How to redirect a FOR command in Windows batch

Question

I know how to redirect a Windows shell command with the >|>>|<|<< operators, but I cannot accomplish it for commands used inside a FOR command?

For instance:

for /f "usebackq tokens=*" %%I in (`__COMMAND__ 2>nul`) do (
    set MYVAR=%%I
)

You see, here I would like to silent the stderr of this __COMMAND__. The shell complaints that it does not expect a 2 in that place (same behaviour for other redirections).

Anybody can help here?

Answer 1

for /f "usebackq tokens=*" %%I in (`__COMMAND__ 2^>nul`) do (
    set MYVAR=%%I
)

in this case redirection and conditional execution operators need to be escaped with caret.

Or put everything in double quotes :

for /f "usebackq tokens=*" %%I in (`"__COMMAND__ 2>nul"`) do (
    set MYVAR=%%I
)

Using delayed expansion is also possible:

@echo off

setlocal enableDelayedExpansion

set "command=__COMMAND__ 2>nul"

for /f "usebackq tokens=*" %%I in (`!command!`) do (
    set MYVAR=%%I
)