Difference between $? and $LastExitCode in PowerShell

Question

In PowerShell, what is the difference between $? and $LastExitCode?

I read about automatic variables, and it said:

$? Contains the execution status of the last operation. It contains TRUE if the last operation succeeded and FALSE if it failed.

$LastExitCode Contains the exit code of the last Windows-based program that was run.

In the definition of $? it doesn't explain what succeed and fail mean.

I ask because I presumed that $? is True if and only if $LastExitCode is 0, but I found a surprising counter-example: $LastExitCode=0 but $?=False in PowerShell. Redirecting stderr to stdout gives NativeCommandError.

Joey · Accepted Answer · 2012-05-20 07:49:50Z

141

$LastExitCode is the return code of native applications. $? just returns True or False depending on whether the last command (cmdlet or native) exited without error or not.

For cmdlets failure usually means an exception, for native applications it's a non-zero exit code:

PS> cmd /c "exit 5"
PS> $?
False
PS> cmd /c "exit 0"
PS> $?
True

Cancelling a cmdlet with Ctrl+C will also count as failure; for native applications it depends on what exit code they set.

edited May 20, 2012 at 7:49

answered May 19, 2012 at 14:30

Joey

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5 Comments

Colonel Panic Over a year ago

Thanks Joey. I myself thought $? meant non-zero exit code, but I've just found a surprising counterexample. See stackoverflow.com/questions/10666101/…

Joey Over a year ago

That's an interesting one. I would believe this to be a bug (because it behaves inconsistently between different PowerShell hosts).

majkinetor Over a year ago

And different cmdlets: @iex abcde@ for instance returns neither $?=False or $LastExitCode > 0

berkus Over a year ago

Invoke-Expression "rustc --version"; Write-Host $? $LastExitCode prints True 0 -- all good Invoke-Expression "rustc --sdasdasd"; Write-Host $? $LastExitCode prints True 1 -- oops

berkus Over a year ago

In addition rustc --sdasdasd; Write-Host $? $LastExitCode prints False 1 -- so there is a play of combination of factors depending on whether you use built-in commands and/or external commands.

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