$ dot -?
Usage: dot [-Vv?] [-(GNE)name=val] [-(KTlso)<val>] <dot files>
(additional options for neato) [-x] [-n<v>]
(additional options for fdp) [-L(gO)] [-L(nUCT)<val>]
(additional options for memtest) [-m<v>]
(additional options for config) [-cv]
-V - Print version and exit
-v - Enable verbose mode
-Gname=val - Set graph attribute 'name' to 'val'
-Nname=val - Set node attribute 'name' to 'val'
-Ename=val - Set edge attribute 'name' to 'val'
-Tv - Set output format to 'v'
-Kv - Set layout engine to 'v' (overrides default based on command name)
-lv - Use external library 'v'
-ofile - Write output to 'file'
-O - Automatically generate an output filename based on the input filename with a .'format' appended. (Causes all -ofile options to be ignored.)
-P - Internally generate a graph of the current plugins.
-q[l] - Set level of message suppression (=1)
-s[v] - Scale input by 'v' (=72)
-y - Invert y coordinate in output
-n[v] - No layout mode 'v' (=1)
-x - Reduce graph
-Lg - Don't use grid
-LO - Use old attractive force
-Ln<i> - Set number of iterations to i
-LU<i> - Set unscaled factor to i
-LC<v> - Set overlap expansion factor to v
-LT[*]<v> - Set temperature (temperature factor) to v
-m - Memory test (Observe no growth with top. Kill when done.)
-m[v] - Memory test - v iterations.
-c - Configure plugins (Writes $prefix/lib/graphviz/config
with available plugin information. Needs write privilege.)
-? - Print usage and exit