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期望脚本 su 到 root 并执行 sed

发布于 2024-11-07 11:12:05 字数 202 浏览 2 评论 0原文

我以前从未使用过expect，但需要一个脚本来对大量主机执行以下操作

ssh 到机器
su 到 root 并输入 root 密码
sed /etc/passwd 中的一个文件以将某些文本替换为其他文本，对于这个例子，我们假设原始文本是 TEXT，而替换它的文本是 NEWTEXT

有谁可以帮忙吗？

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抹茶夏天i‖ 2024-11-14 11:12:05

可以理解的是，以 root 身份执行脚本来处理命令是一个巨大的安全问题，通常是不允许的。

然而，Expect 能够运行伪终端，因此它可以像人类打字一样工作远离键盘。

这或多或少是您所要求的，但未经测试。

#!/bin/sh
# if run from shell, restart with wish \
exec wish "$0" "$@"

package require Expect

proc fix_a_host {host usrname password root_password} {
        # open session to host, wait for a username prompt
        spawn ssh $host
        expect "username:"

        # send username, wait for a password prompt
        send "$usrname\r"
        expect "password:"

        # send password, wait for shell prompt
        send "$password\r"
        expect "%"

        # become root, wait for prompt
        send "su\r"
        expect "#"

        # change TEXT to NEWTEXT in password file
        send "sed 's/TEXT/NEWTEXT'" /etc/passwd
        expect "#"

        # exit root, exit host connection
        send "exit\r"
        expect "%"

        send "exit\r"
        expect eof
}       

fix_a_host {"host1" "someuser" "user_password"  "root_password"}
fix_a_host {"host2" "someuser" "user_password"  "root_password"}

如果是我，我会将 sed 命令更改为破坏性较小的命令，例如 grep TEXT /etc/passwd ，直到确信它运行良好为止。对于显示您想要查看的输出的远程命令，请使用

set results $expect_out(buffer)
send "some_command\r"
expect "#"    # use the command prompt to indicate output is complete
puts "command output is got `$buffer`"

Understandably, executing a script to process commands as root is a huge security issue, and is generally not allowed.

However, Expect has the ability to run a pseudo terminal, so it can act just like a human typing away at a keyboard.

This is more or less what you asked, but is untested.

#!/bin/sh
# if run from shell, restart with wish \
exec wish "$0" "$@"

package require Expect

proc fix_a_host {host usrname password root_password} {
        # open session to host, wait for a username prompt
        spawn ssh $host
        expect "username:"

        # send username, wait for a password prompt
        send "$usrname\r"
        expect "password:"

        # send password, wait for shell prompt
        send "$password\r"
        expect "%"

        # become root, wait for prompt
        send "su\r"
        expect "#"

        # change TEXT to NEWTEXT in password file
        send "sed 's/TEXT/NEWTEXT'" /etc/passwd
        expect "#"

        # exit root, exit host connection
        send "exit\r"
        expect "%"

        send "exit\r"
        expect eof
}       

fix_a_host {"host1" "someuser" "user_password"  "root_password"}
fix_a_host {"host2" "someuser" "user_password"  "root_password"}

If it were me, I'd change the sed command to something far less destructive, like grep TEXT /etc/passwd until confident it works well. For a remote command which display output you want to see, use

set results $expect_out(buffer)
send "some_command\r"
expect "#"    # use the command prompt to indicate output is complete
puts "command output is got `$buffer`"

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