Исправление E, 20.12.19 13:00 (текущая версия) :
Backticks:
:<command> `<shell expression>` :tabedit `ls -t \| head -1`
https://stackoverflow.com/questions/31034570/how-can-i-use-the-output-of-an-external-command-as-an-argument-to-tabnew
Исходная версия E, 20.12.19 12:57:
:<command> `<shell expression>` :tabedit `ls -t | head -1`