PowerShell:
Writing to standard error

How to:

PowerShell simplifies the process of writing to stderr through the use of the Write-Error cmdlet or by directing output to the $host.ui.WriteErrorLine() method. However, for direct stderr redirection, you might prefer using .NET methods or the file descriptor redirection offered by PowerShell itself.

Example 1: Using Write-Error to write an error message to stderr.

Write-Error "This is an error message."

Output to stderr:

Write-Error: This is an error message.

Example 2: Using $host.ui.WriteErrorLine() for direct stderr writing.

$host.ui.WriteErrorLine("Direct stderr write.")

Output to stderr:

Direct stderr write.

Example 3: Using .NET methods for writing to stderr.

[Console]::Error.WriteLine("Using .NET method for stderr")

This method’s output:

Using .NET method for stderr

Example 4: Redirecting error output using file descriptor 2>.

File descriptors in PowerShell can redirect different streams. For stderr, the file descriptor is 2. Here’s an example of redirecting stderr to a file named error.log while executing a command that generates an error.

Get-Item NonExistentFile.txt 2> error.log

This example does not produce console output, but generates a file error.log in the current directory containing the error message from attempting to access a file that does not exist.

In conclusion, PowerShell provides multiple methods for effectively writing and managing error output, allowing for sophisticated error handling and logging strategies in scripts and applications.