批处理编程中 %~2 和 %2 的区别？

Question

我正在学习批处理编程，我无法从字面上区分 %~2 和 %2 。另外请举个例子。

Answer 1

%2 替换第二个参数。 %~2 替换了第二个参数，但删除了所有引号：

C:\Temp>type t.cmd
@echo off
echo %%2 is: %2
echo %%~2 is: %~2

C:\Temp>t.cmd first second third
%2 is: second
%~2 is: second

C:\Temp>t.cmd first "second third"
%2 is: "second third"
%~2 is: second third

在命令提示符下，键入help for 以查找扩展变量时的选项（即使不在for 命令中也能正常工作）：

In addition, substitution of FOR variable references has been enhanced.
You can now use the following optional syntax:

    %~I         - expands %I removing any surrounding quotes (")
    %~fI        - expands %I to a fully qualified path name
    %~dI        - expands %I to a drive letter only
    %~pI        - expands %I to a path only
    %~nI        - expands %I to a file name only
    %~xI        - expands %I to a file extension only
    %~sI        - expanded path contains short names only
    %~aI        - expands %I to file attributes of file
    %~tI        - expands %I to date/time of file
    %~zI        - expands %I to size of file
    %~$PATH:I   - searches the directories listed in the PATH
                   environment variable and expands %I to the
                   fully qualified name of the first one found.
                   If the environment variable name is not
                   defined or the file is not found by the
                   search, then this modifier expands to the
                   empty string

The modifiers can be combined to get compound results:

    %~dpI       - expands %I to a drive letter and path only
    %~nxI       - expands %I to a file name and extension only
    %~fsI       - expands %I to a full path name with short names only
    %~dp$PATH:I - searches the directories listed in the PATH
                   environment variable for %I and expands to the
                   drive letter and path of the first one found.
    %~ftzaI     - expands %I to a DIR like output line

In the above examples %I and PATH can be replaced by other valid
values.  The %~ syntax is terminated by a valid FOR variable name.
Picking upper case variable names like %I makes it more readable and
avoids confusion with the modifiers, which are not case sensitive.

Answer 2

嗯，这很简单。 %2 是传递给 bat 文件的第二个参数。添加 ~ 将删除变量中的引号。

考虑以下简短的 bat 文件 (test.bat)：

@ECHO OFF
ECHO %2
ECHO %~2

你用test.bat p1 p2调用你的bat文件，它会输出：

p2

p2

现在试试test.bat p1 "p2"！这次的输出将是：

“p2”

p2

因此，如果您没有任何引号，则输出将是相同的，如果您有的话，%2 将保留它们，%~2 将删除它们。

Answer 3

%2 是传递给批处理文件的第二个参数。

myfile.bat firstArg secondArg

因为参数通常是文件路径，所以需要一些额外的语法来提取部分路径。

%~2 删除第二个参数上的任何 ""。

%~1         - expands %1 removing any surrounding quotes (")
%~f1        - expands %1 to a fully qualified path name
%~d1        - expands %1 to a drive letter only
%~p1        - expands %1 to a path only
%~n1        - expands %1 to a file name only
%~x1        - expands %1 to a file extension only
%~s1        - expanded path contains short names only
%~a1        - expands %1 to file attributes
%~t1        - expands %1 to date/time of file
%~z1        - expands %1 to size of file
%~$PATH:1   - searches the directories listed in the PATH
               environment variable and expands %1 to the fully
               qualified name of the first one found.  If the
               environment variable name is not defined or the
               file is not found by the search, then this
               modifier expands to the empty string    

%~dp1       - expands %1 to a drive letter and path only
%~nx1       - expands %1 to a file name and extension only
%~dp$PATH:1 - searches the directories listed in the PATH
               environment variable for %1 and expands to the
               drive letter and path of the first one found.
%~ftza1     - expands %1 to a DIR like output line

可能重复： What does %~d0 mean in a Windows batch file?