-bash：！/ usr / bin / env：找不到事件 [英] -bash: !/usr/bin/env: event not found

问题描述

我收到一条奇怪的错误消息，试图将shebang写入python脚本：

I got this strange error message trying to write shebang to a python script:

$ echo "#!/usr/bin/env python" > scripts/sandbox.py 
-bash: !/usr/bin/env: event not found

$ echo "say what?" > scripts/sandbox.py

立即执行相同的操作，但不使用shebang行。这是什么行为，如何克服？谢谢

Immediately, doing the same thing but without using shebang line works. What is this behavior and how can it be overcome? thank you

推荐答案

！是bash的特殊字符，它是用于引用先前的命令。它在双引号内扩展。
为避免这种情况，请用单引号引起来：

! is a special character to bash, it is used to refer to previous commands. It is expanded within double-quotes. To avoid that, enclose them in single-quotes instead:

echo '#!/usr/bin/env python' > scripts/sandbox.py 

@ mklement0 在一条评论中对其进行了精美的说明：

@mklement0 clarified it beautifully in a comment:

更具体地说，是！是Bash的历史记录扩展功能的特殊功能，该功能默认情况下（仅）在交互式shell中处于启用状态。除了通过使用单引号引起来的字符串来避免它外，还可以与 set + H

More specifically, ! is special to Bash's history expansion feature, which is on by default (only) in interactive shells. In addition to avoiding it by using single-quoted strings, it can be turned off altogether with set +H

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