Check if a File exists

[blueknight]

Hello so I am working on a command and I would like to make sure that the file exists and if not write a header (comma delimiated) to the file.

I know I have a variable that I am using that looks something like this.

Set Text [VAR-Systems-DIR] to '%userprofile%\Documents\EliteDangerous\BlueKnight\'
Set Text [VAR-Discovered-Systems] to 'Discovered-Systems.txt'
Set Text [VAR-Write-Discovered-Systems] to '{TXT:VAR-Systems-DIR}{TXT:VAR-Discovered-Systems}' (save value to profile)

While this works great in commands when I use this, I would just like to check if it exists first. I found a way to check the directory but not if the file exists in the docs.

[TheThingIs]

page 129 of the manual:

{STATE_FILEEXISTS:textVariable} - this will return “1” if the file indicated in the text variable exists, or “0” if it does not.