DOKK / manpages / debian 11 / nauty / nauty-catg.1.en
NAUTY-CATG(1) Nauty Manual NAUTY-CATG(1)

nauty-catg - concatenate files of graphs

catg [-xv] [infile]...

Copy files to stdout with all but the first header removed.
Don't write a header. In the absence of -x, a header is written if there is one in the first input file.
Summarize to stderr.
March 2021 nauty 2.7.1