January 2021
Intermediate to advanced
581 pages
15h 7m
Chinese
Content preview from bash shell脚本编程经典实例 （第2版）
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编写安全的
shell
脚本
｜
309
极大地减少了输入口令的次数。有了
keychain
，在本地主机每次重启时输入口令
即可。
keychain
还使得远程
cron
作业能够轻松安全地“挂接”（
hook in
）在长期运行的
ssh-agent
进程上，这样就允许脚本利用基于密钥的登录（
key-based login
）。
shell
脚本
keychain
不仅精巧、质量上乘，而且注释详尽，先前我们讨论过的那些将环境
变量导到其他会话的烦琐过程，都可以通过
keychain
实现自动化并进行管理。而且还能
使其为脚本和
cron
所用。但你可能会自问：先等一下，你想让我把自己所有的密钥交给
keychain
，直到重启主机为止？没错，不过这并没有听起来那么糟糕。
首先，你随时都能终止
keychain
，不过这也使得脚本或
cron
无法再使用它。其次，
--clear
选项可以在你登录时冲洗掉已缓存的密钥。听起来怎么又倒退了？其实这么做是
有道理的。
keychain
的作者给出了详细的解释（首发于
IBM developerWorks
）。
我解释过使用未经加密的私钥是一种危险的做法，因为这会使得别人盗取你的私
钥，无须输入密码就能用它从任何系统登入你的远程账户。好吧，虽然
keychain
不易受到这种滥用的影响（只要坚持使用加密过的私钥），但存在一个可能会被
利用的弱点，这直接与以下事实相关：
keychain
使其很容易“挂接”到长期运行
的
ssh-agent
进程。我在想，要是入侵者能够通过某种途径得到我的密码或口令
来登录本地系统，那会怎么样？如果他们以我的身份登录 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.