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PSScriptAnalyzer - GitHub

Configuration in MegaLinter

Variable Description Default value
POWERSHELL_POWERSHELL_ARGUMENTS User custom arguments to add in linter CLI call
Ex: -s --foo "bar"
Ex: (src\|lib)
Include every file
Ex: (test\|examples)
Exclude no file
- file: Calls the linter for each file
- list_of_files: Call the linter with the list of files as argument
- project: Call the linter from the root of the project
POWERSHELL_POWERSHELL_FILE_EXTENSIONS Allowed file extensions. "*" matches any extension, "" matches empty extension. Empty list excludes all files
Ex: [".py", ""]
[".ps1", ".psm1", ".psd1", ".ps1xml", ".pssc", ".psrc", ".cdxml"]
POWERSHELL_POWERSHELL_FILE_NAMES_REGEX File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files
Ex: ["Dockerfile(-.+)?", "Jenkinsfile"]
Include every file
POWERSHELL_POWERSHELL_PRE_COMMANDS List of bash commands to run before the linter None
POWERSHELL_POWERSHELL_POST_COMMANDS List of bash commands to run after the linter None
POWERSHELL_POWERSHELL_CONFIG_FILE powershell configuration file name
Use LINTER_DEFAULT to let the linter find it
POWERSHELL_POWERSHELL_RULES_PATH Path where to find linter configuration file Workspace folder, then MegaLinter default rules
POWERSHELL_POWERSHELL_DISABLE_ERRORS Run linter but consider errors as warnings false

IDE Integration

Use powershell in your favorite IDE to catch errors before MegaLinter !

IDE Extension Name Install
Visual Studio Code VsCode PowerShell extension Install in VsCode

MegaLinter Flavours

This linter is available in the following flavours

Flavor Description Embedded linters Info
all Default MegaLinter Flavor 97 Docker Image Size (tag) Docker Pulls
dotnet Optimized for C, C++, C# or VB based projects 49 Docker Image Size (tag) Docker Pulls

Behind the scenes

How are identified applicable files

  • File extensions: .ps1, .psm1, .psd1, .ps1xml, .pssc, .psrc, .cdxml

How the linting is performed

  • powershell is called one time by identified file

Example calls

pwsh -NoProfile -NoLogo -Command "Invoke-ScriptAnalyzer -EnableExit -Path myfile.ps1"
pwsh -NoProfile -NoLogo -Command "Invoke-ScriptAnalyzer -EnableExit -Settings .powershell-psscriptanalyzer.psd1 -Path myfile.ps1"

Help content

Usage: pwsh[.exe] [-Login] [[-File] <filePath> [args]]
                  [-Command { - | <script-block> [-args <arg-array>]
                                | <string> [<CommandParameters>] } ]
                  [-ConfigurationName <string>] [-CustomPipeName <string>]
                  [-EncodedCommand <Base64EncodedCommand>]
                  [-ExecutionPolicy <ExecutionPolicy>] [-InputFormat {Text | XML}]
                  [-Interactive] [-MTA] [-NoExit] [-NoLogo] [-NonInteractive] [-NoProfile]
                  [-OutputFormat {Text | XML}] [-SettingsFile <filePath>] [-SSHServerMode] [-STA]
                  [-Version] [-WindowStyle <style>] [-WorkingDirectory <directoryPath>]

       pwsh[.exe] -h | -Help | -? | /?

PowerShell Online Help

All parameters are case-insensitive.

-File | -f

    If the value of File is "-", the command text is read from standard input.
    Running "pwsh -File -" without redirected standard input starts a regular
    session. This is the same as not specifying the File parameter at all.

    This is the default parameter if no parameters are present but values are
    present in the command line. The specified script runs in the local scope
    ("dot-sourced"), so that the functions and variables that the script
    creates are available in the current session. Enter the script file path
    and any parameters. File must be the last parameter in the command, because
    all characters typed after the File parameter name are interpreted as the
    script file path followed by the script parameters.

    Typically, the switch parameters of a script are either included or
    omitted. For example, the following command uses the All parameter of the
    Get-Script.ps1 script file: "-File .\Get-Script.ps1 -All"

    In rare cases, you might need to provide a BOOLEAN value for a switch
    parameter. To provide a BOOLEAN value for a switch parameter in the value
    of the FILE parameter, Use the parameter normally followed immediately by a
    colon and the boolean value, such as the following:
    "-File .\Get-Script.ps1 -All:$False".

    Parameters passed to the script are passed as literal strings, after
    interpretation by the current shell. For example, if you are in cmd.exe and
    want to pass an environment variable value, you would use the cmd.exe
    syntax: "pwsh -File .  est.ps1 -TestParam %windir%"

    In contrast, running "pwsh -File .  est.ps1 -TestParam $env:windir" in
    cmd.exe results in the script receiving the literal string "$env:windir"
    because it has no special meaning to the current cmd.exe shell. The
    "$env:windir" style of environment variable reference can be used inside a
    Command parameter, since there it is interpreted as PowerShell code.

    Similarly, if you want to execute the same command from a Batch script,
    you would use "%~dp0" instead of ".\" or "$PSScriptRoot" to represent the current
    execution directory: "pwsh -File %~dp0test.ps1 -TestParam %windir%". If you
    instead used ".  est.ps1", PowerShell would throw an error because it cannot
    find the literal path ".  est.ps1".

    When the script file invoked terminates with an exit command, the process
    exit code is set to the numeric argument used with the exit command. With
    normal termination, the exit code is always 0.

    Similar to -Command, when a script-terminating error occurs, the exit code
    is set to 1. However, unlike with -Command, when the execution is
    interrupted with Ctrl-C the exit code is 0.

-Command | -c

    Executes the specified commands (and any parameters) as though they were
    typed at the PowerShell command prompt, and then exits, unless the NoExit
    parameter is specified.

    The value of Command can be "-", a script block, or a string. If the value
    of Command is "-", the command text is read from standard input.

    The Command parameter only accepts a script block for execution when it can
    recognize the value passed to Command as a ScriptBlock type. This is only
    possible when running pwsh from another PowerShell host. The ScriptBlock
    type may be contained in an existing variable, returned from an expression,
    or parsed by the PowerShell host as a literal script block enclosed in
    curly braces "{}", before being passed to pwsh.

        pwsh -Command {Get-WinEvent -LogName security}

    In cmd.exe, there is no such thing as a script block (or ScriptBlock type),
    so the value passed to Command will always be a string. You can write a
    script block inside the string, but instead of being executed it will
    behave exactly as though you typed it at a typical PowerShell prompt,
    printing the contents of the script block back out to you.

    A string passed to Command is still executed as PowerShell script, so the
    script block curly braces are often not required in the first place when
    running from cmd.exe. To execute an inline script block defined inside a
    string, the call operator "&" can be used:

        pwsh -Command "& {Get-WinEvent -LogName security}"

    If the value of Command is a string, Command must be the last parameter for
    pwsh, because all arguments following it are interpreted as part of the
    command to execute.

    When called from within an existing PowerShell session, the results are
    returned to the parent shell as deserialized XML objects, not live objects.
    For other shells, the results are returned as strings.

    If the value of Command is "-", the command text is read from standard
    input. You must redirect standard input when using the Command parameter
    with standard input. For example:


        "hi" |
        % { "$_ there" }

        '@ | powershell -NoProfile -Command -

    This example produces the following output:

        hi there

    The process exit code is determined by status of the last (executed)
    command within the script block. The exit code is 0 when $? is $true or 1
    when $? is $false. If the last command is an external program or a
    PowerShell script that explicitly sets an exit code other than 0 or 1, that
    exit code is converted to 1 for process exit code. To preserve the specific
    exit code, add exit $LASTEXITCODE to your command string or script block.

    Similarly, the value 1 is returned when a script-terminating
    (runspace-terminating) error, such as a throw or -ErrorAction Stop, occurs
    or when execution is interrupted with Ctrl-C.

-ConfigurationName | -config

    Specifies a configuration endpoint in which PowerShell is run. This can be
    any endpoint registered on the local machine including the default
    PowerShell remoting endpoints or a custom endpoint having specific user
    role capabilities.

    Example: "pwsh -ConfigurationName AdminRoles"


    Specifies the name to use for an additional IPC server (named pipe) used
    for debugging and other cross-process communication. This offers a
    predictable mechanism for connecting to other PowerShell instances.
    Typically used with the CustomPipeName parameter on "Enter-PSHostProcess".

    This parameter was introduced in PowerShell 6.2.

    For example:

        # PowerShell instance 1
        pwsh -CustomPipeName mydebugpipe
        # PowerShell instance 2
        Enter-PSHostProcess -CustomPipeName mydebugpipe

-EncodedCommand | -e | -ec

    Accepts a Base64-encoded string version of a command. Use this parameter to
    submit commands to PowerShell that require complex, nested quoting. The
    Base64 representation must be a UTF-16 encoded string.

    For example:

        $command = 'dir "c:\program files" '
        $bytes = [System.Text.Encoding]::Unicode.GetBytes($command)
        $encodedCommand = [Convert]::ToBase64String($bytes)
        pwsh -encodedcommand $encodedCommand

-ExecutionPolicy | -ex | -ep

    Sets the default execution policy for the current session and saves it in
    the $env:PSExecutionPolicyPreference environment variable. This parameter
    does not change the persistently configured execution policies.

    This parameter only applies to Windows computers. The
    $env:PSExecutionPolicyPreference environment variable does not exist on
    non-Windows platforms.

-InputFormat | -inp | -if

    Describes the format of data sent to PowerShell. Valid values are "Text"
    (text strings) or "XML" (serialized CLIXML format).

-Interactive | -i

    Present an interactive prompt to the user. Inverse for NonInteractive

-Login | -l

    On Linux and macOS, starts PowerShell as a login shell, using /bin/sh to
    execute login profiles such as /etc/profile and ~/.profile. On Windows,
    this switch does nothing.

    [!IMPORTANT] This parameter must come first to start PowerShell as a login
    shell. The parameter is ignored if passed in any other position.

    To set up pwsh as the login shell on UNIX-like operating systems:

    - Verify that the full absolute path to pwsh is listed under /etc/shells

      - This path is usually something like /usr/bin/pwsh on Linux or
        /usr/local/bin/pwsh on macOS
      - With some installation methods, this entry will be added
        automatically at installation time
      - If pwsh is not present in /etc/shells, use an editor to append the
        path to pwsh on the last line. This requires elevated privileges to

    - Use the chsh utility to set your current user's shell to pwsh:

        chsh -s /usr/bin/pwsh

    [!WARNING] Setting pwsh as the login shell is currently not supported on
    Windows Subsystem for Linux (WSL), and attempting to set pwsh as the
    login shell there may lead to being unable to start WSL interactively.


    Start PowerShell using a multi-threaded apartment. This switch is only
    available on Windows.

-NoExit | -noe

    Does not exit after running startup commands.

    Example: "pwsh -NoExit -Command Get-Date"

-NoLogo | -nol

    Hides the copyright banner at startup of interactive sessions.

-NonInteractive | -noni

    Does not present an interactive prompt to the user. Any attempts to use
    interactive features, like Read-Host or confirmation prompts, result in
    statement-terminating errors.

-NoProfile | -nop

    Does not load the PowerShell profiles.

-OutputFormat | -o | -of

    Determines how output from PowerShell is formatted. Valid values are "Text"
    (text strings) or "XML" (serialized CLIXML format).

    Example: "pwsh -o XML -c Get-Date"

    When called withing a PowerShell session, you get deserialized objects as
    output rather plain strings. When called from other shells, the output is
    string data formatted as CLIXML text.

-SettingsFile | -settings

    Overrides the system-wide "powershell.config.json" settings file for the
    session. By default, system-wide settings are read from the
    "powershell.config.json" in the "$PSHOME" directory.

    Note that these settings are not used by the endpoint specified by the
    "-ConfigurationName" argument.

    Example: "pwsh -SettingsFile c:\myproject\powershell.config.json"

-SSHServerMode | -sshs

    Used in sshd_config for running PowerShell as an SSH subsystem. It is not
    intended or supported for any other use.


    Start PowerShell using a single-threaded apartment. This is the default.
    This switch is only available on Windows.

-Version | -v

    Displays the version of PowerShell. Additional parameters are ignored.

-WindowStyle | -w

    Sets the window style for the session. Valid values are Normal, Minimized,
    Maximized and Hidden.

-WorkingDirectory | -wd

    Sets the initial working directory by executing at startup. Any valid
    PowerShell file path is supported.

    To start PowerShell in your home directory, use: pwsh -WorkingDirectory ~

-Help, -?, /?

    Displays help for pwsh. If you are typing a pwsh command in PowerShell,
    prepend the command parameters with a hyphen (-), not a forward slash (/).

Installation on mega-linter Docker image

  • Dockerfile commands :
# Parent descriptor install
ARG PWSH_DIRECTORY='/opt/microsoft/powershell'
RUN mkdir -p ${PWSH_DIRECTORY} \
    && curl --retry 5 --retry-delay 5 -s${PWSH_VERSION} \
        | grep browser_download_url \
        | grep linux-alpine-x64 \
        | cut -d '"' -f 4 \
        | xargs -n 1 wget -O - \
        | tar -xzC ${PWSH_DIRECTORY} \
    && ln -sf ${PWSH_DIRECTORY}/pwsh /usr/bin/pwsh

# Linter install
RUN pwsh -c 'Install-Module -Name PSScriptAnalyzer -RequiredVersion ${PSSA_VERSION} -Scope AllUsers -Force'

Example success log

Results of powershell linter (version 7.1.0)
See documentation on

[SUCCESS] .automation/test/powershell/powershell_good_1.ps1

[SUCCESS] .automation/test/powershell/powershell_good_1.psd1

[SUCCESS] .automation/test/powershell/powershell_good_1.psm1

Example error log

Results of powershell linter (version 7.1.0)
See documentation on

[ERROR] .automation/test/powershell/powershell_bad_1.ps1

    RuleName                            Severity     ScriptName Line  Message
    --------                            --------     ---------- ----  -------
    PSAvoidUsingEmptyCatchBlock         Warning      powershell 12    Empty catch b
                                                     _bad_1.ps1       lock is used.
                                                                       Please use W
                                                                      rite-Error or
                                                                       throw statem
                                                                      ents in catch
    PSAvoidTrailingWhitespace           Information  powershell 11    Line has trai
                                                     _bad_1.ps1       ling whitespa
    PSAvoidUsingUsernameAndPasswordPara Error        powershell 4     Function 'Bad
    ms                                               _bad_1.ps1       Function' has
                                                                       both Usernam
                                                                      e and Passwor
                                                                      d parameters.
                                                                       Either set t
                                                                      he type of th
                                                                      e Password pa
                                                                      rameter to Se
                                                                      cureString or
                                                                       replace the
                                                                      Username and
                                                                      Password para
                                                                      meters with a
                                                                       Credential p
                                                                      arameter of t
                                                                      ype PSCredent
                                                                      ial. If using
                                                                       a Credential
                                                                       parameter in
                                                                       PowerShell 4
                                                                      .0 or earlier
                                                                      , please defi
                                                                      ne a credenti
                                                                      al transforma
                                                                      tion attribut
                                                                      e after the P
                                                                      SCredential t
                                                                      ype attribute
    PSAvoidUsingPlainTextForPassword    Warning      powershell 5     Parameter '$P
                                                     _bad_1.ps1       assword' shou
                                                                      ld use Secure
                                                                      String, other
                                                                      wise this wil
                                                                      l expose sens
                                                                      itive informa
                                                                      tion. See Con
                                                                      String for mo
                                                                      re informatio
    PSUseDeclaredVarsMoreThanAssignment Warning      powershell 9     The variable
    s                                                _bad_1.ps1       'VariableThat
                                                                      r' is assigne
                                                                      d but never u

[ERROR] .automation/test/powershell/powershell_bad_1.psd1

    RuleName                            Severity     ScriptName Line  Message
    --------                            --------     ---------- ----  -------
    TerminatorExpectedAtEndOfString     ParseError   powershell 2     The string is
                                                     _bad_1.psd        missing the
                                                     1                terminator: '
    MissingEndCurlyBrace                ParseError   powershell 1     Missing closi
                                                     _bad_1.psd       ng '}' in sta
                                                     1                tement block
                                                                      or type defin

[ERROR] .automation/test/powershell/powershell_bad_1.psm1

    RuleName                            Severity     ScriptName Line  Message
    --------                            --------     ---------- ----  -------
    TerminatorExpectedAtEndOfString     ParseError   powershell 1     The string is
                                                     _bad_1.psm        missing the
                                                     1                terminator: "