nauty-planarg man page
nauty-planarg — test graphs for planarity and find embeddings or obstructions
planarg [-v] [-nVq] [-p|-u] [infile [outfile]]
For each input, write to output if planar.
The output file has a header if and only if the input file does.
Write non-planar graphs instead of planar graphs
Write report on every input
Don't write anything, just count
Write in planar_code if planar (without -p, same format as input)
Follow each non-planar output with an obstruction in sparse6 format (implies -v, incompatible with -p)
Suppress checking of the result
Suppress auxiliary information
This program permits multiple edges and loops