In this post some is surprised that the following example doesn't work properly when run in a script
get-process | select-object cpu, name
dir | Select-Object name, length
When I put this in a script the second command doesn't show the length
And the answer to this:
PowerShell is joining both outputs. You could pipe the first output to
Format-Table [-auto] if you don't mind the format. Alternatively, you
can separate the first output from the following formatted output by
piping it to Out-Default, Out-Host, Out-string or Write-host
Now my question is why is it joining the output of those two seemingly unrelated commands and why doesn't this happen in the interactive console? They are not connected with a pipe. How does this work?
It seems that I still haven't quite understood basic concepts about piping in scripts.
See if this helps: blogs.msdn.com/b/powershell/archive/2006/04/30/586973.aspx
This issue isn't really the pipeline, but the default console formatting
Related
Running the command help firewall | Select-Object Category. The result is one column blank Category.
The strange thing is that the empty rows number represent the amount of rows that help firewall would result without calling piping it to Select-Object
Or I'm trying to filter the output of help firewall to return only rows with Name that starts with "Get". Running help firewall | Where-Object Name -like "Get" just returns nothing.
Why aren't these pipes on help working? They are working perfectly on other commands.
Powershell Version 5.1 and using default windows console.
To complement Zilog80's helpful answer with background information:
Get-Command help reveals that help is not a mere alias of the Get-Help cmdlet, but a (built-in) function (submit $function:help to see its definition).
As you've noticed yourself:
while Get-Help outputs an object ([pscsustomobject]) with properties that reflect help-topic metadata such as Category, which is then rendered as display text by PowerShell's output-formatting system,
the help function returns strings - a stream of text lines representing the rendered help topic - of necessity.
You can observe the difference in output type by piping to the Get-Member cmdlet (help firewall | Get-Member vs. Get-Help firewall | Get-Member)
The purpose of the help function is to wrap Get-Help with interactive paging, to allow convenient navigation through lengthy help topics that don't fit onto a single console (terminal) screen.
This paging is provided via an external program (by default, more.com on Windows, and less on Unix-like platforms, configurable via $env:PAGER, but only in PowerShell (Core) 7+), and since PowerShell only "speaks text" when communicating with external programs, help must send a stream of strings (lines for display) to them, which it does via
Out-String -Stream.
Note:
When the external paging programs find that their stdout stream isn't connected to a console (terminal), they take no action other than simply passing the input through (in Unix terms, they then behave like cat).
Hypothetically, the help function itself could determine this condition and then (a) not pipe to the paging program and (b) relay the object output by Get-Help as-is.[1] However, determining a command's output target from inside that command, using PowerShell code, may not even be possible.
[1] The function actually already takes this action when a custom pager defined via $env:PAGER is found to be a PowerShell command rather than an external program.
Check the feedback from help help in PowerShell :
You can also type `help` or `man`, which displays one screen of text at a
time. Or, ` -?`, that is identical to `Get-Help`, but only
works for cmdlets.
The helpcommand display "screen of text" which means it is outputting [System.String] objects, not [PSCustomObject] objects.
Only -? will behave identically to Get-help and will provide [PSCustomObject] objects.
To see what's going on, check the different output from :
help firewall | %{ $_.GetType() }
And
Get-help firewall | %{ $_.GetType() }
And, for cmdlet,
Select-Object -? | %{ $_.gettype() }
I’ve got a few functions that return an array of PsCustomObjects, and returning other stuff would be bad.
Yet, at times, I’d like to pass in -Verbose and spit out some information to the host (using Write-Host). I can easily implement Test-Verbose, but when I want to spit out a table (with Format-Table), it’s not as easy as capturing the output and piping it to Write-Host.
What is the right way to show the output of Format-Table to the host, without sending it to the stdout, where it will be tallied as part of the function’s return values?
For example:
$objects | Format-Table | Write-Host
Thanks!!
You should be able to do this with Out-String. For example, change you example to:
$objects | Format-Table | Out-String | Write-Host
Does that work?
I am running the below Powershell command in order to get the resource usage of each VM.
Measure-VM -Name * | select-object -property VMName, MeteringDuration, AverageProcessorUsage, AverageMemoryUsage, TotalDiskAllocation
My concern is that the result set is being returned as rows instead of having each properties as columns.
RESULT
VMName
MeteringDuration
...
...
EXPECTATION
VMName MeteringDuration ... ...
Since I want to copy the results into excel, I was hoping there's a way to mitigate this. Thanks in advance for the help!
PowerShell will make a best guess at the format when it displays output. If you're exporting to Excel, CSV, any other format, what you see on the screen plays no part at all.
That is, if you have this in the console:
Get-Thing
Property1: one
Property2: two
Property3: three
Running this will still be perfectly normal:
Get-Thing | Export-Csv Things.csv
Just avoid trying to build a file using Format-* and redirect and all will be well.
I am trying to append output to a .txt file. My command is as follows:
ni C:\example\example.txt -type file -value "`n$(Get-Date)"|out-null
$CSVvariable | sort Property | Format-Table | Tee-Object -Append -FilePath C:\example\example.txt
When I run the command I get the following output in the .txt file:
《⼹㔰㈯″㤱㐺㨹
(The table is being presented correctly.)
$(Get-Date) seems to become the above symbols. Anyone have an idea why ?
Thanks in advance.
You don't really want to use format-table inside a pipeline like this. The output of format-table is a collection of "formatting objects" that the host interprets and are pretty much incomprehensible. The last time I checked, they weren't even documented well.
If you really want the table formatting, you can try adding out-string to the pipeline before the tee-object, but at that point you'll have a collection of strings, not "objects".
That's a separate issue from why you got strange characters, but I'd try removing the format-table and see how the file looks.
What is your CultuerInfo?
([System.Threading.Thread]::CurrentThread.CurrentCulture).DateTimeFormat
It seems like it might be set to something other than en-US.
I am sorting a large directory of files and I am trying to select individual lines from the output of an ls command and show those only, but I get weird results and I am not familiar enough with powershell to know what I'm doing wrong.
this approach works:
ls > data.txt
select-string 2012 data.txt
rm data.txt
but it seems wasteful to me to create a file just to read the data that I already have to fill into the file. I want to pipe the output directly to select-string.
I have tried this approach:
ls | select-string 2012
but that does not give me the appropriate output.
My guess is that I need to convert the output from ls into something select-string can work with, but I have no idea how to do that, or even whether that is actually the correct approach.
PowerShell is object-oriented, not pure text like cmd. If you want to get fileobjects(lines) that were modified in 2012, use:
Get-ChildItem | Where-Object { $_.LastWriteTime.Year -eq 2012 }
If you want to get fileobjects with "2012" in the filename, try:
Get-ChildItem *2012*
When you use
ls | select-string 2012
you're actually searching for lines with "2012" INSIDE every file that ls / get-childitem listed.
If you really need to use select-string on the output from get-childitem, try converting it to strings, then splitting up into lines and then search it. Like this:
(Get-ChildItem | Out-String) -split "`n" | Select-String 2012
I found another simple way to convert objects to strings:
Get-ChildItem | Out-String -stream | Select-String 2012
in this very interesting article:
http://blogs.msdn.com/b/powershell/archive/2006/04/25/how-does-select-string-work-with-pipelines-of-objects.aspx
If you wanted Select-String to work on the Monad formatted output, you'll need to get that as a string. Here is the thing to grok about
our outputing. When your command sequence emits a stream of strings,
we emit it without processing. If instead, your command sequence
emits a stream of objects, then we redirect those objects to the
command Out-Default. Out-Default looks at the type of the object and
the registered formating metadata to see if there is a default view
for that object type. A view defines a FORMATTER and the metadata for
that command. Most objects get vectored to either Format-Table or
Format-List (though they could go to Format-Wide or Format-Custom).
THESE FORMATTERS DO NOT EMIT STRINGS! You can see this for yourself
by the following: "These formating records are then vectored to an
OUT-xxx command to be rendered into the appropriate data for a
particular output device. By default, they go to Out-Host but you can
pipe this to Out-File, Out-Printer or Out-String. (NOTE: these
OUT-xxx commands are pretty clever, if you pipe formating objects to
them, they'll render them. If you pipe raw object to them, they'll
first call the appropriate formatter and then render them.)