如何在 Windows 的命令行中创建一个空文件? [英] How can I create an empty file at the command line in Windows?

问题描述

如何在 DOS/Windows 命令行中创建一个空文件?

我试过了:

copy nul >文件.txt

但是总是显示文件被复制了.

标准 cmd 中还有其他方法吗?

它应该是一种不需要来自 Cygwin 的 touch 命令的方法或任何其他非标准命令.该命令需要从脚本运行，因此不能使用按键.

解决方案

没有重定向，LucVu 或 Erik Konstantopoulos 指向 出:

复制NUL EmptyFile.txt复制/b NUL EmptyFile.txt

---

"如何从批处理文件创建空文本文件?"(2008) 还指出:

type NUL >空文件.txt# 还回声.2>空文件.txt复制空文件.txt >nul #也在下面qid的回答中快速眼动.>空的文件fsutil file createnew file.cmd 0 # 在映射驱动器上创建文件

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Nomad 提到了 an原版:

C:\Users\VonC\prog\tests>aaaa >空的文件'aaaa' 不是内部或外部命令，也不是可运行的程序或批处理文件.C:\Users\VonC\prog\tests>dir文件夹 C:\Users\VonC\prog\tests27/11/2013 10:40 <REP>.27/11/2013 10:40 <REP>..27/11/2013 10:40 0 空文件

本着同样的精神，Samuel 建议 在评论中:

<块引用>

我使用的最短的基本上是 Nomad 的:

.>out.txt

它确实给出了错误:

'.'不被识别为内部或外部命令

但是这个错误是在 stderr 上.并且 > 仅重定向标准输出，其中 没有 产生.
因此创建了一个空文件.
此处可以忽略错误消息.或者，如 Rain 的 answer，重定向到 NUL:

.>out.txt 2>NUL

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(原答案，2009 年 11 月)

echo.> 文件名

(echo "" 实际上会将 "" 放入文件中！并且 echo 没有 '.' 会放入 "Command ECHO激活"在文件中...)

注意:生成的文件不是空，而是包含一个返回行序列:2 个字节.

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这个讨论指向真正的空文件的真正批处理解决方案:

  文件名目录文件名11/09/2009 19:45 0 文件名1 个文件 0 字节

<块引用>

"将 nul 响应传送到 set/p 命令，这将导致变量用于保持不变.像通常的 set/p 一样，字符串到等号的右边显示为没有 CRLF 的提示.

从这里开始，等号右边的字符串"为空...结果是一个空文件.

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与cd的区别.>文件名(在 Patrick Cuff 的回答 并且确实产生了一个 0 字节长度的文件) 是这种重定向位"( 技巧)可用于回显没有任何 CR 的行:

out.txt<nul (set/p z= world!) >>out.txt目录输出.txt

<块引用>

dir 命令应将文件大小指示为 11 个字节:helloworld!".

How can I create an empty file at the DOS/Windows command-line?

I tried:

copy nul > file.txt

But it always displays that a file was copied.

Is there another method in the standard cmd?

It should be a method that does not require the touch command from Cygwin or any other nonstandard commands. The command needs to run from a script, so keystrokes cannot be used.

解决方案

Without redirection, Luc Vu or Erik Konstantopoulos point out to:

copy NUL EMptyFile.txt
copy /b NUL EmptyFile.txt

---

"How to create empty text file from a batch file?" (2008) also points to:

type NUL > EmptyFile.txt
# also
echo. 2>EmptyFile.txt
copy nul file.txt > nul # also in qid's answer below
REM. > empty.file
fsutil file createnew file.cmd 0 # to create a file on a mapped drive

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Nomad mentions an original one:

C:\Users\VonC\prog\tests>aaaa > empty_file
'aaaa' is not recognized as an internal or external command, operable program or batch file.

C:\Users\VonC\prog\tests>dir

 Folder C:\Users\VonC\prog\tests

27/11/2013  10:40    <REP>          .
27/11/2013  10:40    <REP>          ..
27/11/2013  10:40                 0 empty_file

In the same spirit, Samuel suggests in the comments:

the shortest one I use is basically the one by Nomad:

.>out.txt

It does give an error:

'.' is not recognized as an internal or external command

But this error is on stderr. And > only redirects stdout, where nothing have been produced.
Hence the creation of an empty file.
The error message can be disregarded here. Or, as in Rain's answer, redirected to NUL:

.>out.txt 2>NUL

---

(Original answer, November 2009)

echo.>filename

(echo "" would actually put "" in the file! And echo without the '.' would put "Command ECHO activated" in the file...)

Note: the resulting file is not empty but includes a return line sequence: 2 bytes.

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This discussion points to a true batch solution for a real empty file:

 <nul (set/p z=) >filename

 dir filename
 11/09/2009  19:45                 0 filename
 1 file(s)                         0 bytes

The "<nul" pipes a nul response to the set/p command, which will cause the variable used to remain unchanged. As usual with set/p, the string to the right of the equal sign is displayed as a prompt with no CRLF.

Since here the "string to the right of the equal sign" is empty... the result is an empty file.

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The difference with cd. > filename (which is mentioned in Patrick Cuff's answer and does also produce a 0-byte-length file) is that this "bit of redirection" (the <nul... trick) can be used to echo lines without any CR:

<nul (set/p z=hello) >out.txt
<nul (set/p z= world!) >>out.txt
dir out.txt

The dir command should indicate the file size as 11 bytes: "helloworld!".

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