如何使Windows CMD ECHO恰好回显单个字符? [英] How to get Windows CMD ECHO to echo exactly one single character?

问题描述

Windows Internal CMD ECHO 的(非正式)文档显示了一些有趣的技巧它.但是，我还没有找到回声单个字符的方法.

快速注释，下面使用的 od 来自Git(或Gow)安装

Quick note, od used below, is from a Git (or Gow) installation

例如，此回显是带有"windows"换行符(\r\n)的'a':

For instance, this echo's the 'a' with a 'windows' newline (\r\n):

>echo a| od -A x -t x1z -v -
000000 61 0d 0a                                         >a..<
000003

技巧(也在现在的文档中)echo什么也没有:

And this trick (also in the docs now) echo's nothing:

><nul (set/p _any_variable=)| od -A x -t x1z -v -
000000

因此，我希望它仅回显'a':

So I would expect this to echo just the 'a':

><nul (set/p _any_variable=a)| od -A x -t x1z -v -
000000 61 20                                            >a <
000002  

但是它最后增加了额外的空间.

是否可以只做一个字符?

Is it possible to just do a single character?

@Aacini在下面的评论中正确回答了(第一个问题)，但是如果他没有创建答案，则为:

@Aacini answered (the first question) correctly in a comment below, but in case he does not create an answer, here it is:

>set /P "=a" < NUL | od -A x -t x1z -v -
000000 61                                               >a<
000001

还有什么技巧可以使它更精确，例如UNIX echo 和-n(无新行)和-e(使用反斜杠解释)，因此我可以将输出与此类似:

And are there any tricks to get more precise like the UNIX echo with a -n (no new line) and -e (use backslash interpretation) so I could similar outputs to this:

>unix_echo -n -e "a\n" |  od -A x -t x1z -v -
000000 61 0a                                            >a.<
000002

推荐答案

set /P命令用于提示用户并接受输入.例如:

The set /P command is used to prompt the user and accept an input. For example:

set /P "name=Enter your name: "

此命令显示提示信息，并将光标置于其后.我们可能会很好地利用此行为来显示提示"，该提示在CR + LF中没有 not 结尾，然后完成将Stdin重定向到NUL的虚拟输入.在这种情况下，不需要变量名称:

This command show the prompt message and place the cursor after it. We may make good use of this behavior to show a "prompt" that does not end in CR+LF, and then complete the dummy input redirecting Stdin to NUL. In this case, the variabe name is not needed:

set /P "=Text with no CR+LF at end" < NUL

这样，仅输出一个字符，请使用以下命令:

This way, to output just one character, use this:

set /P "=a" < NUL

请注意，set /P命令会在提示消息中省略任何前导空格.这意味着不可能使用此方法仅显示空格.

Note that set /P command omit any leading space from the prompt message. This means that it is not possible to use this method to show only spaces.

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