號,則它可能會失敗。 所以,為了克服這個問題,我添加了 here-doc。
輸出 :
dinesh@MyPC:~/stackoverflow$ ./zhujs
spawn ssh -l dinesh xxx.xx.xx.xxx
dinesh@xxx.xx.xx.xxx's password:
[dinesh@lab ~]$ matched_literal_dollar_sign
Enter your command: ls /"
USER INPUT : ls /"
read COMMAND <<END
> ls /"
> END
[dinesh@lab ~]$ eval $COMMAND
-bash: unexpected EOF while looking for matching `"'
-bash: syntax error: unexpected end of file
[dinesh@lab ~]$ dinesh@MyPC:~/stackoverflow$
更新 :
使用here-doc
主要原因是它使讀取充當非阻塞命令。 即我們可以快速進行下一個命令。 否則,我們必須等到Expect
超時。 (當然,我們可以動態更改超時值。)
這只是一種方法。 您可以根據需要更改它,只需使用read
命令即可。
我認為這將是一個很好的interact
案例——期望讓步並讓用戶直接與生成的程序交互。
spawn ssh -l $user $host
#...
send_user "You are now about to take control: type QQQ to return control to the program\n"
interact {
QQQ return
}
send_user "Thanks, I'm back in charge ...\n"
這是一個單行版本
read > export cmd ; eval $cmd ; unset cmd
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