Execute “real life” command line from variable in Powershell

Question

When I for example read some uninstall string from the registry like \"C:\\Program Files (x86)\\Opera\\Launcher.exe\" /uninstall I can copy it to the Powershell

Answer 1

In order to use & (or direct invocation if the command name/path is an unquoted literal), the command name/path must be passed separately from its arguments.
When invoking an external program, you may pass these arguments as an array.

The solution below leverages PowerShell's own Write-Output cmdlet in combination with a - safe - invocation of Invoke-Expression^[1] in order to parse the string into its constituent arguments.

# Gets the arguments embedded in the specified string as an array of literal tokens 
# (applies no interpolation). 
# Note the assumption is that the input string contains no NUL characters 
# (characters whose code point is `0x0`) - which should be a safe assumption
# Example: 
#   get-EmbeddedArguments '"C:\Program Files (x86)\Opera\Launcher.exe" /uninstall'
# yields array @( 'C:\Program Files (x86)\Opera\Launcher.exe', '/uninstall' )
function get-EmbeddedArguments ([string] $String) {
  (Invoke-Expression "Write-Output -- $($String -replace '\$', "`0")") -replace "`0", '$'            #"
}

# Input string.
$var = '"C:\Program Files (x86)\Opera\Launcher.exe" /uninstall'

# Extract the command name (program path) and arguments.
# Note the destructuring assignment that stores the return array's 1st element
# in $exe, and collects the remaining elements, if any, in $exeArgs.
$exe, $exeArgs = get-EmbeddedArguments $var

# Use & to invoke the command (name / program path) ($exe) and pass
# it all arguments as an array.
& $exe $exeArgs

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^{[1] Invoke-Expression should generally be avoided, as Bill points out, because it presents a security risk and there are typically safer and more robust options available. Here, however, there is no simple alternative, and the security risk is avoided by temporarily replacing all $ instances in the input string so as to prevent unintended string interpolation.}