How to use the command 'pwsh' (with examples)

PowerShell, invoked using the pwsh command, is a command-line shell and scripting language designed primarily for system administration. It provides a robust framework for automating tasks, managing systems at scale, and executing scripts across multiple platforms. The pwsh command specifically refers to PowerShell 6 and above, often known as PowerShell Core, which is cross-platform and can be run on Windows, macOS, and Linux. This contrasts with the legacy Windows PowerShell, which is specific to Windows.

Use case 1: Start an interactive shell session

Code:

pwsh

Motivation: Starting an interactive shell session allows a user to execute commands and scripts dynamically, inspect variables, and manipulate data in real-time. This interactive mode is essential for tasks that require iterative testing and experimentation.

Explanation: The pwsh command with no additional arguments launches an interactive shell session. This mode allows for live execution of commands where users can type in commands one at a time and receive instant feedback.

Example Output:

PS /home/user> _

Use case 2: Start an interactive shell session without loading startup configs

Code:

pwsh -NoProfile

Motivation: Sometimes, users want a clean session without any preloaded scripts or configuration settings that might alter the shell environment. Using the -NoProfile option is crucial for diagnosing issues or running scripts in a controlled environment without interference from user profiles.

Explanation: The -NoProfile argument tells PowerShell not to load profile scripts. This keeps your environment pure and prevents any potential conflicts from personalized settings or scripts that automatically run on startup.

Example Output:

PS /home/user> _

Use case 3: Execute specific commands

Code:

pwsh -Command "echo 'powershell is executed'"

Motivation: This use case is perfect for users who wish to execute a single or a series of PowerShell commands on the fly without entering the full shell session. It helps automate small tasks directly from the command line or scripts of another language.

Explanation: The -Command argument allows the execution of commands as a string. In this example, the echo command outputs the phrase ‘powershell is executed’, demonstrating how simple tasks can be automated efficiently.

Example Output:

powershell is executed

Use case 4: Execute a specific script

Code:

pwsh -File path/to/script.ps1

Motivation: By executing a script file directly, users can automate repetitive tasks and complex workflows outlined in PowerShell scripts. This approach simplifies the execution process and ensures consistency and reproducibility of tasks.

Explanation: The -File argument is used to specify a path to a PowerShell script file (.ps1). PowerShell will run the commands stored in this script file, making it an effective way to handle pre-written automation tasks.

Example Output:

<Output contingent on script contents>

Use case 5: Start a session with a specific version of PowerShell

Code:

pwsh -Version version

Motivation: As new versions of PowerShell are released, some scripts or commands may need to be executed with specific versions to ensure compatibility. This command is essential for environments where version control is critical.

Explanation: The -Version argument specifies that the session should be started with a particular version of PowerShell. This helps ensure that any version-specific features or syntax are supported during execution.

Example Output:

<Launches specified version or errors if unavailable>

Use case 6: Prevent a shell from exit after running startup commands

Code:

pwsh -NoExit

Motivation: Running startup commands and then staying in the shell can be useful for testing startup behavior or for automating setups followed by manual interaction.

Explanation: The -NoExit argument keeps the PowerShell session open even after executing initial startup commands. This facilitates continued interactive use after initial setup.

Example Output:

PS /home/user> _

Use case 7: Describe the format of data sent to PowerShell

Code:

pwsh -InputFormat Text|XML

Motivation: Specifying the input format ensures the shell interprets input data correctly, especially when receiving complex data structures from other processes or applications.

Explanation: The -InputFormat argument determines the format of the incoming data. Either Text or XML can be chosen depending on the data source and requirements, ensuring accurate data interpretation.

Example Output:

<Depends on whether Text or XML data is processed>

Use case 8: Determine how an output from PowerShell is formatted

Code:

pwsh -OutputFormat Text|XML

Motivation: Manipulating the output format ensures that data is presented in an understandable or required format for further processing or reporting.

Explanation: Similar to input, the -OutputFormat argument determines whether the PowerShell commands’ output should be in plain Text or XML format, aiding in integration with various other systems and processes.

Example Output:

<Formatted output contingent on Script or Command>

Conclusion:

PowerShell via the pwsh command offers diverse capabilities for executing scripts and managing systems across platforms. Understanding the various command options and arguments enhances users’ ability to automate, test, and optimize tasks effectively, making PowerShell an indispensable tool in the realm of modern IT and DevOps practices.