Bash 中的 bang 美元 (!$) 是什么？
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What is bang dollar (!$) in Bash?
提问by Snowcrash
Bang dollar seems to refer to the last part of the last command line.
Bang Dollar 似乎指的是最后一个命令行的最后一部分。
E.g.
例如
$ ls -l
.... something
$ !$
-l
bash: -l command not found
I can find plenty on the dollar variables (e.g. $!) but not on this. Any explanation?
我可以在美元变量（例如$!）上找到很多，但在此上找不到。有什么解释吗？
回答by gniourf_gniourf
That's the last argument of the previous command. From the documentation:
这是上一个命令的最后一个参数。从文档：
!!:$designates the last argument of the preceding command. This may be shortened to
!$.
!!:$指定前面命令的最后一个参数。这可以缩短为
!$.
Remark.If you want to play around with Bash's history, I suggest you turn on the shell option histverifylike so:
评论。如果你想玩转 Bash 的历史，我建议你histverify像这样打开 shell 选项：
shopt -s histverify
(you can also put it in your .bashrcto have it on permanently). When using history substitution, the substitution is not executed immediately; instead, it is put in readline's buffer, waiting for you to press enter… or not!
（你也可以把它放在你的身上.bashrc以永久使用它）。使用历史替换时，替换不会立即执行；相反，它被放在 readline 的缓冲区中，等待您按 Enter 键……或者不！
To make things precise, typing !$is not equivalent to typing "$_": !$is really a history substitution,refering to the last word of the previous command that was entered,whereas "$_"is the last argument of the previously executedcommand. You can compare both (I have shopt -s histverify):
准确地说，打字!$不等同于打字"$_"：!$实际上是一个历史替换，指的是输入的上一个命令的最后一个单词，而"$_"是上一个执行命令的最后一个参数。你可以比较两者（我有shopt -s histverify）：
$ { echo zee; }
zee
$ echo "$_"
zee
$ { echo zee; }
zee
$ echo !$
$ echo }
Also:
还：
$ if true; then echo one; else echo two; fi
one
$ echo "$_"
one
$ if true; then echo one; else echo two; fi
$ echo !$
$ echo fi
And also:
并且：
$ echo zee; echo "$_"
zee
zee
$ echo zee2; echo !$
$ echo zee2; echo "$_"
And also
并且
$ echo {1..3}
1 2 3
$ echo "$_"
3
$ echo {1..3}
1 2 3
$ echo !$
$ echo {1..3}
And also
并且
$ echo one ;
$ echo "$_"
one
$ echo one ;
one
$ echo !$
$ echo ;
There are lots of other examples, e.g., with aliases.
还有很多其他的例子，例如，别名。
回答by zee
!$can do what $_does, except the fact that $_does not store the value it returns (as its substitution) to history.
!$可以做什么$_，除了$_不存储它返回的值（作为它的替代）到history.
Here is an example.
这是一个例子。
With !$
和 !$
za:tmep za$ ls -lad
drwxr-xr-x 4 za staff 136 Apr 6 2016 .
za:tmep za$ !$
-lad
-bash: -lad: command not found
za:tmep za$ history | tail -n 3
660 ls -lad
661 -lad <<== history shows !$ substitution.
662 history | tail -n 3
With $_
和 $_
za:tmep za$ ls -lad
drwxr-xr-x 4 za staff 136 Apr 6 2016 .
za:tmep za$ $_
-bash: -lad: command not found
za:tmep za$ history | tail -n 3
663 ls -lad
664 $_ <<== history shows $_ and not its substitution.
665 history | tail -n 3
za:tmep za$
More options:
更多选择：
!^ first argument
!:2 second argument
!:2-$ second to last arguments
!:2* second to last arguments
!:2- second to next to last arguments
!:2-3 second to third arguments
!$ last argument
!* all arguments
回答by Mike D3ViD Tyson
Monkey's answer:
猴子的回答：
whit !$ you can easily print the last wordof the previous command
白衣！美元，你可以轻松打印最后一个字的的前一个命令
#Create new file
touch newfile.txt
#Edit new file using !$ instead newfile.txt again
nano !$
