Part 6. Getting to know PowerShell (Managing command output)

25 July 2023 15 minutes Author: Lady Liberty

PowerShell: Efficient output of commands and results

Managing Command Output in PowerShell is a complete guide for anyone who wants to work efficiently with the PowerShell shell and confidently manage command output. Using commands in PowerShell allows you to interact with the operating system, perform tasks, and obtain results. However, sometimes the output can be congested or difficult to parse. In this tutorial, we’ll look at different approaches to managing command output, such as filtering, sorting, saving results to a file, and using output streams. You will learn about the various options and functions that will allow you to easily find the information you need, control the output and save the data for use.

Regardless of your experience with PowerShell, this guide will help you streamline your work with commands, make it easier to analyze the results, and increase your productivity when working with this powerful command shell. While working in the PowerShell shell, we have not yet thought about how the system forms text lines that are displayed on the screen as a result of the execution of one or another command (recall that PowerShell cmdlets return .NET objects, which, as a rule, do not know how to display themselves on the screen). In fact, PowerShell has a database (set of XML files) that contains default formatting modules for various types of .NET objects. These modules determine which object properties are displayed during output and in which format: list or table. The formatting modules are located in the directory where PowerShell is installed (the path to this directory is stored in the $pshome environment variable), you can view their list using the following command: PS C:\> Get-Childltam $PSHCME/*format*

Command output management

While working in PowerShell, we have not yet thought about how the system generates lines of text that are displayed as a result of executing one or another command (recall that PowerShell cmdlets return . NET objects that usually cannot display themselves on the screen).

Basically, PowerShell has a database (a set that contains default formatters for various . NETTO-06EkТ0B. These modules determine which properties of the object are displayed at the output and in which format: lists and tables. Formatters are located in the directory where PowerShell is installed (the path to this directory is stored in the $PSHOME environment variable), you can view their list using the following command:

PS С:\> Get-Childltam $PSHCME/*format*
Каталог: С:\Windows\System32\WindowsPowerShell\vl.О
Mode LastWriteTime Length Name
-а--- 07.12.2019 12:10 12825 Certificate.format.pslxml
-а--- 07.12.2019 12:10 4994 Diagnostics.Format.pslxml
-а--- 07.12.2019 12:10 138013 DotNetTypes.format.pslxml
-а--- 07.12.2019 12:10 10112 Event.Format.pslxml
-а--- 07.12.2019 12:10 25306 FileSystem.format.pslxml
-а--- 07.12.2019 12:10 91655 Help.format.pslxml
-а--- 07.12.2019 12:10 138625 HelpV3.format.pslxml
-а--- 07.12.2019 12:10 206468 PowerShellCore.format.pslxml
-а--- 07.12.2019 12:10 4097 PowerShellTrace.format.pslxml
-а--- 07.12.2019 12:10 8458 Registry.format.pslxml
-а--- 07.12.2019 12:10 16598 WSMan.Format.pslxml

When an object reaches the end of the pipeline, PowerShell determines its type and looks for it in the list of objects that have a formatting rule set. If this type is found in the list, the corresponding form is applied to the object; if not, PowerShell simply displays the properties of this . NETTO-06RKTA.

You can also explicitly set formatting rules for cmdlets and, like other console programs, redirect that data to a file, printer, or empty device.

Formatting of source information

In traditional shells, commands and utilities format the output themselves. Some commands (for example, dir in the cmd.exe interpreter) allow you to customize the output format using special key parameters.

In PowerShell, the result is formatted with four special format cmdlets (Table 6.1). This makes learning easier because you don’t have to remember the tools and formatting options for other commands (the rest of the cmdlets don’t format the output).

As noted earlier, if none of the Format cmdlets is explicitly specified, the default formatter is used, which is determined by the type of data being displayed. For example, when running the Get-Service cmdlet, the default output is a table with three columns (Status, Name, and Disp1ayName):

PS С:\> Get-Service
Status Name DisplayName
Stopped Alerter
Running ALG
Stopped AppMgmt
Stopped aspnet state
Running Ati HotKey Poller
Running Audiosrv
Running BITS
Служба шлюза уровня приложения
Управление приложениями
ASP.NET State Service
Ati HotKey Poller
Windows Audio
Фоновая интеллектуальная служба пер...
Running Browser Обозреватель компьютеров
Stopped cisvc Служба индексирования
Stopped ClipSrv Сервер папки обмена
Stopped clr optimizatio.. . .NET Runtime Optimization Service v
Stopped COMSysApp Системное приложение COM+
Running CryptSvc Службы криптографии
Running DcomLaunch Запуск серверных процессов DCOM
Running Dhcp DHCP-клиент

To change the output format, you must pass it to the appropriate Fornat cmdlet. For example, using the Format-List cmdlet, the following command will list the following commands:

PS С:\> Get-Service | Format-List
: Alerter
: Оповещатель
: Stopped
: {}
: {LanmanWorkstation}
: False
CanShutdown : False
: False
: Win32ShareProcess
: Служба шлюза уровня приложения
: Running
: {}
: {}
: False
: False
: True
: Win320wnProcess

As you can see, when using the list format, more information about each service is displayed than the table format (instead of three columns of data for each service, the list format displays nine rows of data). However, this does not mean that the format list cmdlet receives additional information about the services. This information is contained in the objects returned by the Get-Service command, but the default Fomat-Tab1e cmdlet discards it because it cannot display more than three columns. When formatting the output using the Format-List and Fonnat-Tab1e cmdlets, you can specify the names of the object properties to be displayed (recall that the list of object properties can be viewed in the Get-Member cmdlet). Example:

PS С:\> Get-Service | Format-List Name, Status, CanStop
Name : Alerter
Status : Stopped
CanStop : False
Name : ALG
Status : Running
CanStop : True
Name : AppMgmt
Status : Stopped
CanStop : False
Вывести все имеющиеся у объектов свойства можно с помощью параметра *, например:
PS С:\> Get-Service Format-List *
: False
: False

Forwarding of information

There are several cmdlets in the PowerShell shell that you can use to control the output. These cmdlets start with the word Out, and you can see their list like this:

PS С:\> Get-Command out-* | Format-Table Name

By default, output is passed to the 0ut-Defau1t cmdlet, which in turn delegates all string display work to the 0ut-Host cmdlet. To understand this mechanism, it should be kept in mind that the architecture of PowerShell implies a distinction between the shell kernel itself (the command interpreter) and the host application that uses that kernel. In principle, any application that implements a number of special interfaces that allow you to correctly interpret the information received from PowerShell can act as a host. In our case, the host is a console window (terminal) in which we work with the shell, and the 0utHost cmdlet sends output information to this window.

The -Paging parameter of the Out-Host cmdlet, similar to the command of the cmd.exe interpreter, allows you to organize page-by-page display of information, for example:

PS С:\> Get-Help Get-Process -Full | Out-Host -Paging
Отображает процессы, выполняющиеся на локальном компьютере.
Get-Process [[-name] <string[]>] [<CommonParameters>]
<ПРОБЕЛ> следующая страница; <CR> следующая строка; Q выход

Saving data to a file

As mentioned, PowerShell supports redirecting the standard output stream of commands to text files using the standard > and >> operators. For example, the following command will map the contents of the root directory c:\ to the text file d:\dir c.txt (if this file exists, it will be overwritten):

PS C:\> реж. C:\ > d:\dir c.txt

If you want to redirect the output of the command to a file in append mode (while preserving the previous contents of this file), you should use the >> operator:

PS  DXR з:\ >> d: \dxr c.txt

In addition to the > and >> redirection operators, PowerShell also has a cmdlet called 0utFile that also allows you to direct output to a text file instead of a console window. At the same time, the 0ut-Fi1e cmdlet has several additional parameters with which you can more flexibly control the output: specify the file encoding type, specify the length of the output lines in characters, and select the file overwriting mode (Table 6.2).

For example, the following command will save a detailed version of the built-in help for the Windows-encoded Get-Process cmdlet to the help.txt file:

PS С:\Users\andrv> Get-Help Get-Process -Detailed | Out-File -FilePath
.\help.txt -Encoding "Default"

Print data

You can print data directly to the printer using the Out-Printer cmdlet. In this case, printing can be performed either on the default printer (no special parameters are required for this), or on an arbitrary printer (in this case, the short name of the printer must be specified as the value of the -Name parameter). Example:

PS C:\script> Get-Process | Out-Printer -Name "Xerox Phaser 3500 PCL 6"

Output suppression

Use the 0ut-Nu11 cmdlet to cancel any input. This can be useful for suppressing the display of unnecessary information received as a side effect of command execution. For example, when creating a directory with the mkdir command, its contents are displayed:

PS С:\> mkdir klop
Каталог: Microsoft.PowerShell.Core\FileSystem::С:\
Mode LastWriteTime Length Name
d--- 26.05.2020 15:01 klop
Если мы не желаем видеть эту информацию, то результат выполнения команды
mkdir нужно передать по конвейеру командлету Out-Null:
PS С:\> mkdir klop | Out-Null
PS C:\>
Как видим, в этом случае никаких сообщений на экран не выводится.

Tabular output of data in a graphic window

With the help of the 0ut-GridView cmdlet, as with Fornat-Table, you can display data in tabular form, but not in the same console window, but in a separate dialog box with a graphical interface.

For example, run the following command:

ps C: \> Get-Process Out-GridView

At the same time, information about the processes will be available in a separate window (Fig. 6.1)

The title bar of this window displays the executed PowerShell command, and if necessary, you can change the title by specifying the -Tit1e option:

PS C:\> Get-Process | Out-GridView -Title “Processes”

The displayed table can be sorted by the values of any column by clicking on its name. You can also filter rows according to various conditions using the filter designer (Fig. 6.2).

The tabular view of the data generated by Out-GridView is interactive and can be changed directly in the table itself. Moreover, the resulting set of rows obtained by sorting, filtering, and selection can be returned to PowerShell again by clicking OK and sent further down. To do this, you need to specify -PassThru. Example:

PS С:\> Get-Process 1 Out-GridView -Title "Процессы" -PassThru |
Format-Table Id, ProcessName
Fig. 6.1. Displaying data in a window with a graphical interface
Fig. 6.2. List of processes containing the word win in the name
Id ProcessName
836 wininit

In this example, the rows (objects) from the next window are passed to the Format-Table cmdlet

Fig. 6.3. Strings prepared for return to the PowerShell pipeline

The rows to be returned to the PowerShell pipeline from the dialog must be selected in the table view (by default, only the first row is returned).

Standard combinations are supported here:

  • <Ctrl>+<A> to enter all lines;

  • Hold <Shift> and the up or down arrows to select a contiguous range of lines;

  • Hold <Ctrl> and click to add individual lines

Output in HTML format

PowerShell has a standard cmdlet called ConvertTo-Htm1 that you can use  to display the output of your commands. For example, let’s use Get-PSDrive to get a list of PowerShell drives and convert the list to HTML:

PS С:\Users\andrv> Get-PSDrive I ConvertTo-Html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN”
<html xmlns="">
118 Часть I. Знакомимся с PowerShell
<title>HTML TABLE</title>
<trxtdx/tdxtdx/tdxtdx/tdxtd>Alias</tdxtd>Microsoft. PowerShell. Core\
Alias</tdxtdx/tdxtd>HwcK, содержащий представление псевдонимов, сохраненное
в состоянии сеанса. </tdxtdx/tdxtd>System.Management .Automation.
<trxtdx/tdxtdx/tdxtdx/tdxtd>WSMan</tdxtd>Microsoft.WSMan. Management\
WSMan</tdxtdx/tdxtd>KopeHb хранилища конфигурации WsMan.</tdxtdx/td>
<td>System. Management .Automation. PSCredential</tdxtdx/tdx/tr>

As you can see, the output is a correct HTML document with a table designed using the <tabie> tag. This output can be sent to an HTML file and opened in a browser (Fig. 6.4) using the invoke-item cmdlet:

PS С:\Users\andrv> Get-PSDrive | ConvertTo-Html | Out-File psdrives.html
PS C:\Users\andrv> Invoke-Item .\psdrives.html
Fig. 6.4. An HTML page with a table generated by the ConvertTo-Html cmdlet

The -As List parameter allows you to change the appearance of the table – the properties of each object will be formatted as a list (Fig. 6.5), as when formatting the output using Fomat-List:

PS С:\Users\andrv> Get-PSDrive | ConvertTo-Html -As List | Out-File
psdrives. html
PS C:\Users\andrv> Invoke-Item .\psdrives.html


Fig. 6.5. NTMI page with objects as a list

With the help of additional parameters, you can set the header text before and after the table:

PS С:\Users\andrv> Get-PSDrive | ConvertTo-Html -Title ’’Отчет о дисках
PowerShell" -PreContent "<р>Текст до таблицы</р>" -PostContent "Текст после
таблицы" | Out-File .\psdrives.html
При необходимости к формируемому HTML-документу можно подключить внешний CSS-файл, путь к которому указывается в качестве значения параметра -cssUri.
Если в convertTo-HTML указан параметр -Fragment, то в HTML-разметке будет сгенерирована только таблица с данными (тег <tabie>):
PS С:\Users\andrv> Get-PSDrive | ConvertTo-Html -Fragment
<trxtdx/tdxtdx/tdxtdx/tdxtd>Alias</tdxtd>Microsoft. PowerShell. Core\
Alias</tdxtdx/tdxtd>JJncK, содержащий представление псевдонимов, сохраненное
в состоянии сеанса. </tdxtdx/tdxtd>System.Management .Automation. PSCredential

Additional threads in PowerShell

In addition to the standard 0utput stream through which objects are passed from cmdlet to cmdlet, PowerShell supports several other streams.

The presence of several continuous chains does not clutter the main flow with errors or other additional messages – cmdlets receive only the necessary structured objects as input.

You can write data to different threads using the corresponding cmdlets using the Write verb: Write-Output, Write-Error, Write-Warning, WriteVerbose, Write-Debug, and Write-Information.

For example, let’s write a new message in the error stream:

PS С:\Users\andrv> Write-Error -Message "Произошла ошибка"
Write-Error -Message "Произошла ошибка" : Произошла ошибка
+ Categoryinfo : NotSpecified: (:) [Write-Error], WriteErrorException
+ FullyQualifiedErrorld : Microsoft.PowerShell.Commands.WriteErrorException

This automatically generated an object with error information and placed it in the error stream (we’ll talk more about error detection and handling in PowerShell in Chapter 10). Error information from the error stream is also displayed and highlighted in red.

Information from the Verbose stream is displayed in the console and is highlighted in yellow only if the -Verbose parameter is specified when calling the command:

PS С: \Users\andrv> Write-Verbose -Message "Сообщение из потока Verbose"
PS С:\Users\andrv> Write-Verbose -Message "Сообщение из потока Verbose"
ПОДРОБНО: Сообщение из потока Verbose
Поведение (в частности, режим вывода на экран сообщений) команд write-* зависит от значений нескольких системных переменных:
PS С:\Users\andrv> $ErrorActionPreference
PS C:\Users\andrv> $DebugPreference
PS C:\Users\andrv> $VerbosePreference
PS C: \Users\andrv> $InforrnationPreference

If the value of the variable Si1entlyContinue, then the information from the corresponding stream is not duplicated on the screen. For additional PowerShell streams, redirection to a file or to the standard output stream 0utput is also supported.

Redirect to file

You can redirect data from a stream to a file using the same > and >> operators, preceded by a numeric stream number. Example:

PS С:\Users\andrv> Write-Error -Message "Произошла ошибка" 2> error.txt
PS С:\Users\andrv> Get-Content .\error.txt
Write-Error -Message "Произошла ошибка" 2> error.txt : Произошла ошибка
+ Categoryinfo : NotSpecified: (:) [Write-Error], WriteErrorException
+ FullyQualifiedErrorld : Microsoft.PowerShell.Commands.WriteErrorException
PS C: \Users\andrv> Write-Warning -Message "Сообщение из потока Warning" 3>
PS C:\Users\andrv> Get-Content .\l.txt
Сообщение из потока Warning
Также с помощью оператора *> можно перенаправить в один файл все данные из 
всех потоков. Например, выполним блок кода, в котором идет запись в потоки
Output, warning и Error, и перенаправим данные из всех этих потоков в файл
PS С:\Users\andrv> & { Write-Output "Данные из Output"
» Write-Warning "Данные из Warning"
» Write-Error "Данные из Error"
» } *> streams.txt
PS С:\Users\andrv> Get-Content .\streams.txt
Данные из Output
Данные из Warning
Write-Output "Данные из Output"
Write-Warning "Данные из Warning"
Write-Error "Данные из Error"
: Данные из Error
строка:1 знак:1
+ & { Write-Output "Данные из Output"
+ Categoryinfo : NotSpecified: (:) [Write-Error], WriteErrorException
+ FullyQualifiedErrorld : Microsoft.PowerShell.Commands.WriteErrorException

Redirect to the output stream 0utput

You can redirect data from a stream numbered n n to the standard output stream 0utput, which is numbered 1, using For example, let’s try saving data from a Verbose stream:

PS С:\Users\andrv> $message = Write-Verbose -Message "Подробное сообщение"
ПОДРОБНО: Подробное сообщение
Проверим значение переменной $message:
PS С:\Users\andrv> $message
Как видим, в $message ничего не записалось, т. к. оператор присваивания получает
данные ИЗ ВЫХОДНОГО потока Output, а не ИЗ потока Verbose.
Перенаправим теперь поток verbose с номером 4 в выходной поток output (номер 1):
PS С:\Users\andrv> $message = Write-Verbose -Message "Подробное сообщение"
-Verbose 4>&1
После ЭТОГО переменная $message будет иметь ТИП System.Management.Automation.
verboseRecord, в ней будет содержаться наше сообщение:
PS С:\Users\andrv> $message
ПОДРОБНО: Подробное сообщение
PS С:\Users\andrv> $message.getType().fullName


  • PowerShell uses an internal formatting system that determines the appearance and content of object information that is displayed on the screen. Formatting rules can be set explicitly using cmdlets

  • By default, the data is displayed on the screen, using the 0ut-* cmdlets, the output can be redirected to a file, to a printer, or to an empty device. Use the Out-GridView cmdlet to display the data table in a separate GUI dialog box.

  • The output of the commands can be formatted with ConvertTo-HTM1.

  • PowerShell supports several independent threads to display additional information on them that is not needed in the main thread that provides the flow of objects along the pipeline. Data from these additional streams can be redirected to a file or to the standard output stream 0utput.

Thanks to our team of volunteers for providing information from open sources.

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