RunThrough["command", expr] executes an external command, giving the printed form of expr as input and taking the output, reading it as Mathematica input, and returning the ...
ScheduledTasks[] returns a list of ScheduledTaskObject expressions that represent current tasks.
ScriptBaselineShifts is an option for Style that specifies the minimum distance in x-heights to shift subscripts and superscripts.
Selectable is an option for displayed objects, cells, and notebooks that specifies whether their contents can be selected interactively using the front end.
SelectionAnimate[notebook] animates graphics in the current selection in a notebook. SelectionAnimate[notebook, t] animates graphics for t seconds.
SelectionEvaluate[notebook] replaces the current selection in a notebook with the result obtained by evaluating the contents of the selection in the kernel. ...
SessionTime[] gives the total number of seconds of real time that have elapsed since the beginning of your Mathematica session.
SetDirectory["dir"] sets the current working directory to dir. SetDirectory[] sets the current working directory to your "home" directory.
SetStreamPosition[stream, n] sets the current point in an open stream.
SetSystemOptions["name" -> value] resets the value for the internal system option with the specified name.