Question

In my script I’m about to run a command

pandoc -Ss readme.txt -o readme.html

But I’m not sure if pandoc is installed. So I would like to do (pseudocode)

if (pandoc in the path)
{
    pandoc -Ss readme.txt -o readme.html
}

How can I do this for real?

Answer 1

You can test through Get-Command (gcm)

if (Get-Command "pandoc.exe" -ErrorAction SilentlyContinue) 
{ 
   pandoc -Ss readme.txt -o readme.html
}

If you’d like to test the non-existence of a command in your path, for example to show an error message or download the executable (think NuGet):

if ((Get-Command "pandoc.exe" -ErrorAction SilentlyContinue) -eq $null) 
{ 
   Write-Host "Unable to find pandoc.exe in your PATH"
}

Try

(Get-Help gcm).description

in a PowerShell session to get information about Get-Command.