4. WMIC, `where` & Calling PowerShell¶

What & why¶

Batch can't natively query system information — running processes with full paths, disk free space, OS version, service details, installed hotfixes. Historically you used wmic. Microsoft is removing wmic (deprecated since 2016, disabled by default on Windows 11 24H2). The modern answer is: call PowerShell for the hard parts. This lesson covers where, the remains of wmic, and — most importantly — how to embed PowerShell one-liners cleanly.

`where` — find executables and files¶

where git                       &rem prints full path(s) of git on PATH, errorlevel 1 if none
where /q node && echo have node  &rem /q = quiet, just set errorlevel
where /r C:\proj *.dll           &rem recursive file search
where python:*.exe                &rem in the "python" PATH entry

Standard "is this tool installed" guard:

where /q docker || ( echo docker is required 1>&2 & exit /b 1 )

`wmic` — still there on many machines, but don't rely on it¶

wmic os get Caption,Version,BuildNumber /value
wmic logicaldisk where "DeviceID='C:'" get FreeSpace,Size /value
wmic process where "name='chrome.exe'" get ProcessId,ExecutablePath
wmic path win32_localtime get * /value

/value (or /format:list) gives Name=Value lines that for /F "delims== tokens=1,2" parses cleanly:

for /F "tokens=2 delims==" %%v in ('wmic os get Version /value ^| findstr "="') do set "osver=%%v"

wmic is going away

On Windows 11 24H2 and Server 2025, wmic is not installed by default. Any script that depends on it will fail on new machines. Treat wmic as legacy: fine for a quick interactive check, not for scripts you ship. Port to PowerShell.

Calling PowerShell from batch¶

The pattern:

for /F "usebackq delims=" %%R in (`powershell -NoProfile -ExecutionPolicy Bypass -Command "EXPRESSION"`) do set "RESULT=%%R"

Flag	Why
`-NoProfile`	skip the user's `$PROFILE` — faster, predictable
`-ExecutionPolicy Bypass`	run despite a restrictive machine policy (for `-Command` it often isn't needed, but harmless)
`-Command "..."`	the code; use `-File script.ps1` for anything long
`-NonInteractive`	never prompt (good for scheduled tasks)

Examples¶

rem OS version:
for /F "usebackq delims=" %%v in (`powershell -NoProfile -Command "[Environment]::OSVersion.Version.ToString()"`) do set "OSVER=%%v"

rem Free space on C: in GB:
for /F "usebackq delims=" %%g in (`powershell -NoProfile -Command "[math]::Round((Get-PSDrive C).Free/1GB,1)"`) do set "FREEGB=%%g"

rem Is a process running:
powershell -NoProfile -Command "if (Get-Process chrome -ErrorAction SilentlyContinue) { exit 0 } else { exit 1 }"
if errorlevel 1 (echo chrome not running) else (echo chrome running)

rem Timestamp (see Intermediate Lesson 7):
for /F "usebackq delims=" %%t in (`powershell -NoProfile -Command "Get-Date -Format o"`) do set "NOW=%%t"

rem Download a file:
powershell -NoProfile -Command "Invoke-WebRequest -Uri 'https://example.com/x.zip' -OutFile 'x.zip'"

rem Unzip:
powershell -NoProfile -Command "Expand-Archive -Path 'x.zip' -DestinationPath '.\out' -Force"

rem Hash a file:
for /F "usebackq tokens=1" %%h in (`powershell -NoProfile -Command "(Get-FileHash 'setup.exe' -Algorithm SHA256).Hash"`) do set "SHA=%%h"

The quoting nightmare (and how to survive it)¶

Batch and PowerShell both use " and both have their own escapes. Rules that keep you sane:

Wrap the whole -Command in double quotes (batch's), and use single quotes inside for PowerShell strings:
```
powershell -NoProfile -Command "Get-ChildItem 'C:\Program Files' | Measure-Object"
```
If you need a double quote inside PowerShell, escape it for cmd as \" ... actually cmd doesn't use \; you pass "" or use PowerShell's backtick. This is where it gets ugly — move to -File:
```
powershell -NoProfile -File "%~dp0helper.ps1" -Name "%NAME%" -Count %COUNT%
```

Pass batch variables in by string-building the command before calling, or via -File ... -Args, not by hoping expansion works inside nested quotes:

set "PSCMD=(Get-Item '%TARGET%').LastWriteTime.ToString('yyyy-MM-dd')"
for /F "usebackq delims=" %%d in (`powershell -NoProfile -Command "%PSCMD%"`) do set "MTIME=%%d"

% inside the PowerShell code: in a .bat file, % is fine inside the backtick block unless it looks like %name% (batch will try to expand it). PowerShell's % alias for ForEach-Object often trips this — write ForEach-Object in full, or | %% ... no: use ForEach-Object.
Newlines: use ; to separate statements in a one-liner. For real multi-line logic, -File.

When to just write a `.ps1`¶

If your PowerShell is more than ~100 characters or has any " inside, stop fighting: put it in helper.ps1 next to the script and call powershell -NoProfile -File "%~dp0helper.ps1" args. You get proper syntax, quoting, -ErrorAction, and you can test it standalone.

`powershell` vs `pwsh`¶

powershell = Windows PowerShell 5.1, ships with Windows, always present. Slower start (~150–250 ms).
pwsh = PowerShell 7+, cross-platform, not installed by default. Faster, better language.

For portability in a batch script that must run anywhere, use powershell. If you control the machines and installed pwsh, prefer it. Probe:

where /q pwsh && set "PS=pwsh" || set "PS=powershell"
%PS% -NoProfile -Command "..."

Performance note¶

Each powershell -Command call is a fresh process — 150 ms+ on Windows PowerShell. Calling it 500 times in a loop is a 2-minute script. If you're doing that, write the loop in PowerShell and call it once. Batch's job then is just to be the entry point. See Lesson 6.

Common mistakes¶

Shipping a script that uses wmic — dead on new Windows. Port to PowerShell.
Double quotes inside -Command "..." — cmd ends the string early. Use single quotes inside, or -File.
%var% inside the PowerShell block getting eaten by batch — build the command into a variable first, or use -File -Args.
PowerShell's % alias in a .bat — collides with batch %. Spell out ForEach-Object.
Forgetting -NoProfile — slow, and a user's profile can change behaviour or emit text that corrupts your for /F capture.
Not handling PowerShell errors — a failed Invoke-WebRequest may still exit 0 unless you add -ErrorAction Stop / check $? / exit $LASTEXITCODE.
pwsh assumed present — probe with where /q pwsh.
Calling PowerShell in a tight loop — 150 ms × N. Invert: one PowerShell call does the loop.

Exercises¶

Replace a wmic logicaldisk free-space check with a PowerShell one-liner; print free GB on every fixed drive.
Write :have TOOL using where /q; use it to require git, curl, and 7z, listing all that are missing before exiting.
Get the machine's OS caption and build number via PowerShell into two variables.
Download a small file with Invoke-WebRequest, verify its SHA-256 against an expected value (compute with Get-FileHash), and exit /b 1 on mismatch.
Move a 3-line PowerShell snippet from an ugly -Command string into helper.ps1 called with -File and parameters. Note how much clearer it is.
Benchmark: call powershell -NoProfile -Command "1" 50 times in a for /L loop and time it. Then do the equivalent work in a single PowerShell invocation. Compare.

Recap¶

where / where /q = locate executables, the standard "is X installed" guard.
wmic is deprecated and absent on new Windows — don't put it in shipped scripts.
Call PowerShell for system info: for /F "usebackq delims=" %%R in ('powershell -NoProfile -Command "EXPR"') do set "R=%%R".
Quoting: batch " outside, PowerShell ' inside; escalate to -File script.ps1 the moment you need " inside or the logic grows.
Use powershell (5.1, always present) for portability; probe for pwsh.
One PowerShell process ≈ 150 ms — never call it in a hot loop; invert the control flow.

Next: Text processing with findstr →

4. WMIC, where & Calling PowerShell¶