How do I write to standard error in PowerShell?

Question

I'm having trouble figuring out how to both echo to the standard error stream and redirect the error stream of an executable.

I have come from a Bourne shell and Korn shell background, of which I would use;

# Write to stderr echo "Error Message!" >&2  # Redirect stderr to file /do/error 2>/tmp/err.msg 

Answer 1

Use Write-Error to write to stderr. To redirect stderr to file use:

 Write-Error "oops" 2> /temp/err.msg 

or

 exe_that_writes_to_stderr.exe bogus_arg 2> /temp/err.msg 

Note that PowerShell writes errors as error records. If you want to avoid the verbose output of the error records, you could write out the error info yourself like so:

PS> Write-Error "oops" -ev ev 2>$null PS> $ev[0].exception oops 

-EV is short (an alias) for -ErrorVariable. Any errors will be stored in the variable named by the argument to this parameter. PowerShell will still report the error to the console unless we redirect the error to $null.

Answer 2

You probably want this:

$host.ui.WriteErrorLine('I work in any PowerShell host') 

You might also see the following, but it assumes your PowerShell host is a console window/device, so I consider it less useful:

[Console]::Error.WriteLine('I will not work in the PowerShell ISE GUI')