nop

Check validity and pretty-print graphs in canonical format. Graphviz filters: acyclic, bcomps, comps, edgepaint, gvcolor, gvpack, mingle, nop, sccmap, tred, & unflatten. More information: https://www.graphviz.org/pdf/nop.1.pdf.

nop path/to/input1.gv path/to/input2.gv ... > path/to/output.gv

nop -p path/to/input1.gv path/to/input2.gv ...

nop -?