GFORTRAN_LIST_SEPARATOR—Separator for list output

This environment variable specifies the separator when writing list-directed output. It may contain any number of spaces and at most one comma. If you specify this on the command line, be sure to quote spaces, as in

$ GFORTRAN_LIST_SEPARATOR='  ,  ' ./a.out

when a.out is the compiled Fortran program that you want to run. Default is a single space.