$ _和！$之间的区别

Question

如果这是重复的话，我感到非常抱歉。这是我在搜索谷歌时确定的一点点​​成功：

https://www.google.com/search?q=difference+between+%24_+and+!%24

我能想到的最好的结果是，!$是首选，可以让您的工作在命令历史记录和shell输出中更加明显。

实施例

02:05 Mac Shell: ~/>$ cat $_
this is a file called something
02:06 Mac Shell: ~/>$ cat !$
cat $_
this is a file called something
02:06 Mac Shell: ~/>$ cat something
this is a file called something
02:06 Mac Shell: ~/>$ cat !$
cat something
this is a file called something
02:06 Mac Shell: ~/>$ echo "This is a string"
This is a string
02:08 Mac Shell: ~/>$ echo !$
echo "This is a string"
This is a string
02:08 Mac Shell: ~/>$ echo "This is a string"
This is a string
02:08 Mac Shell: ~/>$ echo $_
This is a string
02:08 Mac Shell: ~/>$ history | tail
  857  30/12/16 02:05:55 vim something
  858  30/12/16 02:06:07 cat $_
  859  30/12/16 02:06:12 cat $_
  860  30/12/16 02:06:36 cat something
  861  30/12/16 02:06:40 cat something
  862  30/12/16 02:08:18 echo "This is a string"
  863  30/12/16 02:08:26 echo "This is a string"
  864  30/12/16 02:08:32 echo "This is a string"
  865  30/12/16 02:08:37 echo $_
  866  30/12/16 02:09:14 history | tail
02:09 Mac Shell: ~/>$

问题：

我还应该了解其他差异吗？

编辑：

antak引起我的注意，$ _对于一个衬垫来说非常好，而！$则不是：

02:35 Mac Shell: ~/>$ echo bar && echo foo$_
bar
foobar
02:35 Mac Shell: ~/>$ echo bar && echo foo!$
echo bar && echo foofoo$_
bar
foofoobar
02:35 Mac Shell: ~/>$