Question

I would like to write a simple windows batch file that reads from standard input a text file,
and writes to standard output the same content, but as one long line, sort of like what you would
get if you replaced each carriage-return-line-feed in the input by a blank.

Anyone know how to do this?

Answer 1

You could paste all lines together, if the total size is less than 8192 characters.
And echo the result to the new file with only one CR/LF at the end.

setlocal EnableDelayedExpansion
set "text="
for/f "delims=" %%a in (multiLine.txt) do (
  set "text=!text!%%a"
)
>newFile.txt echo !text!

You could also use set /p to output text without CR/LF, but it can’t handle equal signs nor white spaces at the front.

EDIT: The first solution works, but has problems with empty lines and lines with exclamation marks.

This is a solution that eliminates both problems.

@echo off
setlocal EnableDelayedExpansion
set file=multiLine.txt

set "AllText="
for /F "tokens=2 delims=:" %%L in ('find /c /v "" %file%') do set /a "len=%%L"

<%file% ( 
    for /L %%n in (1,1,!len!) DO (
        set "line="
        set /p "line="
        set "AllText=!AllText!!line!"
    )
)
>newFile.txt echo(!AllText!