I want to write a powershell ps1 script, which needs 2 argument sets,(-a -d) and each can have upto n attributes. How to implement that?
example : DoTheTask -a <task name 1> <task name 2> ... -d <machine name 1> <machine name 2>...
You can do this:
param(
[string[]]$a,
[string[]]$d
)
write-host $a
write-host ----
write-host $d
Then you can call DoTheTask -a task1,task2 -d machine1,machine2
Can you organize your task names and machines names in such a way that they can be put in to a single string with delimiters.
In other words, could your -a argument be a string a comma-separated task names and your -d argument be a string of comma-separated machine names? If so, then all you need to do is parse the string into its components at the start of your script.
If you are passing these arguments to the script itself, you could leverage the $args internal variable, though key/value mapping will be a little trickier since PowerShell will interpret each statement as an argument. I suggest (like others) that you use another separator so that you can do the mappings easier.
Nonetheless, if you want to continue doing it this way, you can use a function like the below:
Function Parse-Arguments {
$_args = $script:args # set this to something other than $script:args if you want to use this inside of the script.
$_ret = #{}
foreach ($_arg in $_args) {
if ($_arg.substring(0,1) -eq '-') {
$_key = $_arg; [void]$foreach.moveNext() # set the key (i.e. -a, -b) and moves to the next element in $args, or the tasks to do for that switch
while ($_arg.substring(0,1) -ne '-') { # goes through each task until it hits another switch
$_val = $_arg
switch($_key) {
'-a' {
write-host "doing stuff for $_key"
$ret.add($_key,$_val) # puts the arg entered and tasks to do for that arg.
}
# put more conditionals here
}
}
}
}
}
Related
i m writing a script that makes use of a cmdlet from a console app, let's call the cmdlet as cmdA. I have no control over implementation of cmdA. cmdA takes parameters with a double dash (cmdA --param1 value1 --param2 value2 --param3 value3 --param4 value4 --param5 value5)
Now param2, param3, param4 and param5 are optional. The user of my script may or may not provide values for these optional parameters. In the script, i formed a hashtable using the parameters for which the user provided values. Let's call it paramHashtable.
I am executing cmdA #paramHashtable but this is not working. I think it has to do something with double dashes because this approach works fine with a cmd that takes parameters with single dash
What would be an efficient way to pass parameters to the cmdA (an inefficient way would be to use many if blocks to check which values were provided and make calls accordingly)
edited*
This is how i m creating the hashtable :-
$optionalParameters = #{}
$optionalParameters = ParameterSelection ${OutputFolder} ${PerfQueryIntervalInSec} ${StaticQueryIntervalInSec} ${NumberOfIterations}
$requiredParameters = #{"sqlConnectionStrings " = "$SqlConnectionStrings"}
$parameters = $requiredParameters + $optionalParameters
function ParameterSelection ([string] $outputFolder, [string] $perfQueryIntervalInSec, [string] $staticQueryIntervalInSec, [string] $numberOfIterations)
{
$parametersList = #{}
if($outputFolder -ne "")
{
$parametersList["outputFolder "] = $outputFolder
}
if($perfQueryIntervalInSec -ne "")
{
$parametersList["perfQueryIntervalInSec "] = $perfQueryIntervalInSec
}
if($staticQueryIntervalInSec -ne "")
{
$parametersList["staticQueryIntervalInSec "] = $staticQueryIntervalInSec
}
if($numberOfIterations -ne "")
{
$parametersList["numberOfIterations "] = $numberOfIterations
}
return $parametersList
}
This is how i m calling it :-
& $ExePath actionName #parameters
The $ExePath has the path of the program to be executed
The actionName takes parameters like this:-
actionName --sqlConnectionStrings "Data Source=Server1" --outputFolder C:\Output
Can splatting with hash table work on cmdlets / functions where it's parameter have dashes?
It may work, but it is definitely not a good idea to have parameter names with dashes as this will result in a function / cmdlet where named parameters cannot be used, PowerShell binds the arguments positionally! (thanks mklement0 for pointing this out):
function Test-Splatting {
param(${-param1}, ${-param2})
"${-param1} ${-param2}"
}
$param = #{ '--param1' = 'hello'; '--param2' = 'world' }
Test-Splatting #param # => hello world
Example of what was mentioned before using the same function above:
# --param1 is bound positionally and not interpreted as a parameter:
Test-Splatting --param1 hello # => --param1 hello
As for an external programs, the linked answer in comments explains very well the approach you could take using a wrapper function and the use of the automatic variable $args:
function myfunc {
$binaryPath = 'path/to/file.exe'
& $binaryPath actionName $args
# or #args we can't be sure until testing
}
myfunc --sqlConnectionStrings "Data Source=Server1" --outputFolder C:\Output
As noted in the comments, because you are calling an external program, you should use array-based splatting or simply arrays directly to pass programmatically constructed arguments.
By contrast, hashtable-based splatting is usually only helpful when calling PowerShell commands (while it technically works with external programs too, the resulting parameter format (e.g. -foo:bar or -foo:"bar none") is unusual and understood by few external programs)
Note that the parameter names and values must be passed as separate array elements and the elements representing parameter names must include the - or -- prefix; e.g., consecutive array elements
'--sqlConnectionStrings' (the name) and
'Data Source=Server1' (the value).
PowerShell then constructs a command line for invocation of the external program behind the scenes, space-separating the array elements and double-quoting elements with embedded spaces on demand; the above example turns into the following:
--sqlConnectionStrings "Data Source=Server1"
Note that it is up to the target program to parse the single string that is its command line in a way that recognizes parameter name-value pairs.
# Get the array of *optional* parameter names and values from your helper function.
$optionalParameters = ParameterSelection ${OutputFolder} ${PerfQueryIntervalInSec} ${StaticQueryIntervalInSec} ${NumberOfIterations}
# Declare the *required* parameter(s) as an array.
$requiredParameters = '--sqlConnectionStrings', $SqlConnectionStrings
# Pass the arrays as-is to the external program.
# (Empty arrays are effectively ignored.)
& $ExePath actionName $requiredParameters $optionalParmeters
Your ParameterSelection function can be simplified as follows:
function ParameterSelection ([string] $outputFolder, [string] $perfQueryIntervalInSec, [string] $staticQueryIntervalInSec, [string] $numberOfIterations)
{
# Loop over all bound parameters.
$PSBoundParameters.GetEnumerator() | ForEach-Object {
# Emit the parameter name prefixed with '--' and the value.
# PowerShell automatically collects the output strings in an array
# when you assign a call to this function to a variable.
'--' + $_.Key
$_.Value
}
}
I need to pass the variable of type map from terraform to powershell userdata script and be able to access the key value pairs of the map in the powershell script. Thank you
userdata.tf
data "template_file" "user_data" {
template = "${file("${path.module}/init.ps1")}"
vars = {
environment = var.env
# I want to pass the values as shown below
hostnames = {"dev":"devhost","test":"testhost","prod":"prodhost"}
}
}
init.ps1
$hostnames = "${hostnames}"
$environment = "${environment}"
if ($environment -eq "dev"){
# print the value of the dev key in the hostname map here
}
The template_file data source is discouraged.
Note In Terraform 0.12 and later, the templatefile function offers a built-in mechanism for rendering a template from a file. Use that function instead, unless you are using Terraform 0.11 or earlier.
The templatefile function is preferred which is why my solution uses it instead.
In either case, only map(string) is supported for template vars. The values must be strings. JSON can encode arbitrary tree structures, including your map of hostnames as strings.
In your terraform code, encode your hostnames to JSON with jsonencode.
userdata.tf:
locals {
user_data = templatefile("${path.module}/init.ps1" ,{
environment = var.env
# I want to pass the values as shown below
hostnames = jsonencode({"dev":"devhost","test":"testhost","prod":"prodhost"})
})
}
In your PowerShell, decode your hostnames from JSON with the ConvertFrom-Json cmdlet.
init.ps1:
$hostnames = '${hostnames}' | ConvertFrom-Json
$environment = "${environment}"
if ($environment -eq "dev"){
# print the value of the dev key in the hostname map here
}
Update: As noted in the comments, -AsHashtable won't necessarily work as it was added in PowerShell 6.0. Windows 10 and Windows Server 2016 include PowerShell 5.1. If you have maps with case-only differences in keys ({"name" = "foo" ; "Name" = "bar"}) then you will need to install PowerShell 6.0 or later and use ConvertFrom-Json -AsHashtable.
In order to include a collection value in a template result you must decide how you want to represent it as a string, because template results are always strings.
PowerShell supports JSON encoding via the ConvertFrom-Json cmdlet, so a JSON string might be a good candidate, although it presents some challenges because you must ensure that the JSON string is written into the result as a valid PowerShell expression, which means we must also apply PowerShell escaping.
Putting that all together, you can adjust the template like this:
$hostnames = '${replace(jsonencode(hostnames), "'", "''")}' | ConvertFrom-Json
$environment = '${replace(environment, "'", "''")}'
if ($environment -eq "dev"){
Write-Output $hostnames["dev"]
}
The jsonencode function produces a JSON-encoded version of the given value. The above then passes that result to replace so that any ' characters in the result will be escaped as '', which then allows placing the entire result in single quotes ' to ensure valid PowerShell syntax.
The result of rendering the template would be something like this:
$hostnames = '{"dev":"devhost","test":"testhost","prod":"prodhost"}' | ConvertFrom-Json -AsHashtable
$environment = 'dev'
if ($environment -eq "dev"){
Write-Output $hostnames["dev"]
}
You seem to be using Terraform 0.12, so you should use the templatefile function instead of the template_file data source. The function is better because it can accept values of any type, whereas the data source can only accept string values (because it is designed for Terraform 0.11).
To use templatefile, find the place where you were previously referring to data.template_file.user_data and use the templatefile function there instead:
templatefile("${path.module}/init.ps1", {
environment = var.env
hostnames = {"dev":"devhost","test":"testhost","prod":"prodhost"}
})
You can then remove the data "template_file" "user_data" block, because this templatefile function call replaces it.
I need help understanding how to pass on an argument from an imported module.
The module contains some custom arguments such as -one, -two, -three
I am trying to make a GUI using the commands from the module.
eg. If "One" is selected from the drop down menu, pass through the -one command.
However when I do so (using the example below), I get the error: "A positional parameter cannot be found that accepts argument '-one'."
I can see that using the code below, it adds single quotations around the command which probably breaks it.
I know I can run an IF statement (eg if combobox.text = "one", do this), however I would prefer to use a variable instead of having to make multiple if statements or a loop. The use of a variable seems like a simpler option.
I'm learning this language as I go so I'm not quite there yet with the knowledge :)
Thanks for any help. Hope this made sense.
$variable = $comboboxNumbers.Text
#example One is selected from the dropdown
Custom-ADCommand -identity "username" $variable
Below is simple example method:
function Set-SwitchParams {
[CmdletBinding()]
param (
# Parameter help description
[Parameter(Mandatory = $false)]
[switch]
$SwitchA,
[Parameter(Mandatory = $false)]
[switch]
$SwitchB
)
begin {
}
process {
}
end {
if ($SwitchA){
Write-Host "SwitchA is activated"
}
if ($SwitchB){
Write-Host "SwitchB is activated"
}
}
}
Put the method in a PS1 file, e.g. SwitchPlayground.ps1. Then source the file in PowerShell via:
. .\SwitchPlayground.ps1
Afterward, you can play around with the command, e.g.:
Set-SwitchParmas -SwitchA
I'd suggest studying the following links:
about functions basic
about functions advanced
about function parameters
Hope that helps.
An If statement if probably much nicer, but its possible to create a string and then execute the string in powershell.
As a simple example take this string
$string = '#("test","hello","whats up")'
I can then execute it and use it to create an array
$array = invoke-expression $string
Which will create an array with "test", "hello" and "whats up" and store it in $array
PS C:\temp> $string = '#("test","hi","what")'
PS C:\temp> $array = Invoke-Expression $string
PS C:\temp> $array
test
hi
what
I can write the following code in javascript:
function sum(num1, num2) {
return num1 + num2;
}
and then get a value
var someNum = sum(2,5);
I would like to do the same thing in Powershell, but I read the following guide:
PowerShell also knows the return keyword; however, it follows a
different logic. In general, the purpose of return is to end the
execution of a code section and to give the control back to the parent
block.
If you add a parameter to the return statement, the value will indeed
be returned to the calling subroutine. However, this also applies for
all other statements with an output. This means that any output
produced in the function will be stored in the variable together with
the return parameter.
I want to do this for the sake of having pure functions. However, it seems doing
var someNum = sum(2,5);
is entirely redundant, when I can just call the function above, define someNum inside of it, and it will be available in the global scope.
Am I missing something or is it possible to write pure functions in Powershell that don't return everything inside the function?
A bit tangential, but here is my actual code:
function GetPreviousKeyMD5Hashes() {
$query = "SELECT Name, MD5, executed FROM [AMagicDb].[dbo].cr_Scripts";
$command = New-Object System.Data.SQLClient.SQLCommand;
$command.Connection = $connection;
$command.CommandText = $query;
try {
$reader = $command.ExecuteReader();
while ($reader.Read()) {
$key = $reader.GetString(1)
$previousScripts.Add($key) | Out-Null
}
$reader.Close();
Write-Output "$(Get-Date) Finished querying previous scripts"
}
catch {
$exceptionMessage = $_.Exception.Message;
Write-Output "$(Get-Date) Error running SQL at with exception $exceptionMessage"
}
}
and then:
$previousScripts = New-Object Collections.Generic.HashSet[string];
GetPreviousKeyMD5Hashes;
This code isn't clear to me at all - running GetPreviousKeyMD5Hashes does set $previousScripts, but this is entirely unclear to whoever modifies this after me. My only other alternative (afaik) is to have all this in line, which also isn't readable.
is entirely redundant, when I can just call the function above, define someNum inside of it, and it will be available in the global scope.
No: functions execute in a child scope (unless you dot-source them with .), so variables created or assigned to inside a function are local to it.
Am I missing something or is it possible to write pure functions in Powershell that don't return everything inside the function?
Yes: The implicit output behavior only applies to statements whose output is neither captured - $var = ... - nor redirected - ... > foo.txt
If there are statements that happen to produce output that you'd like to discard, use $null = ... or ... > $null
Note: ... | Out-Null works in principle too, but will generally perform worse, especially in earlier PowerShell versions - thanks, TheIncorrigible1.
If there are status messages that you'd like to write without their becoming part of the output, use Write-Host or, preferably Write-Verbose or, in PSv5+, Write-Information, though note that the latter two require opt-in for their output to be visible in the console.
Do NOT use Write-Output to write status messages, as it writes to the success output stream, whose purpose is to output data ("return values").
See this answer of mine for more information about PowerShell's output streams.
The equivalent of your JavaScript code is therefore:
function sum($num1, $num2) {
Write-Host "Adding $num1 and $num2..." # print status message to host (console)
$num1 + $num2 # perform the addition and implicitly output result
}
PS> $someNum = sum 1 2 # NOTE: arguments are whitespace-separated, without (...)
Adding 1 and 2... # Write-Host output was passed through to console
PS> $someNum # $someNum captured the success output stream of sum()
3
Am I missing something or is it possible to write pure functions in Powershell that don't return everything inside the function?
You can't have your cake and eat it too...
If you have no out put in your function, then it is "pure" like you desire. If you have output, that also becomes part of the return.
You can use [ref] params. See below for example.
function DoStuff([ref]$refObj)
{
Write-Output "DoStuff: Enter"
$refObj.Value += $(1 + 2)
$refObj.Value += "more strings"
Write-Output "DoStuff: Exit"
}
$refRet = #()
$allRet = DoStuff([ref]$refRet)
"allRet"
$allRet
"refRet"
$refRet
"`n`nagain"
$allRet = DoStuff([ref]$refRet)
"allRet"
$allRet
"refRet"
$refRet
Note: Powershell doesn't need semicolons at the end of each statement; only for separating multiple statements on the same line.
Whenever possible, it's a good idea to avoid changing global state within a function. Pass input as parameters, and return the output, so you aren't tied to using the function in only one way. Your sample could look like this:
function sum
{
param($num1,$num2)
return $num1+$num2
}
$somenum=sum 2 5
Now, with Powershell, the return statement isn't needed. The result of every statement that isn't otherwise assigned, captured, redirected, or otherwise used, is just thrown in with the return value. So we could replace the return statement above with simply
$num1+$num2
You're already making use of this in your code with:
$previousScripts.Add($key) | Out-Null
where you are discarding the result of .Add(). Otherwise it would be included in the return value.
Personally, I find using return to explicitly mark the return value makes it easier to read. Powershell's way of putting all if the output in the return caused a lot of trouble for me as I was learning.
So, the only fixes to your code I would make are:
Move $previousScripts = New-Object Collections.Generic.HashSet[string] to inside the function, making it local.
Add return $previousScripts to the end of the function.
Is there a PowerShell command to list all previously loaded variables?
I am running some PowerShell scripts in Visual Studio and would like to list all variables that are available in the current PowerShell session.
I have tried the command:
ls variable:*;
But it returns the following:
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
System.Management.Automation.PSVariable
ls variable:* should work, or Get-Variable. If these are resulting in bad output, it's due to a poorly-implemented host, not with powershell itself. If you open the standard console host (run powershell.exe), you will see that these work fine.
If you need to work around a bad host, you might have better luck dumping everything to explicit strings:
Get-Variable | Out-String
or
Get-Variable |%{ "Name : {0}`r`nValue: {1}`r`n" -f $_.Name,$_.Value }
Interestingly, you can just type variable, and that works too!
I figured this out because I was curious as to what ls variable:* was doing. Get-Help ls tells us that it's an alias for PowerShell's Get-ChildItem, which I know will list all of the children of an Object. So, I tried just variable, and voila!
Based on this and this, it seems that what ls variable:* is doing is telling it to do some sort of scope/namespace lookup using the * (all/any) wildcard on the variable list, which, in this case, seems extraneous (ls variable:* == ls variable: == variable).
I frequently noodle around, testing concepts in an interactive shell, but sometimes forget my variable names or what-all I have defined.
Here is a function I wrote to wrap Get-Variable, automatically excluding any globals that were defined when the shell started up:
function Get-UserVariable()
{
[CmdletBinding()]
param(
[Parameter(Position = 0,ValueFromPipeline=$True,ValueFromPipelineByPropertyName=$True)][String[]]$Name,
[Parameter()][Switch]$ValueOnly,
[Parameter()][String[]]$Include,
[Parameter()][String[]]$Exclude,
[Parameter()][String]$Scope
)
$varNames = $global:PSDefaultVariables + #("PSDefaultVariables")
$gvParams = #{'Scope' = "1"}
if ($PSBoundParameters.ContainsKey('Name'))
{
$gvParams['Name'] = $Name
}
if ($PSBoundParameters.ContainsKey('ValueOnly'))
{
$gvParams['ValueOnly'] = $ValueOnly
}
if ($PSBoundParameters.ContainsKey('Include'))
{
$gvParams['Include'] = $Include
}
if ($PSBoundParameters.ContainsKey('Exclude'))
{
# This is where the magic happens, folks
$gvParams['Exclude'] = ($Exclude + $varNames) | Sort | Get-Unique
}
else
{
$gvParams['Exclude'] = $varNames
}
if ($PSBoundParameters.ContainsKey('Scope'))
{
$gvParams['Scope'] = $Scope
}
gv #gvParams
<#
.SYNOPSIS
Works just like Get-Variable, but automatically excludes the names of default globals.
.DESCRIPTION
Works just like Get-Variable, but automatically excludes the names of default globals, usually captured in the user's profile.ps1 file. Insert the line:
$PSDefaultVariables = (Get-Variable).name |% { PSEscape($_) }
...wherever you want to (either before, or after, any other stuff in profile, depending on whether you want it to be excluded by running this command.)
.PARAMETER Name
(Optional) Refer to help for Get-Variable.
.PARAMETER ValueOnly
(Optional) Refer to help for Get-Variable.
.PARAMETER Include
(Optional) Refer to help for Get-Variable.
.PARAMETER Exclude
(Optional) Refer to help for Get-Variable; any names provided here will be added to the existing list stored in $PSDefaultVariables (sorted / unique'd to eliminate duplicates.)
.PARAMETER Scope
(Optional) Refer to help for Get-Variable. The only asterisk here is that the default value is "1" just to get us out of this function's own scope, but you can override with whatever value you need.
.OUTPUTS
Refer to help for Get-Variable.
.EXAMPLE
PS> $foo = 1,2,3
PS> Get-UserVariable
Name Value
---- -----
foo {1, 2, 3}
#>
}
Set-Alias -Name guv -Value Get-UserVariable
Put the following line somewhere in your profile.ps1 file, either at the very top or very bottom, depending on whether you want to automatically exclude any other variables that get defined every time you run an interactive shell:
# Remember the names of all variables set up to this point (used by Get-UserVariable function)
$PSDefaultVariables = (Get-Variable).name
Hope this is helpful!