为什么Scala会忽略命令行参数中的感叹号? [英] Why does Scala ignore exclamation points in command line arguments?
问题描述
如果我编写的Scala脚本(或App)仅打印出命令行参数,我会注意到它会忽略所有的‘!’字符。例如,如果我的脚本如下所示:
If I write a Scala script (or App) that just prints out the command line arguments, I notice that it ignores all the '!' characters. For example, if my script looks like:
println(args(0))
然后运行:
scala MyScript "Hello!"
我得到输出:
Hello
如果我用以下命令运行它:
And if I run it with:
scala MyScript "Hello! World!"
我也得到:
Hello
这是怎么回事?的目的是什么!
What's going on? What is the purpose of the ! character in arguments that causes this behaviour?
推荐答案
!
是历史替换吗? 。
在尝试
退出浏览器,就像引用一样运行。 scala MyScript hello!
!
Try scala MyScript hello!
with !
at EOL to see it work as if quoted.
http://www.gnu.org/software/bash/manual/bashref.html#Event-Designators
http://www.gnu.org/software/bash/ manual / bashref.html#Single-Quotes
在Windows上, scala.bat
命令脚本已启用延迟扩展。
On windows, the "scala.bat"
command script has delayed expansion enabled.
http:/ /en.wikibooks.org/wiki/Windows_Batch_Scripting
http://en.wikibooks .org / wiki / Windows_Batch_Scripting#SETLOCAL
http://zh.wikibooks.org/wiki/Windows_Batch_Scripting#Command-line_arguments
禁用对<$ c $的解释c>!myvar!:
C:\Users\you> scala greeting.script "hello^!"
hello!
C:\Users\you> set world= Bob
C:\Users\you> scala greeting.script "hello!world!"
hello Bob
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