I have the following line in my .gitignore file:
var/www/docs/.backroom/billing_info/inv.pl
but when I type \'git status\' I am told the follow
That should only happen if inv.pl is already tracked (see gitignore man page).
inv.pl
Try (with git rm) a:
git rm --cached var/www/docs/.backroom/billing_info/inv.pl
If the file is already committed, see this SO answer.