How do I nest a Windows FOR command in the 'set' of another FOR command?

I have a directory of configuration files. If a file contains a 'STATE = 3' entry, I want to extract the value of the TCPHOST entry and the name of the file. There are a lot of nested quotes in that so I used "usebackq" but without success:

c:\config>For /F "usebackq tokens=1,3 delims==: " %A in (`FOR /F "tokens=1 delims= " %P IN ('FINDSTR /M /I /R /C:"*STATE.*=.*3" * ') DO ('FINDSTR /I /S /C:"TCPHOST" %P')`) do (echo '%A|http://%B')

`) was unexpected at this time.

I have replaced the inner "FOR" command with a simple "DIR" and the results are technically correct (albeit meaningless) - I display the first and third tokens of the output.

Am I trying to do something impossible with these commands. (I am aware that I could probably write a bat file or PowerShell script but that's not my question.)

I was able to get the result that (I guess) you want, sticking to CMD, but breaking your monster command into multiple steps, with an intermediate file:

copy/y nul %temp%\out1.txt
FOR /F "tokens=1 delims= " %P IN ('FINDSTR /M /I /R /C:"STATE.*=.*3" * ') DO (FINDSTR /I /S /C:"TCPHOST" %P) >> %temp%\out1.txt
For /F "tokens=1,3 delims==: " %A in (%temp%\out1.txt) do (echo '%A^|http://%B')
del %temp%\out1.txt

I can’t figure out exactly why you got the error you got, but here are a few possible show-stoppers in your code:

• "*STATE.*=.*3" should be "STATE.*=.*3" (or maybe ".*STATE.*=.*3") because starting a regular expression with * is invalid.
• DO ('FINDSTR /I /S /C:"TCPHOST" %P') should be DO (FINDSTR /I /S /C:"TCPHOST" %P) — the command after DO shouldn’t be in quotes.
• echo '%A|http://%B' should be echo '%A^|http://%B' (to get a literal | rather than trying to pipe echo '%A into http://%B') or maybe echo %A^|http://%B (to avoid getting single quotes in the output — or do you want them?).