xrectsel is a small program that tells you the geometry of a rectangular
screen region which you have selected by dragging the mouse / pointer.
When arguments are passed to
xrectsel, a limited set of
% format strings
are recognized and substituted. Look at the source to see what are supported.
libX11 to build.
To build and install from source,
./bootstrap # required if ./configure is not present ./configure --prefix /usr make make DESTDIR="$directory" install