Quoting a long filenamed command in a for loop in a batch file

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Dealing with quotes in Windows batch scripts

This appears to be one of those maddening quoting issues. In this example program:

@echo off
set wmicpath=%windir%\System32\wbem\wmic.exe

for /f "usebackq" %%a in (`%wmicpath% COMPUTERSYSTEM GET SystemType ^| findstr /I "x64"`) do (
    echo %%a
)

The program runs just fine. Unless you try to quote the wmicpath. Imagine if you will that it contains a long path name. Then you should quote it. But I cannot quite get it to work. This fails:

for /f "usebackq" %%a in (`"%wmicpath%" COMPUTERSYSTEM GET SystemType ^| findstr /I "x64"`) do (

but this works!:

for /f "usebackq" %%a in (`"%wmicpath%" COMPUTERSYSTEM GET SystemType ^| findstr /I x64`) do (

as does this:

for /f "usebackq" %%a in (`"%wmicpath%" COMPUTERSYSTEM GET SystemType`) do (

There's something really odd about matching quotes in a for command. You can quote a command as long as you don't start quoting elsewhere...

Is it possible? I tried escaping at various points but I'm not sure about the escaping rules when quotes are involved...

Edit: I think this link might be the issue (ie: it's a bug): Pipe in for loop breaks double quoted variables

Answer 1

@echo off
    setlocal enableextensions disabledelayedexpansion
    set "wmicpath=%windir%\System32\wbem\wmic.exe"

    for /f "usebackq delims=" %%a in (`
        ^""%wmicpath%" COMPUTERSYSTEM GET SystemType ^| findstr /I "x64"^"
    `) do (
        echo %%a
    )

If you look at the start and end of the inner command, you will see two additional ^" (a escaped double quote). Your problem is that the for command is spawning a separate instance of cmd to handle the inner command, and this separate instance is removing the initial and final double quotes.

Why escaped quotes? To avoid this additional quotes being paired with the double quotes in the command that could lead to some other parsing problems.

You can run cmd /? to obtain the help page (sorry, i have a spanish locale so i will not include the output here). You will see a section about the /C and /K usage explaining quote removal behaviour.