Calling a command line application outtputing to stderr with piping - shell

I'm looking to get both std-err and std-out streams from a binary I have called by powershell piped to a powershell cmdlet. I cant seem to get the syntax or find the right command.
I have a little Write-Smartly cmdlet that I want to process line-by-line of combined standard-error and standard output. It is itself a wrapper on Write-Host that adds some indenting.
My first attempt, I want to:
use -ErrorAction to indicate to powershell not to treat standard-error messages as exceptions
use 2>&1 to combine standard-error and standard-output streams into a pipelineable output
use ... | MyCmdlet to format the combined output & error streams to their ultimate output
giving me:
& $myApp $args --% -ErrorAction 'SilentlyContinue' 2>&1 | Write-Smartly
Unfortunatly this ended up passing -ErrorAction SilentlyContinue and 2>&1 into my application as arguments. Standard-error did show up as regular output, but it was written directly to host, rather than piped to WriteSmartly.
So I made a few modifications to try to correct this:
$ErrorActionPreference = 'SilentlyContinue'
&{ & $myApp $args } 2>&1 | Write-Smartly
This simply causes my error output to disappear.
I also played around with Start-Process, but it seems too heavyweight to allow me to get things out of it with a pipe. I think that Invoke-Command or Invoke-Expression might be helpful here but I'm not sure what their use cases are.
How can I capture both standard-error and standard-output as a pipelined value in powershell?

Related

Poweshell Start-Job from serviceAccount using SailPoint IQService

So there are several factors in play with this question, so here they are:
SailPoint 8.2 and IQService 8.2
Windows Server 2016
A service Account(Domain Admin)
An interactive User account (Domain admin)
Powershell 5.1 build 14393 revision 4583
So what we have is SailPoint is executing a rule on its end, sending over some information to IQService, and IQService is executing the PowerShell scripts as the service account. In one of the PowerShell scripts, we have the following command:
LogToFile("calling start job")
$j = Start-Job -ScriptBlock { C:/SailPoint/Scripts/PowershellContainerAfterCreateRetry.ps1 -sAMAccountName $args[0] -company $args[1] } -ArgumentList $sAMAccountName, $company -Name 'PowershellContainerAfterCreateRetry'
LogToFile($j | Select-Object -Property *)
LogToFile("finished start-job")
and this is where things get interesting because this command, as you can note, we can log to file to see what its output is, which is as follows:
calling start job
#{
State=Running; HasMoreData=True;
StatusMessage=;
Location=localhost;
Command= C:/SailPoint/Scripts/PowershellContainerAfterCreateRetry.ps1 -sAMAccountName $args[0] -company $args[1] ;
JobStateInfo=Running;
Finished=System.Threading.ManualResetEvent;
InstanceId=aa889c06-7a8a-402e-807a-880d02465bdd; Id=1;
Name=PowershellContainerAfterCreateRetry;
ChildJobs=System.Collections.Generic.List`1[System.Management.Automation.Job];
PSBeginTime=10/15/2021 21:14:22; PSEndTime=;
PSJobTypeName=BackgroundJob;
Output=System.Management.Automation.PSDataCollection`1[System.Management.Automation.PSObject];
Error=System.Management.Automation.PSDataCollection`1[System.Management.Automation.ErrorRecord];
Progress=System.Management.Automation.PSDataCollection`1[System.Management.Automation.ProgressRecord];
Verbose=System.Management.Automation.PSDataCollection`1[System.Management.Automation.VerboseRecord];
Debug=System.Management.Automation.PSDataCollection`1[System.Management.Automation.DebugRecord];
Warning=System.Management.Automation.PSDataCollection`1[System.Management.Automation.WarningRecord];
Information=System.Management.Automation.PSDataCollection`1[System.Management.Automation.InformationRecord]}
finished start-job
When I execute this command either by itself OR within this script using Windows PowerShell ISE, it completes with no issue and calls the script in question, and everything works perfectly! (whether I am using my interactive account OR the service account)
When this script executes using the IQService, something "else" is happening - I say something "else" because I don't have any log files or errors; it just seems to disappear into the ether. (I have a log write out five lines into the PowerShell script, so one would think I would at least get SOMETHING!?!? I am out of ideas...thoughts?
As a minor note, I ran an experiment that showed me that there is something strange about the setup which should have succeeded without issue - like the above it appears to execute (because I can see the same information above, that shows that the job has started). Still, just like the above, it never actually "appears" to complete or error out. The only thing I can think of is that somehow the primary script closing out is causing this to close out as well - but I would think it would be able to get a couple of log files written to if that was the case? Anyway...thanks for reading!
$doit = {
"test" | Out-File -filepath ("c:\test.txt") -append
}
Start-job -ScriptBlock $doit
i think Start-Job is the problem here, as iqservice will launch a powershell script process and that may not support the background job aspect you are trying to use.
if you need to have something retry or wait and loop, you'll need to use another identityiq/iqservice mechanism (a workflow in iiq perhaps that calls down to AD when conditions are, timer is hit, etc.) beyond start-job inside of an iqservice powershell script.

Powershell equivalent of Perl's $CHILD_ERROR

I essentially require a functionality in Powershell that executes the given string (it can be a CMD/Powershell command, a perl/python/powershell with arguments or an exe with arguments, etc) captures its exit value.
In perl I would pass the string to 'system()' and use the '$CHILD_ERROR' perlval and shift it to access the exit code.
In powershell I am clueless.
I tried using Invoke-Expression, but even if the expression passed to Invoke-Expression fails, the Invoke-Expression call itself will have succeeded.
You can use $LASTEXITCODE to get the exit code from an external program or the Boolean $? to check if the last operation succeeded or failed. Run Get-Help about_Automatic_Variables -ShowWindow from a PowerShell console to see more details.
You may want to check out the & (call) command as an alternative to Invoke-Expression when running external programs. Run Get-Help about_Automatic_Variables -ShowWindow from a PowerShell console for details.
Also remember you may be able to just call the external program without using one of the commands above. See the example below:
param($Hostname="127.0.0.1", $Tries=1, $Wait=1000)
$output = ping.exe $Hostname -n $Tries -w $Wait # captures anything written to stdout
$output|? {$_ -match 'Request timed out'}|Write-Warning
$LASTEXITCODE # returns the exit code from ping.exe
You can copy it to a test.ps1 file and run it from a PowerShell console window (.\test.ps1 8.8.8.8 for instance) to see how it works.

Autologon.exe via command line and get result

Is there a way I can execute sysinternals Autologon.exe from command line (Powershell) and get the result, i.e. know if the credentials entered were correct?
If I use the GUI and not the command line then I do get message with this info..
Thanks.
You can run any Windows .exe/cmd/bat/vbs from PoSH, as long as you call it correctly.
PowerShell: Running Executables
https://social.technet.microsoft.com/wiki/contents/articles/7703.powershell-running-executables.aspx
There are several different methods for running executables as well as invoking code. How do you know which one to use for the job? Here is an outline of the methods with examples and general use.
Regarding ---
"If I use the GUI and not the command line then I do get message with this info.."
This is because Autologon.exe is doing this work and returning the result. SO, it's Autologon. PoSH will not get in Autologon's way / process, but you can get the exit code from external tools as long as you know what they are. I've not tried to this with Autologon. Yet, in most cases, it's a Boolean response: success or failure, 0 or 1, or 1 or 2. The Start-Process cmdlet allows you to trap error / exit code from a process, using the -PassThru parameter. Often that is use in concert with the -wait parameter as well.
Something like:
$AutologExitCode = Start-Process -FilePath = Autologon.exe -ArgumentList $SomeArguments -NoNewWindow -Wait -PassThru
"The error/exit code from AutoLogon is $($AutologonExitCode.ExitCode)"
Full disclosure: We do not allow Autologon in our environment. So, I've spent no time using Autologon, but the above premise would be the same as other exe's.

PowerShell 2.0 can't redirect stdout

Sometimes, the answer is "no". This turns out not to be a question, but more of a cri de coeur (OK, just complaining).
The Team Foundation Server 2010 PowerShell snap-in exports a cmdlet called Get-TfsPendingChange, which does what it sounds like.
If there are no pending changes, Get-TfsPendingChange echoes "There are no pending changes." on standard output. I never asked it to. The following attempts at suppressing that output all fail:
$pcs = $(Get-TfsPendingChange -Server $server "$/foo/bar" -User $env:USERNAME -r ) | out-null;
$($pcs = Get-TfsPendingChange -Server $server "$/foo/bar" -User $env:USERNAME -r ) | out-null;
$pcs = Get-TfsPendingChange -Server $server "$/foo/bar" -User $env:USERNAME -r | out-null;
I'm not getting errors, but the text output is not redirected. What IS redirected, is the normal successful output of the cmdlet, in the case where there are pending changes for it to return. The ONLY output you can suppress is the useful output. If there are zero pending changes, you get text garbage via stdout. If there are any actual pending changes, that stream (of objects, not text) can be redirected to the null device, but that's worse than useless.
So it appears that text on stdout is a side effect from this cmdlet, not the cmdlet's output, and it cannot be redirected in PowerShell. The PowerShell redirect operators > and |, without the fileno specifiers (2 in PS2, 2, 3, 4, 5, and * in PS3/PS4), work on the object stream, which is not stdout. This would be fine if stdout had been replaced by this new object stream concept (or if some genius on the TFS team hadn't decided that cmdlets should spew random text noise in all directions as a side effect).
The garbage output definitely is on stdout, not stderr. I can redirect the standard output of the whole script to nul when I run it from cmd.exe, and that works as expected, because duh:
c:\>powershell .\tfstest.ps1 > nul
However, I do not want to suppress all the output from the entire script. Just the output from one snapin cmdlet. It's not the end of the world, but it's irritating to have random stuff that I call echoing garbage I have no control over. The script otherwise works correctly (see UPDATE).
One workaround would be to prefix everything I want to echo on stdout with some arbitrary string (say "KLUDGEPREFIX"), and run the whole mess from a batch file which pipes the PowerShell script's output through find /v KLUDGEPREFIX and then through a PowerShell fragment that strips off the prefix from each line.
Instead, I'm going to write the rest of the script around the problem so it looks like what they get is what I intended, because, in fact, I was going to tell them they didn't have any pending changes anyhow. It's been a valuable exercise, however, in terms of getting my head inside PowerShell.
UPDATE: This script turned out to be fragile, unreliable, glacially slow, and impossible to run on any computer but the one where I originally wrote it.
I replaced it with a Perl script that took 1/10 the time to write, executed 10 times as fast, and does the same task better without any foolishness. PS and the TFS PS snap-in are great ideas but they both need a lot of work before they'll be ready for release.
I'm not familiar with Team Foundation Server, but most likely the cmdlet writes to the host rather than one of the output streams. Output to the host cannot be redirected in PowerShell, but if you run a PowerShell script in CMD the host output goes to STDOUT (as does the success output stream) and can be redirected there.
Demonstration:
PS C:\> cat .\test.ps1
Write-Host 'foo'
PS C:\> .\test.ps1 | Out-Null
foo
PS C:\> .\test.ps1 >$null
foo
PS C:\> & cmd.exe /c powershell.exe -File .\test.ps1
foo
PS C:\> & cmd.exe /c powershell.exe -File .\test.ps1 `>nul
PS C:\> & cmd.exe /c powershell.exe -File .\test.ps1 >$null
PS C:\> _
if you add 2 in front of the > it will only redirect error. likewise with 1 for non errors (stdout). So if you want all stdout, but not stderr to go away you can type
$pcs = Get-TfsPendingChange -Server $server "$/foo/bar" -User $env:USERNAME -r 1> $null
$null can be used as an equivalent to /dev/null. your code probably creates the file "nul" on disk.

Register-ScheduledJob and Write-Host

I'm using Register-ScheduledJob to register job in powershell in background job I execute script. This script contains some commands like Get-Process and Write-Host command. And...
Altough every command is executed in results I don't see outputs from write-hosts (get-Process is is ok)
Maybe someone know why?
Write-Host writes to the host, which is the app that the script is running in (PowerShell.exe for instance), so it is output explicitly to the screen, and DOES NOTHING when you're running in a non-interactive environment. You should never use that to output data that you want to collect, only for lightweight debugging or for printing to the screen in interactive scripts.
You should generally use write-output for the data that you want to collect as output.
Although you can also use the debug/warning/error output (those are collected by the job, but not shown in the regular output).
Thank You very much. Write-Output helped.
Additionaly what i discover during last days and could be helpful for others: if you start scheduled background job and in this job start powershell script like this:
Register-ScheduledJob -Name1 temp -ScheduledJobOption $option -ScriptBlock {
D:\scprit.ps1
}
Your job will never end because after finish script powershell window is still open. So additionaly you have to add exit in your scriptblock:
Register-ScheduledJob -Name1 temp -ScheduledJobOption $option -ScriptBlock {
D:\scprit.ps1
Exit-PSSession
}

Resources