add -nonbuf flag to help output

src/lammps.cpp

@@ -521,7 +521,8 @@ LAMMPS::LAMMPS(int narg, char **arg, MPI_Comm communicator) :
         error->one(FLERR,"Cannot open input script {}: {}", arg[inflag], utils::getsyserror());
       if (!helpflag)
         utils::logmesg(this,fmt::format("LAMMPS ({}{})\n",version,UPDATE_STRING));
-      // warn against using I/O redirection in parallel runs
+
+     // warn against using I/O redirection in parallel runs
       if ((inflag == 0) && (universe->nprocs > 1))
         error->warning(FLERR, "Using I/O redirection is unreliable with parallel runs. "
                        "Better use -in switch to read input file.");
@@ -1212,6 +1213,7 @@ void _noopt LAMMPS::help()
           "-mpicolor color             : which exe in a multi-exe mpirun cmd (-m)\n"
           "-cite                       : select citation reminder style (-c)\n"
           "-nocite                     : disable citation reminder (-nc)\n"
+          "-nonbuf                     : disable screen/logfile buffering (-nb)\n"
           "-package style ...          : invoke package command (-pk)\n"
           "-partition size1 size2 ...  : assign partition sizes (-p)\n"
           "-plog basename              : basename for partition logs (-pl)\n"