如何在Batch的type命令中正确使用变量？消除末尾空格问题

Ah, I've run into this exact Batch quirk before! That trailing space sneaking into your variable name comes from how the echo|set /p syntax handles output—it unintentionally adds an extra space at the end of your filename when writing to beforetemp.txt. Let's fix this so your generated header has the correct indexhtml[] variable name instead of index html[].

Solution 1: Fix the Temporary File Generation #

The core problem is your filename output line. Replace the echo|set /p command with a more reliable method that doesn't add extra whitespace:

@echo off
setlocal enabledelayedexpansion
set /P filename=Enter File name (w/o .html extension):
if exist "..\website\!filename!.html" (
    <nul set /p "dummyvar=!filename!">beforetemp.txt
    type before.txt beforetemp.txt before2.txt "..\website\!filename!.html" after.txt > "..\server\!filename!html.h"
    del beforetemp.txt  // Clean up the temporary file after use
) else (
    echo FILE at website\!filename!.html DOES NOT EXISTS!
    pause
)
endlocal
exit 0

Why this works: #

• <nul set /p "dummyvar=!filename!" writes the filename to the temp file without adding a trailing newline or space. Unlike echo|set /p, this syntax uses nul as the input source for set /p, which avoids introducing extra whitespace.
• enabledelayedexpansion is enabled to handle any special characters in filenames (a safe practice even if your use case doesn't require it right now).

Solution 2: Remove the Temporary File Entirely (Cleaner Approach) #

You can eliminate the temp file step altogether by chaining your output commands directly into the final header file:

@echo off
setlocal enabledelayedexpansion
set /P filename=Enter File name (w/o .html extension):
if exist "..\website\!filename!.html" (
    (
        type before.txt
        <nul set /p "=!filename!"  // Insert filename without extra whitespace
        type before2.txt
        type "..\website\!filename!.html"
        type after.txt
    ) > "..\server\!filename!html.h"
) else (
    echo FILE at website\!filename!.html DOES NOT EXISTS!
    pause
)
endlocal
exit 0

This combines all your input files and the filename into a single output stream, which gets redirected straight to your final header. The <nul set /p "=!filename!" line inserts the filename directly between before.txt and before2.txt with no unwanted spaces.

Verify the Result #

After applying either fix, your generated header will correctly look like this:

#include <arduino.h>
const char indexhtml[] PROGMEM = R"====(
<html> ... </html>
)====";

内容的提问来源于stack exchange，提问作者Torge Rosendahl