Powershell Write-host outputting parameters in variable as string

powershell

$mycolorparams = "-foregroundcolor red -backgroundcolor black"

write-host "I want this foreground in Red and background in black" $mycolorparams

Hi All,

This is driving me nuts. When I use write-host the cmdlet returns everything as string:

"I want this foreground in Red and background in black -foregroundcolor red -backgroundcolor black".

Not the actual string with red text and a black background.

The worst part is this was working for me until I changed the var name in my code. I have no idea what has been altered since. I suspect it has something to do with the quotes as single quotes spit out the string and double quotes read the var. But after trying heaps of variations with single and double on both the text and var the results are the same just a string output.

I have been trawling the web for the past hour with no luck, plenty of examples but nothing I can find with the specific problem. Any help appreciated, thanks.

Best Answer

Hmm.. I have a little workaround for you in shape of a wrapper function:

$mycolorparams = " -foregroundcolor red -backgroundcolor black"
function redBlack($text){
    invoke-expression ("write-host " + $text + $mycolorparams)
}

Then execute

redBlack "I want this foreground in Red and background in black"

which will yield a correctly coloured result.

Related Solutions

Powershell – How to pass multiple parameters into a function in PowerShell

Parameters in calls to functions in PowerShell (all versions) are space-separated, not comma separated. Also, the parentheses are entirely unneccessary and will cause a parse error in PowerShell 2.0 (or later) if Set-StrictMode -Version 2 or higher is active. Parenthesised arguments are used in .NET methods only.

function foo($a, $b, $c) {
   "a: $a; b: $b; c: $c"
}

ps> foo 1 2 3
a: 1; b: 2; c: 3

Powershell – How to execute an arbitrary native command from a string

Invoke-Expression, also aliased as iex. The following will work on your examples #2 and #3:

iex $command

Some strings won't run as-is, such as your example #1 because the exe is in quotes. This will work as-is, because the contents of the string are exactly how you would run it straight from a Powershell command prompt:

$command = 'C:\somepath\someexe.exe somearg'
iex $command

However, if the exe is in quotes, you need the help of & to get it running, as in this example, as run from the commandline:

>> &"C:\Program Files\Some Product\SomeExe.exe" "C:\some other path\file.ext"

And then in the script:

$command = '"C:\Program Files\Some Product\SomeExe.exe" "C:\some other path\file.ext"'
iex "& $command"

Likely, you could handle nearly all cases by detecting if the first character of the command string is ", like in this naive implementation:

function myeval($command) {
    if ($command[0] -eq '"') { iex "& $command" }
    else { iex $command }
}

But you may find some other cases that have to be invoked in a different way. In that case, you will need to either use try{}catch{}, perhaps for specific exception types/messages, or examine the command string.

If you always receive absolute paths instead of relative paths, you shouldn't have many special cases, if any, outside of the 2 above.

Best Answer

Related Solutions

Powershell – How to pass multiple parameters into a function in PowerShell

Powershell – How to execute an arbitrary native command from a string

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