Set or overwrite box information for frames.

box [x <xval>] [y <yval>] [z <zval>] [alpha <a>] [beta <b>] [gamma <g>] [nobox] [truncoct]

[x <xval>] [y <yval>] [z <zval>] Change box length(s) to specified value(s).
[alpha <a>] [beta <b>] [gamma <g>] Change box angle(s) to specified value(s).
[nobox] Remove any existing box information.
[truncoct] Set box angles to truncated octahedron.

Modify box information during trajectory processing. Note that this will permanently modify the box information for topology files during trajectory processing as well. It is possible to modify any number of the box parameters (e.g. only the Z length can be modified if desired while leaving all other parameters intact).