Powershell StandardOutput buffer too small for external command - powershell

Question

Some useful info beforehand. What I'm attempting to do is read in output from an external command, specifically steamcmd, using powershell start-process and System.diagnostics.ProcessStartInfo.
What I'm running into is RedirectStandardOutput buffer limit of 4096 bytes. The output I'm getting from the steamcmd is more than that buffer, so I'm only getting a portion of what I need. I have no other method for getting this data, other than calling steamcmd.
You can see the output as well if you have steamcmd (it's free) and running this.
steamcmd +login anonymous +app_info_update 1 +app_info_print 443030 +quit
This will download all the manifest info about that appid.
I've tried to redirect to a file and also to a variable, both work as expected, it's just that it's cut short by the buffer. There also doesn't appear to be a powershell method in System.Diagnostics.Process to wait for the OutputDataReceived event.
Code used (stolen from another STackOverflow question)
$psi = New-object System.Diagnostics.ProcessStartInfo
$psi.CreateNoWindow = $true
$psi.UseShellExecute = $false
$psi.RedirectStandardOutput = $true
$psi.RedirectStandardError = $true
$psi.FileName = "C:\Path\to\SteamCMD.exe"
$psi.Arguments = "+login anonymous +app_info_update 1 +app_info_print 443030 +quit"
$process = New-Object System.Diagnostics.Process
$process.StartInfo = $psi
[void]$process.Start()
$output = $process.StandardOutput.ReadToEnd()
$process.WaitForExit()
$output
I think the actual issue is that steamCMD just outputs in one big write instead of line by line. I guess a better question would be, how can I increase the standardoutput buffer size of Start-Process or System.Diagnostics.Process.
Note: running the steamcmd > somefile.txt results in same buffer limit.

Answer 1

steamcmd.exe appears to work properly only if run from an empty subdirectory, at least for this command line.
I can't explain it, but I was able to repro your issue when I rand the command twice.
Here is one way to work around the issue. Run steamcmd.exe from an empty directory. Depending on your needs, you could use a static temp dir and clean it before each run, or generate a temp dir and use that and decide how to clean it up later.
CODE
$steamcmd = "L:\test\steam\steamcmd.exe"
# steam works best if run in an empty directory
# why, i have no clue...
$tempName = [System.IO.Path]::GetRandomFileName()
$parentDir = Split-Path $steamcmd -Parent
$tempPath = Join-Path $parentDir $tempName
$null = New-Item $tempPath -ItemType Directory
$null = Copy-Item $steamcmd $tempPath
Write-Output "temp directory is '$tempPath'"
$steamcmdTemp = Join-Path $tempPath 'steamcmd.exe'
Write-Output "Running '$steamcmdTemp'..."
$output = & $steamcmdTemp +login anonymous +app_info_update 1 +app_info_print 443030 +quit
$now = [DateTime]::Now.ToString("yyyyMMdd HHmmss")
$outFile = "output {0}.txt" -f $now
$outputFile = Join-Path $parentDir $outFile
Write-Output "Saving output to '$outputFile'"
$output | Out-File $outputFile -Force
# todo: deal with removing the temp dir...
# or keep cleaning and reusing a static name...
Write-Output "Remember to cleanup '$tempPath'"