How to split double quoted line into multiple lines in Windows batch file?

Question

Long commands in Windows batch files can be split to multiple lines by using the ^ as mentioned in Long commands split over multiple lines in Windows Vista batc

Answer 1

I came up with my own method for this today, and I've never seen it suggested anywhere so I thought I'd post it here. Certainly, it's not elegant in an objective sense. I would say it has it's own unique kind of ugly and some limitations, but I find it far more "ergonomic" when compared to the alternatives.

Specifically, this method has the unique characteristic of not needing to escape anything, while still performing typical variable substitution. This enables me to to take some string that looks exactly how I want it, spread it across multiple lines, and add a prefix to each line without changing anything else in the string. Thus, there's no trial-and-error needed to figure out how special characters and escape characters might interact. Overall, I think it reduces the cognitive load needed to deterministically produce a complicated string variable over multiple lines, which is good for me because I don't want to have to think hard and get frustrated with incidental complexity like the nuances of the windows command interpreter. Also, a similar technique can be used on linux bash, making it somewhat portable.

Note: I've not thoroughly tested it, it might not work for some use cases, I don't know. However, the example has a fair number of seemingly troublesome characters an it works, so it seems somewhat robust.

set IMAGE_NAME=android-arm64
set CMD=docker run --rm
set CMD=%CMD% --platform=linux
set CMD=%CMD% -v %CD%:/work
set CMD=%CMD% dockcross/%IMAGE_NAME%
set CMD=%CMD% /bin/sh -c
set CMD=%CMD% "mkdir build-%IMAGE_NAME% &&
set CMD=%CMD% cd build-%IMAGE_NAME% &&
set CMD=%CMD% cmake .. &&
set CMD=%CMD% cmake --build ."

echo %CMD%

In my case, it's a command, so I can run it with:

%CMD%

I'd be open to any feedback or suggestions about this method. Perhaps it can even be improved.