diff --git a/src/BOCS/fix_bocs.cpp b/src/BOCS/fix_bocs.cpp
index a3ec4b6b56..786ff216b0 100644
--- a/src/BOCS/fix_bocs.cpp
+++ b/src/BOCS/fix_bocs.cpp
@@ -233,9 +233,7 @@ FixBocs::FixBocs(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"mtk") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix bocs command");
-      if (strcmp(arg[iarg+1],"yes") == 0) mtk_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) mtk_flag = 0;
-      else error->all(FLERR,"Illegal fix bocs command");
+      mtk_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"tloop") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix bocs command");
diff --git a/src/EXTRA-COMPUTE/compute_ackland_atom.cpp b/src/EXTRA-COMPUTE/compute_ackland_atom.cpp
index 05fd374a10..dc55167dc5 100644
--- a/src/EXTRA-COMPUTE/compute_ackland_atom.cpp
+++ b/src/EXTRA-COMPUTE/compute_ackland_atom.cpp
@@ -18,20 +18,22 @@
    Updated algorithm by: Brian Barnes, brian.c.barnes11.civ@mail.mil
 ------------------------------------------------------------------------- */
 
-#include <cmath>
-#include <cstring>
 #include "compute_ackland_atom.h"
+
 #include "atom.h"
-#include "update.h"
+#include "comm.h"
+#include "error.h"
+#include "force.h"
+#include "memory.h"
 #include "modify.h"
-#include "neighbor.h"
 #include "neigh_list.h"
 #include "neigh_request.h"
-#include "force.h"
+#include "neighbor.h"
 #include "pair.h"
-#include "comm.h"
-#include "memory.h"
-#include "error.h"
+#include "update.h"
+
+#include <cmath>
+#include <cstring>
 
 using namespace LAMMPS_NS;
 
@@ -60,16 +62,10 @@ ComputeAcklandAtom::ComputeAcklandAtom(LAMMPS *lmp, int narg, char **arg) :
   int iarg = 3;
   while (narg > iarg) {
     if (strcmp("legacy",arg[iarg]) == 0) {
-      ++iarg;
-      if (iarg >= narg)
-        error->all(FLERR,"Invalid compute ackland/atom command");
-      if (strcmp("yes",arg[iarg]) == 0)
-        legacy = 1;
-      else if (strcmp("no",arg[iarg]) == 0)
-        legacy = 0;
-      else error->all(FLERR,"Invalid compute ackland/atom command");
+      if (iarg+2 > narg) error->all(FLERR,"Invalid compute ackland/atom command");
+      legacy = utils::logical(FLERR,arg[iarg+1],false,lmp);
+      iarg += 2;
     }
-    ++iarg;
   }
 }
 
diff --git a/src/atom.cpp b/src/atom.cpp
index 43d2578828..9fe115f5aa 100644
--- a/src/atom.cpp
+++ b/src/atom.cpp
@@ -822,17 +822,13 @@ void Atom::modify_params(int narg, char **arg)
     if (strcmp(arg[iarg],"id") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal atom_modify command");
       if (domain->box_exist)
-        error->all(FLERR,
-                   "Atom_modify id command after simulation box is defined");
-      if (strcmp(arg[iarg+1],"yes") == 0) tag_enable = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) tag_enable = 0;
-      else error->all(FLERR,"Illegal atom_modify command");
+        error->all(FLERR,"Atom_modify id command after simulation box is defined");
+      tag_enable = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"map") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal atom_modify command");
       if (domain->box_exist)
-        error->all(FLERR,
-                   "Atom_modify map command after simulation box is defined");
+        error->all(FLERR,"Atom_modify map command after simulation box is defined");
       if (strcmp(arg[iarg+1],"array") == 0) map_user = 1;
       else if (strcmp(arg[iarg+1],"hash") == 0) map_user = 2;
       else if (strcmp(arg[iarg+1],"yes") == 0) map_user = 3;
diff --git a/src/comm.cpp b/src/comm.cpp
index f79c48ace1..afe074cb5c 100644
--- a/src/comm.cpp
+++ b/src/comm.cpp
@@ -395,9 +395,7 @@ void Comm::modify_params(int narg, char **arg)
       iarg += 1;
     } else if (strcmp(arg[iarg],"vel") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal comm_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) ghost_velocity = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) ghost_velocity = 0;
-      else error->all(FLERR,"Illegal comm_modify command");
+      ghost_velocity = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal comm_modify command");
   }
diff --git a/src/compute.cpp b/src/compute.cpp
index 76a953484b..ba1d53e7c3 100644
--- a/src/compute.cpp
+++ b/src/compute.cpp
@@ -128,9 +128,7 @@ void Compute::modify_params(int narg, char **arg)
     } else if (strcmp(arg[iarg],"dynamic") == 0 ||
                strcmp(arg[iarg],"dynamic/dof") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal compute_modify command");
-      if (strcmp(arg[iarg+1],"no") == 0) dynamic_user = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) dynamic_user = 1;
-      else error->all(FLERR,"Illegal compute_modify command");
+      dynamic_user = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal compute_modify command");
   }
diff --git a/src/compute_centro_atom.cpp b/src/compute_centro_atom.cpp
index 5816bee17a..90f535613b 100644
--- a/src/compute_centro_atom.cpp
+++ b/src/compute_centro_atom.cpp
@@ -17,19 +17,21 @@
 ------------------------------------------------------------------------- */
 
 #include "compute_centro_atom.h"
-#include <cstring>
+
 #include "atom.h"
-#include "update.h"
-#include "modify.h"
-#include "neighbor.h"
-#include "neigh_list.h"
-#include "neigh_request.h"
-#include "force.h"
-#include "pair.h"
 #include "comm.h"
+#include "error.h"
+#include "force.h"
 #include "math_extra.h"
 #include "memory.h"
-#include "error.h"
+#include "modify.h"
+#include "neigh_list.h"
+#include "neigh_request.h"
+#include "neighbor.h"
+#include "pair.h"
+#include "update.h"
+
+#include <cstring>
 
 using namespace LAMMPS_NS;
 
@@ -55,11 +57,8 @@ ComputeCentroAtom::ComputeCentroAtom(LAMMPS *lmp, int narg, char **arg) :
   int iarg = 4;
   while (iarg < narg) {
     if (strcmp(arg[iarg],"axes") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute centro/atom command3");
-      if (strcmp(arg[iarg+1],"yes") == 0) axes_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) axes_flag = 0;
-      else error->all(FLERR,"Illegal compute centro/atom command2");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute centro/atom command3");
+      axes_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal compute centro/atom command1");
   }
diff --git a/src/compute_chunk_atom.cpp b/src/compute_chunk_atom.cpp
index 5d789f722a..fc4f17e53a 100644
--- a/src/compute_chunk_atom.cpp
+++ b/src/compute_chunk_atom.cpp
@@ -220,9 +220,7 @@ ComputeChunkAtom::ComputeChunkAtom(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"compress") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal compute chunk/atom command");
-      else if (strcmp(arg[iarg+1],"no") == 0) compress = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) compress = 1;
-      else error->all(FLERR,"Illegal compute chunk/atom command");
+      compress = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"discard") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal compute chunk/atom command");
@@ -255,9 +253,7 @@ ComputeChunkAtom::ComputeChunkAtom(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"pbc") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal compute chunk/atom command");
-      if (strcmp(arg[iarg+1],"no") == 0) pbcflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) pbcflag = 1;
-      else error->all(FLERR,"Illegal compute chunk/atom command");
+      pbcflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal compute chunk/atom command");
   }
diff --git a/src/compute_fragment_atom.cpp b/src/compute_fragment_atom.cpp
index b0a72080df..9ed57fef60 100644
--- a/src/compute_fragment_atom.cpp
+++ b/src/compute_fragment_atom.cpp
@@ -54,9 +54,7 @@ ComputeFragmentAtom::ComputeFragmentAtom(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"single") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal compute fragment/atom command");
-      if (strcmp(arg[iarg+1],"yes") == 0) singleflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) singleflag = 0;
-      else error->all(FLERR,"Illegal compute fragment/atom command");
+      singleflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal compute fragment/atom command");
   }
diff --git a/src/compute_group_group.cpp b/src/compute_group_group.cpp
index 161126b53a..db26a75880 100644
--- a/src/compute_group_group.cpp
+++ b/src/compute_group_group.cpp
@@ -19,21 +19,22 @@
 
 #include "compute_group_group.h"
 
-#include <cstring>
-#include <cmath>
 #include "atom.h"
-#include "update.h"
-#include "force.h"
-#include "pair.h"
-#include "neighbor.h"
-#include "neigh_request.h"
-#include "neigh_list.h"
-#include "group.h"
-#include "kspace.h"
-#include "error.h"
 #include "comm.h"
 #include "domain.h"
+#include "error.h"
+#include "force.h"
+#include "group.h"
+#include "kspace.h"
 #include "math_const.h"
+#include "neigh_list.h"
+#include "neigh_request.h"
+#include "neighbor.h"
+#include "pair.h"
+#include "update.h"
+
+#include <cstring>
+#include <cmath>
 
 using namespace LAMMPS_NS;
 using namespace MathConst;
@@ -69,29 +70,19 @@ ComputeGroupGroup::ComputeGroupGroup(LAMMPS *lmp, int narg, char **arg) :
   int iarg = 4;
   while (iarg < narg) {
     if (strcmp(arg[iarg],"pair") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute group/group command");
-      if (strcmp(arg[iarg+1],"yes") == 0) pairflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) pairflag = 0;
-      else error->all(FLERR,"Illegal compute group/group command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute group/group command");
+      pairflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"kspace") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute group/group command");
-      if (strcmp(arg[iarg+1],"yes") == 0) kspaceflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) kspaceflag = 0;
-      else error->all(FLERR,"Illegal compute group/group command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute group/group command");
+      kspaceflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"boundary") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute group/group command");
-      if (strcmp(arg[iarg+1],"yes") == 0) boundaryflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) boundaryflag  = 0;
-      else error->all(FLERR,"Illegal compute group/group command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute group/group command");
+      boundaryflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"molecule") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute group/group command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute group/group command");
       if (strcmp(arg[iarg+1],"off") == 0) molflag = OFF;
       else if (strcmp(arg[iarg+1],"inter") == 0) molflag = INTER;
       else if (strcmp(arg[iarg+1],"intra") == 0) molflag  = INTRA;
diff --git a/src/compute_msd.cpp b/src/compute_msd.cpp
index 209eec2810..7eee23a466 100644
--- a/src/compute_msd.cpp
+++ b/src/compute_msd.cpp
@@ -49,15 +49,11 @@ ComputeMSD::ComputeMSD(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"com") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal compute msd command");
-      if (strcmp(arg[iarg+1],"no") == 0) comflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) comflag = 1;
-      else error->all(FLERR,"Illegal compute msd command");
+      comflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"average") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal compute msd command");
-      if (strcmp(arg[iarg+1],"no") == 0) avflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) avflag = 1;
-      else error->all(FLERR,"Illegal compute msd command");
+      avflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal compute msd command");
   }
diff --git a/src/compute_orientorder_atom.cpp b/src/compute_orientorder_atom.cpp
index b77e68062f..d4291251b6 100644
--- a/src/compute_orientorder_atom.cpp
+++ b/src/compute_orientorder_atom.cpp
@@ -83,53 +83,41 @@ ComputeOrientOrderAtom::ComputeOrientOrderAtom(LAMMPS *lmp, int narg, char **arg
   int iarg = 3;
   while (iarg < narg) {
     if (strcmp(arg[iarg],"nnn") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute orientorder/atom command");
       if (strcmp(arg[iarg+1],"NULL") == 0) {
         nnn = 0;
       } else {
         nnn = utils::numeric(FLERR,arg[iarg+1],false,lmp);
-        if (nnn <= 0)
-          error->all(FLERR,"Illegal compute orientorder/atom command");
+        if (nnn <= 0) error->all(FLERR,"Illegal compute orientorder/atom command");
       }
       iarg += 2;
     } else if (strcmp(arg[iarg],"degrees") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute orientorder/atom command");
       nqlist = utils::numeric(FLERR,arg[iarg+1],false,lmp);
-      if (nqlist <= 0)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (nqlist <= 0) error->all(FLERR,"Illegal compute orientorder/atom command");
       memory->destroy(qlist);
       memory->create(qlist,nqlist,"orientorder/atom:qlist");
       iarg += 2;
-      if (iarg+nqlist > narg)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (iarg+nqlist > narg) error->all(FLERR,"Illegal compute orientorder/atom command");
       qmax = 0;
       for (int il = 0; il < nqlist; il++) {
         qlist[il] = utils::numeric(FLERR,arg[iarg+il],false,lmp);
-        if (qlist[il] < 0)
-          error->all(FLERR,"Illegal compute orientorder/atom command");
+        if (qlist[il] < 0) error->all(FLERR,"Illegal compute orientorder/atom command");
         if (qlist[il] > qmax) qmax = qlist[il];
       }
       iarg += nqlist;
     } else if (strcmp(arg[iarg],"wl") == 0) {
       if (iarg+2 > narg)
         error->all(FLERR,"Illegal compute orientorder/atom command");
-      if (strcmp(arg[iarg+1],"yes") == 0) wlflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) wlflag = 0;
-      else error->all(FLERR,"Illegal compute orientorder/atom command");
+      wlflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"wl/hat") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
-      if (strcmp(arg[iarg+1],"yes") == 0) wlhatflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) wlhatflag = 0;
-      else error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute orientorder/atom command");
+      wlhatflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"components") == 0) {
       qlcompflag = 1;
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute orientorder/atom command");
       qlcomp = utils::numeric(FLERR,arg[iarg+1],false,lmp);
       iqlcomp = -1;
       for (int il = 0; il < nqlist; il++)
@@ -137,23 +125,18 @@ ComputeOrientOrderAtom::ComputeOrientOrderAtom(LAMMPS *lmp, int narg, char **arg
           iqlcomp = il;
           break;
         }
-      if (iqlcomp == -1)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (iqlcomp == -1) error->all(FLERR,"Illegal compute orientorder/atom command");
       iarg += 2;
     } else if (strcmp(arg[iarg],"cutoff") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute orientorder/atom command");
       double cutoff = utils::numeric(FLERR,arg[iarg+1],false,lmp);
-      if (cutoff <= 0.0)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (cutoff <= 0.0) error->all(FLERR,"Illegal compute orientorder/atom command");
       cutsq = cutoff*cutoff;
       iarg += 2;
     } else if (strcmp(arg[iarg],"chunksize") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute orientorder/atom command");
       chunksize = utils::numeric(FLERR,arg[iarg+1],false,lmp);
-      if (chunksize <= 0)
-        error->all(FLERR,"Illegal compute orientorder/atom command");
+      if (chunksize <= 0) error->all(FLERR,"Illegal compute orientorder/atom command");
       iarg += 2;
     } else error->all(FLERR,"Illegal compute orientorder/atom command");
   }
diff --git a/src/compute_temp_chunk.cpp b/src/compute_temp_chunk.cpp
index 60014c7e21..8798835071 100644
--- a/src/compute_temp_chunk.cpp
+++ b/src/compute_temp_chunk.cpp
@@ -14,15 +14,16 @@
 
 #include "compute_temp_chunk.h"
 
-#include <cstring>
 #include "atom.h"
-#include "update.h"
-#include "force.h"
-#include "modify.h"
 #include "compute_chunk_atom.h"
 #include "domain.h"
-#include "memory.h"
 #include "error.h"
+#include "force.h"
+#include "memory.h"
+#include "modify.h"
+#include "update.h"
+
+#include <cstring>
 
 using namespace LAMMPS_NS;
 
@@ -76,26 +77,20 @@ ComputeTempChunk::ComputeTempChunk(LAMMPS *lmp, int narg, char **arg) :
 
   while (iarg < narg) {
     if (strcmp(arg[iarg],"com") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute temp/chunk command");
-      if (strcmp(arg[iarg+1],"yes") == 0) comflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) comflag = 0;
-      else error->all(FLERR,"Illegal compute temp/chunk command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute temp/chunk command");
+      comflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"bias") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute temp/chunk command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute temp/chunk command");
       biasflag = 1;
       id_bias = utils::strdup(arg[iarg+1]);
       iarg += 2;
     } else if (strcmp(arg[iarg],"adof") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute temp/chunk command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute temp/chunk command");
       adof = utils::numeric(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"cdof") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute temp/chunk command");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute temp/chunk command");
       cdof = utils::numeric(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal compute temp/chunk command");
diff --git a/src/create_atoms.cpp b/src/create_atoms.cpp
index cdcdc42a45..8baf6f88f7 100644
--- a/src/create_atoms.cpp
+++ b/src/create_atoms.cpp
@@ -151,9 +151,7 @@ void CreateAtoms::command(int narg, char **arg)
       iarg += 3;
     } else if (strcmp(arg[iarg],"remap") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal create_atoms command");
-      if (strcmp(arg[iarg+1],"yes") == 0) remapflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) remapflag = 0;
-      else error->all(FLERR,"Illegal create_atoms command");
+      remapflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"mol") == 0) {
       if (iarg+3 > narg) error->all(FLERR,"Illegal create_atoms command");
diff --git a/src/create_bonds.cpp b/src/create_bonds.cpp
index 99cfdfa958..ab3bba7041 100644
--- a/src/create_bonds.cpp
+++ b/src/create_bonds.cpp
@@ -125,9 +125,7 @@ void CreateBonds::command(int narg, char **arg)
   while (iarg < narg) {
     if (strcmp(arg[iarg],"special") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal create_bonds command");
-      if (strcmp(arg[iarg+1],"yes") == 0) specialflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) specialflag = 0;
-      else error->all(FLERR,"Illegal create_bonds command");
+      specialflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal create_bonds command");
   }
diff --git a/src/delete_atoms.cpp b/src/delete_atoms.cpp
index a9c25200d1..55b05e3d98 100644
--- a/src/delete_atoms.cpp
+++ b/src/delete_atoms.cpp
@@ -738,30 +738,21 @@ void DeleteAtoms::options(int narg, char **arg)
   while (iarg < narg) {
     if (strcmp(arg[iarg],"compress") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal delete_atoms command");
-      if (strcmp(arg[iarg+1],"yes") == 0) compress_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) compress_flag = 0;
-      else error->all(FLERR,"Illegal delete_atoms command");
+      compress_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"bond") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal delete_atoms command");
       if (atom->molecular == Atom::ATOMIC)
-        error->all(FLERR,"Cannot delete_atoms bond yes for "
-                   "non-molecular systems");
+        error->all(FLERR,"Cannot delete_atoms bond yes for non-molecular systems");
       if (atom->molecular == Atom::TEMPLATE)
-        error->all(FLERR,"Cannot use delete_atoms bond yes with "
-                   "atom_style template");
-      if (strcmp(arg[iarg+1],"yes") == 0) bond_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) bond_flag = 0;
-      else error->all(FLERR,"Illegal delete_atoms command");
+        error->all(FLERR,"Cannot use delete_atoms bond yes with atom_style template");
+      bond_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"mol") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal delete_atoms command");
       if (atom->molecule_flag == 0)
-        error->all(FLERR,"Delete_atoms mol yes requires "
-                   "atom attribute molecule");
-      if (strcmp(arg[iarg+1],"yes") == 0) mol_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) mol_flag = 0;
-      else error->all(FLERR,"Illegal delete_atoms command");
+        error->all(FLERR,"Delete_atoms mol yes requires atom attribute molecule");
+      mol_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal delete_atoms command");
   }
diff --git a/src/dump.cpp b/src/dump.cpp
index b42797833b..647fd3d38d 100644
--- a/src/dump.cpp
+++ b/src/dump.cpp
@@ -912,16 +912,12 @@ void Dump::modify_params(int narg, char **arg)
   while (iarg < narg) {
     if (strcmp(arg[iarg],"append") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) append_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) append_flag = 0;
-      else error->all(FLERR,"Illegal dump_modify command");
+      append_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg],"buffer") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) buffer_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) buffer_flag = 0;
-      else error->all(FLERR,"Illegal dump_modify command");
+      buffer_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       if (buffer_flag && buffer_allow == 0)
         error->all(FLERR,"Dump_modify buffer yes not allowed for this style");
       iarg += 2;
@@ -935,9 +931,7 @@ void Dump::modify_params(int narg, char **arg)
 
     } else if (strcmp(arg[iarg],"header") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) write_header_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) write_header_flag = 0;
-      else error->all(FLERR,"Illegal dump_modify command");
+      header_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg],"every") == 0) {
@@ -960,8 +954,7 @@ void Dump::modify_params(int narg, char **arg)
     } else if (strcmp(arg[iarg],"fileper") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
       if (!multiproc)
-        error->all(FLERR,"Cannot use dump_modify fileper "
-                   "without % in dump file name");
+        error->all(FLERR,"Cannot use dump_modify fileper without % in dump file name");
       int nper = utils::inumeric(FLERR,arg[iarg+1],false,lmp);
       if (nper <= 0) error->all(FLERR,"Illegal dump_modify command");
 
@@ -986,16 +979,12 @@ void Dump::modify_params(int narg, char **arg)
 
     } else if (strcmp(arg[iarg],"first") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) first_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) first_flag = 0;
-      else error->all(FLERR,"Illegal dump_modify command");
+      first_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg],"flush") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) flush_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) flush_flag = 0;
-      else error->all(FLERR,"Illegal dump_modify command");
+      flush_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg],"format") == 0) {
@@ -1032,8 +1021,7 @@ void Dump::modify_params(int narg, char **arg)
     } else if (strcmp(arg[iarg],"maxfiles") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
       if (!multifile)
-        error->all(FLERR,"Cannot use dump_modify maxfiles "
-                   "without * in dump file name");
+        error->all(FLERR,"Cannot use dump_modify maxfiles without * in dump file name");
       // wipe out existing storage
       if (maxfiles > 0) {
         for (int idx=0; idx < numfiles; ++idx)
@@ -1053,8 +1041,7 @@ void Dump::modify_params(int narg, char **arg)
     } else if (strcmp(arg[iarg],"nfile") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
       if (!multiproc)
-        error->all(FLERR,"Cannot use dump_modify nfile "
-                   "without % in dump file name");
+        error->all(FLERR,"Cannot use dump_modify nfile without % in dump file name");
       int nfile = utils::inumeric(FLERR,arg[iarg+1],false,lmp);
       if (nfile <= 0) error->all(FLERR,"Illegal dump_modify command");
       nfile = MIN(nfile,nprocs);
@@ -1090,9 +1077,7 @@ void Dump::modify_params(int narg, char **arg)
 
     } else if (strcmp(arg[iarg],"pbc") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) pbcflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) pbcflag = 0;
-      else error->all(FLERR,"Illegal dump_modify command");
+      pbcflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg],"sort") == 0) {
@@ -1117,16 +1102,12 @@ void Dump::modify_params(int narg, char **arg)
 
     } else if (strcmp(arg[iarg],"time") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) time_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) time_flag = 0;
-      else error->all(FLERR,"Illegal dump_modify command");
+      time_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg],"units") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) unit_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) unit_flag = 0;
-      else error->all(FLERR,"Illegal dump_modify command");
+      unit_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else {
diff --git a/src/dump_atom.cpp b/src/dump_atom.cpp
index 79aaa1ffcd..f3a03735a3 100644
--- a/src/dump_atom.cpp
+++ b/src/dump_atom.cpp
@@ -13,13 +13,15 @@
 ------------------------------------------------------------------------- */
 
 #include "dump_atom.h"
-#include <cstring>
-#include "domain.h"
+
 #include "atom.h"
-#include "memory.h"
+#include "domain.h"
 #include "error.h"
+#include "memory.h"
 #include "update.h"
 
+#include <cstring>
+
 using namespace LAMMPS_NS;
 
 #define ONELINE 256
@@ -114,15 +116,11 @@ int DumpAtom::modify_param(int narg, char **arg)
 {
   if (strcmp(arg[0],"scale") == 0) {
     if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
-    if (strcmp(arg[1],"yes") == 0) scale_flag = 1;
-    else if (strcmp(arg[1],"no") == 0) scale_flag = 0;
-    else error->all(FLERR,"Illegal dump_modify command");
+    scale_flag = utils::logical(FLERR,arg[1],false,lmp);
     return 2;
   } else if (strcmp(arg[0],"image") == 0) {
     if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
-    if (strcmp(arg[1],"yes") == 0) image_flag = 1;
-    else if (strcmp(arg[1],"no") == 0) image_flag = 0;
-    else error->all(FLERR,"Illegal dump_modify command");
+    image_flag = utils::logical(FLERR,arg[1],false,lmp);
     return 2;
   }
   return 0;
diff --git a/src/dump_image.cpp b/src/dump_image.cpp
index f6ca49851d..c073d152f8 100644
--- a/src/dump_image.cpp
+++ b/src/dump_image.cpp
@@ -47,7 +47,7 @@ using namespace MathConst;
 enum{NUMERIC,ATOM,TYPE,ELEMENT,ATTRIBUTE};
 enum{SPHERE,LINE,TRI};           // also in some Body and Fix child classes
 enum{STATIC,DYNAMIC};
-enum{NO,YES};
+enum{NO=0,YES=1};
 
 /* ---------------------------------------------------------------------- */
 
@@ -146,9 +146,7 @@ DumpImage::DumpImage(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"atom") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal dump image command");
-      if (strcmp(arg[iarg+1],"yes") == 0) atomflag = YES;
-      else if (strcmp(arg[iarg+1],"no") == 0) atomflag = NO;
-      else error->all(FLERR,"Illegal dump image command");
+      atomflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg],"adiam") == 0) {
@@ -290,18 +288,14 @@ DumpImage::DumpImage(LAMMPS *lmp, int narg, char **arg) :
 
     } else if (strcmp(arg[iarg],"box") == 0) {
       if (iarg+3 > narg) error->all(FLERR,"Illegal dump image command");
-      if (strcmp(arg[iarg+1],"yes") == 0) boxflag = YES;
-      else if (strcmp(arg[iarg+1],"no") == 0) boxflag = NO;
-      else error->all(FLERR,"Illegal dump image command");
+      boxflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       boxdiam = utils::numeric(FLERR,arg[iarg+2],false,lmp);
       if (boxdiam < 0.0) error->all(FLERR,"Illegal dump image command");
       iarg += 3;
 
     } else if (strcmp(arg[iarg],"axes") == 0) {
       if (iarg+3 > narg) error->all(FLERR,"Illegal dump image command");
-      if (strcmp(arg[iarg+1],"yes") == 0) axesflag = YES;
-      else if (strcmp(arg[iarg+1],"no") == 0) axesflag = NO;
-      else error->all(FLERR,"Illegal dump image command");
+      axesflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       axeslen = utils::numeric(FLERR,arg[iarg+2],false,lmp);
       axesdiam = utils::numeric(FLERR,arg[iarg+3],false,lmp);
       if (axeslen < 0.0 || axesdiam < 0.0)
@@ -310,9 +304,7 @@ DumpImage::DumpImage(LAMMPS *lmp, int narg, char **arg) :
 
     } else if (strcmp(arg[iarg],"subbox") == 0) {
       if (iarg+3 > narg) error->all(FLERR,"Illegal dump image command");
-      if (strcmp(arg[iarg+1],"yes") == 0) subboxflag = YES;
-      else if (strcmp(arg[iarg+1],"no") == 0) subboxflag = NO;
-      else error->all(FLERR,"Illegal dump image command");
+      subboxflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       subboxdiam = utils::numeric(FLERR,arg[iarg+2],false,lmp);
       if (subboxdiam < 0.0) error->all(FLERR,"Illegal dump image command");
       iarg += 3;
@@ -327,9 +319,7 @@ DumpImage::DumpImage(LAMMPS *lmp, int narg, char **arg) :
 
     } else if (strcmp(arg[iarg],"ssao") == 0) {
       if (iarg+4 > narg) error->all(FLERR,"Illegal dump image command");
-      if (strcmp(arg[iarg+1],"yes") == 0) image->ssao = YES;
-      else if (strcmp(arg[iarg+1],"no") == 0) image->ssao = NO;
-      else error->all(FLERR,"Illegal dump image command");
+      image->ssao = utils::logical(FLERR,arg[iarg+1],false,lmp);
       int seed = utils::inumeric(FLERR,arg[iarg+2],false,lmp);
       if (seed <= 0) error->all(FLERR,"Illegal dump image command");
       image->seed = seed;
diff --git a/src/fix.cpp b/src/fix.cpp
index 8f5b60535c..996cd9b7d5 100644
--- a/src/fix.cpp
+++ b/src/fix.cpp
@@ -137,27 +137,19 @@ void Fix::modify_params(int narg, char **arg)
   while (iarg < narg) {
     if (strcmp(arg[iarg],"dynamic/dof") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix_modify command");
-      if (strcmp(arg[iarg+1],"no") == 0) dynamic = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) dynamic = 1;
-      else error->all(FLERR,"Illegal fix_modify command");
+      dynamic = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"energy") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix_modify command");
-      if (strcmp(arg[iarg+1],"no") == 0) thermo_energy = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) {
-        if (energy_global_flag == 0 && energy_peratom_flag == 0)
+      thermo_energy = utils::logical(FLERR,arg[iarg+1],false,lmp);
+      if (thermo_energy && !energy_global_flag && !energy_peratom_flag)
           error->all(FLERR,"Illegal fix_modify command");
-        thermo_energy = 1;
-      } else error->all(FLERR,"Illegal fix_modify command");
       iarg += 2;
     } else if (strcmp(arg[iarg],"virial") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix_modify command");
-      if (strcmp(arg[iarg+1],"no") == 0) thermo_virial = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) {
-        if (virial_global_flag == 0 && virial_peratom_flag == 0)
-          error->all(FLERR,"Illegal fix_modify command");
-        thermo_virial = 1;
-      } else error->all(FLERR,"Illegal fix_modify command");
+      thermo_virial = utils::logical(FLERR,arg[iarg+1],false,lmp);
+      if (thermo_virial && !virial_global_flag && !virial_peratom_flag)
+        error->all(FLERR,"Illegal fix_modify command");
       iarg += 2;
     } else if (strcmp(arg[iarg],"respa") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix_modify command");
diff --git a/src/fix_adapt.cpp b/src/fix_adapt.cpp
index 358cf8045f..766dc9cd74 100644
--- a/src/fix_adapt.cpp
+++ b/src/fix_adapt.cpp
@@ -158,21 +158,15 @@ nadapt(0), id_fix_diam(nullptr), id_fix_chg(nullptr), adapt(nullptr)
   while (iarg < narg) {
     if (strcmp(arg[iarg],"reset") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix adapt command");
-      if (strcmp(arg[iarg+1],"no") == 0) resetflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) resetflag = 1;
-      else error->all(FLERR,"Illegal fix adapt command");
+      resetflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"scale") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix adapt command");
-      if (strcmp(arg[iarg+1],"no") == 0) scaleflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) scaleflag = 1;
-      else error->all(FLERR,"Illegal fix adapt command");
+      scaleflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"mass") == 0) {
       if (iarg+2 > narg)error->all(FLERR,"Illegal fix adapt command");
-      if (strcmp(arg[iarg+1],"no") == 0) massflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) massflag = 1;
-      else error->all(FLERR,"Illegal fix adapt command");
+      massflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix adapt command");
   }
diff --git a/src/fix_box_relax.cpp b/src/fix_box_relax.cpp
index e80a4db593..7988657339 100644
--- a/src/fix_box_relax.cpp
+++ b/src/fix_box_relax.cpp
@@ -196,21 +196,15 @@ FixBoxRelax::FixBoxRelax(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"scalexy") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix box/relax command");
-      if (strcmp(arg[iarg+1],"yes") == 0) scalexy = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) scalexy = 0;
-      else error->all(FLERR,"Illegal fix box/relax command");
+      scalexy = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"scalexz") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix box/relax command");
-      if (strcmp(arg[iarg+1],"yes") == 0) scalexz = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) scalexz = 0;
-      else error->all(FLERR,"Illegal fix box/relax command");
+      scalexz = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"scaleyz") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix box/relax command");
-      if (strcmp(arg[iarg+1],"yes") == 0) scaleyz = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) scaleyz = 0;
-      else error->all(FLERR,"Illegal fix box/relax command");
+      scaleyz = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"fixedpoint") == 0) {
       if (iarg+4 > narg) error->all(FLERR,"Illegal fix box/relax command");
diff --git a/src/fix_deform.cpp b/src/fix_deform.cpp
index 4d923ae7ff..71429ac0f8 100644
--- a/src/fix_deform.cpp
+++ b/src/fix_deform.cpp
@@ -1008,9 +1008,7 @@ void FixDeform::options(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"flip") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix deform command");
-      if (strcmp(arg[iarg+1],"yes") == 0) flipflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) flipflag = 0;
-      else error->all(FLERR,"Illegal fix deform command");
+      flipflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix deform command");
   }
diff --git a/src/fix_evaporate.cpp b/src/fix_evaporate.cpp
index ceb9f52818..531dcf9ffd 100644
--- a/src/fix_evaporate.cpp
+++ b/src/fix_evaporate.cpp
@@ -14,19 +14,20 @@
 
 #include "fix_evaporate.h"
 
-#include <cstring>
 #include "atom.h"
 #include "atom_vec.h"
-#include "molecule.h"
-#include "update.h"
-#include "domain.h"
-#include "region.h"
 #include "comm.h"
+#include "domain.h"
+#include "error.h"
 #include "force.h"
 #include "group.h"
-#include "random_park.h"
 #include "memory.h"
-#include "error.h"
+#include "molecule.h"
+#include "random_park.h"
+#include "region.h"
+#include "update.h"
+
+#include <cstring>
 
 using namespace LAMMPS_NS;
 using namespace FixConst;
@@ -69,9 +70,7 @@ FixEvaporate::FixEvaporate(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"molecule") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix evaporate command");
-      if (strcmp(arg[iarg+1],"no") == 0) molflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) molflag = 1;
-      else error->all(FLERR,"Illegal fix evaporate command");
+      molflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix evaporate command");
   }
diff --git a/src/fix_halt.cpp b/src/fix_halt.cpp
index 3e207baae7..263386e2b0 100644
--- a/src/fix_halt.cpp
+++ b/src/fix_halt.cpp
@@ -34,7 +34,7 @@ using namespace FixConst;
 enum{BONDMAX,TLIMIT,DISKFREE,VARIABLE};
 enum{LT,LE,GT,GE,EQ,NEQ,XOR};
 enum{HARD,SOFT,CONTINUE};
-enum{NOMSG,YESMSG};
+enum{NOMSG=0,YESMSG=1};
 
 /* ---------------------------------------------------------------------- */
 
@@ -102,9 +102,7 @@ FixHalt::FixHalt(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"message") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix halt command");
-      if (strcmp(arg[iarg+1],"no") == 0) msgflag = NOMSG;
-      else if (strcmp(arg[iarg+1],"yes") == 0) msgflag = YESMSG;
-      else error->all(FLERR,"Illegal fix halt command");
+      msgflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"path") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix halt command");
diff --git a/src/fix_langevin.cpp b/src/fix_langevin.cpp
index ef1cb4eeaf..6e770689dc 100644
--- a/src/fix_langevin.cpp
+++ b/src/fix_langevin.cpp
@@ -128,9 +128,7 @@ FixLangevin::FixLangevin(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"omega") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix langevin command");
-      if (strcmp(arg[iarg+1],"no") == 0) oflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) oflag = 1;
-      else error->all(FLERR,"Illegal fix langevin command");
+      oflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"scale") == 0) {
       if (iarg+3 > narg) error->all(FLERR,"Illegal fix langevin command");
@@ -142,15 +140,11 @@ FixLangevin::FixLangevin(LAMMPS *lmp, int narg, char **arg) :
       iarg += 3;
     } else if (strcmp(arg[iarg],"tally") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix langevin command");
-      if (strcmp(arg[iarg+1],"no") == 0) tallyflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) tallyflag = 1;
-      else error->all(FLERR,"Illegal fix langevin command");
+      tallyflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"zero") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix langevin command");
-      if (strcmp(arg[iarg+1],"no") == 0) zeroflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) zeroflag = 1;
-      else error->all(FLERR,"Illegal fix langevin command");
+      zeroflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix langevin command");
   }
diff --git a/src/fix_nh.cpp b/src/fix_nh.cpp
index c906000ec5..91be322d82 100644
--- a/src/fix_nh.cpp
+++ b/src/fix_nh.cpp
@@ -17,23 +17,25 @@
 ------------------------------------------------------------------------- */
 
 #include "fix_nh.h"
-#include <cstring>
-#include <cmath>
+
 #include "atom.h"
+#include "comm.h"
+#include "compute.h"
+#include "domain.h"
+#include "error.h"
+#include "fix_deform.h"
 #include "force.h"
 #include "group.h"
-#include "comm.h"
-#include "neighbor.h"
 #include "irregular.h"
-#include "modify.h"
-#include "fix_deform.h"
-#include "compute.h"
 #include "kspace.h"
-#include "update.h"
-#include "respa.h"
-#include "domain.h"
 #include "memory.h"
-#include "error.h"
+#include "modify.h"
+#include "neighbor.h"
+#include "respa.h"
+#include "update.h"
+
+#include <cmath>
+#include <cstring>
 
 using namespace LAMMPS_NS;
 using namespace FixConst;
@@ -297,9 +299,7 @@ FixNH::FixNH(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"mtk") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
-      if (strcmp(arg[iarg+1],"yes") == 0) mtk_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) mtk_flag = 0;
-      else error->all(FLERR,"Illegal fix nvt/npt/nph command");
+      mtk_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"tloop") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
@@ -318,27 +318,19 @@ FixNH::FixNH(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"scalexy") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
-      if (strcmp(arg[iarg+1],"yes") == 0) scalexy = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) scalexy = 0;
-      else error->all(FLERR,"Illegal fix nvt/npt/nph command");
+      scalexy = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"scalexz") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
-      if (strcmp(arg[iarg+1],"yes") == 0) scalexz = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) scalexz = 0;
-      else error->all(FLERR,"Illegal fix nvt/npt/nph command");
+      scalexz = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"scaleyz") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
-      if (strcmp(arg[iarg+1],"yes") == 0) scaleyz = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) scaleyz = 0;
-      else error->all(FLERR,"Illegal fix nvt/npt/nph command");
+      scaleyz = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"flip") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
-      if (strcmp(arg[iarg+1],"yes") == 0) flipflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) flipflag = 0;
-      else error->all(FLERR,"Illegal fix nvt/npt/nph command");
+      flipflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"update") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
diff --git a/src/fix_print.cpp b/src/fix_print.cpp
index fa1eba4842..df5b5f77ff 100644
--- a/src/fix_print.cpp
+++ b/src/fix_print.cpp
@@ -64,14 +64,12 @@ FixPrint::FixPrint(LAMMPS *lmp, int narg, char **arg) :
         else fp = fopen(arg[iarg+1],"a");
         if (fp == nullptr)
           error->one(FLERR,"Cannot open fix print file {}: {}",
-                                       arg[iarg+1], utils::getsyserror());
+                     arg[iarg+1], utils::getsyserror());
       }
       iarg += 2;
     } else if (strcmp(arg[iarg],"screen") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix print command");
-      if (strcmp(arg[iarg+1],"yes") == 0) screenflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) screenflag = 0;
-      else error->all(FLERR,"Illegal fix print command");
+      screenflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"title") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix print command");
diff --git a/src/fix_property_atom.cpp b/src/fix_property_atom.cpp
index 8fcb0f2af0..f90d83af4b 100644
--- a/src/fix_property_atom.cpp
+++ b/src/fix_property_atom.cpp
@@ -151,9 +151,7 @@ FixPropertyAtom::FixPropertyAtom(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"ghost") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix property/atom command");
-      if (strcmp(arg[iarg+1],"no") == 0) border = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) border = 1;
-      else error->all(FLERR,"Illegal fix property/atom command");
+      border = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix property/atom command");
   }
diff --git a/src/fix_store_state.cpp b/src/fix_store_state.cpp
index e4d1634a07..cd29e785ec 100644
--- a/src/fix_store_state.cpp
+++ b/src/fix_store_state.cpp
@@ -231,9 +231,7 @@ FixStoreState::FixStoreState(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"com") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix store/state command");
-      if (strcmp(arg[iarg+1],"no") == 0) comflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) comflag = 1;
-      else error->all(FLERR,"Illegal fix store/state command");
+      comflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix store/state command");
   }
@@ -246,16 +244,13 @@ FixStoreState::FixStoreState(LAMMPS *lmp, int narg, char **arg) :
       if (icompute < 0)
         error->all(FLERR,"Compute ID for fix store/state does not exist");
       if (modify->compute[icompute]->peratom_flag == 0)
-        error->all(FLERR,"Fix store/state compute "
-                   "does not calculate per-atom values");
+        error->all(FLERR,"Fix store/state compute does not calculate per-atom values");
       if (argindex[i] == 0 &&
           modify->compute[icompute]->size_peratom_cols != 0)
-        error->all(FLERR,"Fix store/state compute does not "
-                   "calculate a per-atom vector");
+        error->all(FLERR,"Fix store/state compute does not calculate a per-atom vector");
       if (argindex[i] && modify->compute[icompute]->size_peratom_cols == 0)
         error->all(FLERR,
-                   "Fix store/state compute does not "
-                   "calculate a per-atom array");
+                   "Fix store/state compute does not calculate a per-atom array");
       if (argindex[i] &&
           argindex[i] > modify->compute[icompute]->size_peratom_cols)
         error->all(FLERR,
diff --git a/src/fix_wall.cpp b/src/fix_wall.cpp
index bec669ff10..0c3623857e 100644
--- a/src/fix_wall.cpp
+++ b/src/fix_wall.cpp
@@ -128,15 +128,11 @@ FixWall::FixWall(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"fld") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix wall command");
-      if (strcmp(arg[iarg+1],"no") == 0) fldflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) fldflag = 1;
-      else error->all(FLERR,"Illegal fix wall command");
+      fldflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"pbc") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix wall command");
-      if (strcmp(arg[iarg+1],"yes") == 0) pbcflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) pbcflag = 0;
-      else error->all(FLERR,"Illegal fix wall command");
+      pbcflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix wall command");
   }
diff --git a/src/force.cpp b/src/force.cpp
index 62d9738206..6b7e9033ca 100644
--- a/src/force.cpp
+++ b/src/force.cpp
@@ -811,15 +811,11 @@ void Force::set_special(int narg, char **arg)
       iarg += 4;
     } else if (strcmp(arg[iarg],"angle") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal special_bonds command");
-      if (strcmp(arg[iarg+1],"no") == 0) special_angle = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) special_angle = 1;
-      else error->all(FLERR,"Illegal special_bonds command");
+      special_angle = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"dihedral") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal special_bonds command");
-      if (strcmp(arg[iarg+1],"no") == 0) special_dihedral = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) special_dihedral = 1;
-      else error->all(FLERR,"Illegal special_bonds command");
+      special_dihedral = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal special_bonds command");
   }
diff --git a/src/input.cpp b/src/input.cpp
index f67438d635..bfd0d56632 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -1068,19 +1068,14 @@ void Input::partition()
 {
   if (narg < 3) error->all(FLERR,"Illegal partition command");
 
-  int yesflag = 0;
-  if (strcmp(arg[0],"yes") == 0) yesflag = 1;
-  else if (strcmp(arg[0],"no") == 0) yesflag = 0;
-  else error->all(FLERR,"Illegal partition command");
-
   int ilo,ihi;
+  int yesflag = utils::logical(FLERR,arg[0],false,lmp);
   utils::bounds(FLERR,arg[1],1,universe->nworlds,ilo,ihi,error);
 
   // new command starts at the 3rd argument,
   // which must not be another partition command
 
-  if (strcmp(arg[2],"partition") == 0)
-    error->all(FLERR,"Illegal partition command");
+  if (strcmp(arg[2],"partition") == 0) error->all(FLERR,"Illegal partition command");
 
   char *cmd = strstr(line,arg[2]);
 
@@ -1123,21 +1118,16 @@ void Input::print()
         if (strcmp(arg[iarg],"file") == 0) fp = fopen(arg[iarg+1],"w");
         else fp = fopen(arg[iarg+1],"a");
         if (fp == nullptr)
-          error->one(FLERR,"Cannot open print file {}: {}",
-                                       arg[iarg+1], utils::getsyserror());
+          error->one(FLERR,"Cannot open print file {}: {}", arg[iarg+1], utils::getsyserror());
       }
       iarg += 2;
     } else if (strcmp(arg[iarg],"screen") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal print command");
-      if (strcmp(arg[iarg+1],"yes") == 0) screenflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) screenflag = 0;
-      else error->all(FLERR,"Illegal print command");
+      screenflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"universe") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal print command");
-      if (strcmp(arg[iarg+1],"yes") == 0) universeflag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) universeflag = 0;
-      else error->all(FLERR,"Illegal print command");
+      universeflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal print command");
   }
diff --git a/src/kspace.cpp b/src/kspace.cpp
index a18a9ca702..fb995fca8a 100644
--- a/src/kspace.cpp
+++ b/src/kspace.cpp
@@ -480,8 +480,7 @@ void KSpace::modify_params(int narg, char **arg)
       if (nx_pppm_6 == 0 && ny_pppm_6 == 0 && nz_pppm_6 == 0)
         gridflag_6 = 0;
       else if (nx_pppm_6 <= 0 || ny_pppm_6 <= 0 || nz_pppm_6 == 0)
-        error->all(FLERR,"Kspace_modify mesh/disp parameters must be all "
-                   "zero or all positive");
+        error->all(FLERR,"Kspace_modify mesh/disp parameters must be all zero or all positive");
       else gridflag_6 = 1;
       iarg += 4;
     } else if (strcmp(arg[iarg],"order") == 0) {
@@ -499,9 +498,7 @@ void KSpace::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"overlap") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) overlap_allowed = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) overlap_allowed = 0;
-      else error->all(FLERR,"Illegal kspace_modify command");
+      overlap_allowed = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"force") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
@@ -535,21 +532,15 @@ void KSpace::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"compute") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) compute_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) compute_flag = 0;
-      else error->all(FLERR,"Illegal kspace_modify command");
+      compute_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"fftbench") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) fftbench = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) fftbench = 0;
-      else error->all(FLERR,"Illegal kspace_modify command");
+      fftbench = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"collective") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) collective_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) collective_flag = 0;
-      else error->all(FLERR,"Illegal kspace_modify command");
+      collective_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"diff") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
@@ -559,9 +550,7 @@ void KSpace::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"cutoff/adjust") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) adjust_cutoff_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) adjust_cutoff_flag = 0;
-      else error->all(FLERR,"Illegal kspace_modify command");
+      adjust_cutoff_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"kmax/ewald") == 0) {
       if (iarg+4 > narg) error->all(FLERR,"Illegal kspace_modify command");
@@ -598,15 +587,11 @@ void KSpace::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"pressure/scalar") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) scalar_pressure_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) scalar_pressure_flag = 0;
-      else error->all(FLERR,"Illegal kspace_modify command");
+      scalar_pressure_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"disp/auto") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) auto_disp_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) auto_disp_flag = 0;
-      else error->all(FLERR,"Illegal kspace_modify command");
+      auto_disp_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else {
       int n = modify_param(narg-iarg,&arg[iarg]);
diff --git a/src/min.cpp b/src/min.cpp
index ab8b1a5235..4780cf31eb 100644
--- a/src/min.cpp
+++ b/src/min.cpp
@@ -705,15 +705,11 @@ void Min::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"halfstepback") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal min_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) halfstepback_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) halfstepback_flag = 0;
-      else error->all(FLERR,"Illegal min_modify command");
+      halfstepback_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"initialdelay") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal min_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) delaystep_start_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) delaystep_start_flag = 0;
-      else error->all(FLERR,"Illegal min_modify command");
+      delaystep_start_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"vdfmax") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal min_modify command");
diff --git a/src/neighbor.cpp b/src/neighbor.cpp
index d58823063c..c88885fc54 100644
--- a/src/neighbor.cpp
+++ b/src/neighbor.cpp
@@ -2404,15 +2404,11 @@ void Neighbor::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"check") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal neigh_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) dist_check = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) dist_check = 0;
-      else error->all(FLERR,"Illegal neigh_modify command");
+      dist_check = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"once") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal neigh_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) build_once = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) build_once = 0;
-      else error->all(FLERR,"Illegal neigh_modify command");
+      build_once = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"page") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal neigh_modify command");
@@ -2432,9 +2428,7 @@ void Neighbor::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"cluster") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal neigh_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) cluster_check = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) cluster_check = 0;
-      else error->all(FLERR,"Illegal neigh_modify command");
+      cluster_check = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg],"include") == 0) {
diff --git a/src/pair.cpp b/src/pair.cpp
index 38a21481cd..6805166150 100644
--- a/src/pair.cpp
+++ b/src/pair.cpp
@@ -167,9 +167,7 @@ void Pair::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"shift") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal pair_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) offset_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) offset_flag = 0;
-      else error->all(FLERR,"Illegal pair_modify command");
+      offset_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"table") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal pair_modify command");
@@ -193,15 +191,11 @@ void Pair::modify_params(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"tail") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal pair_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) tail_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) tail_flag = 0;
-      else error->all(FLERR,"Illegal pair_modify command");
+      tail_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"compute") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal pair_modify command");
-      if (strcmp(arg[iarg+1],"yes") == 0) compute_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) compute_flag = 0;
-      else error->all(FLERR,"Illegal pair_modify command");
+      compute_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"nofdotr") == 0) {
       no_virial_fdotr_compute = 1;
diff --git a/src/pair_hybrid.cpp b/src/pair_hybrid.cpp
index 67e0a70249..d1b5e5bd2e 100644
--- a/src/pair_hybrid.cpp
+++ b/src/pair_hybrid.cpp
@@ -918,8 +918,7 @@ void PairHybrid::modify_params(int narg, char **arg)
 again:
 
     if (iarg < narg && strcmp(arg[iarg],"special") == 0) {
-      if (narg < iarg+5)
-        error->all(FLERR,"Illegal pair_modify special command");
+      if (narg < iarg+5) error->all(FLERR,"Illegal pair_modify special command");
       modify_special(m,narg-iarg,&arg[iarg+1]);
       iarg += 5;
       goto again;
@@ -929,13 +928,8 @@ again:
     // set flag to register TALLY computes accordingly
 
     if (iarg < narg && strcmp(arg[iarg],"compute/tally") == 0) {
-      if (narg < iarg+2)
-        error->all(FLERR,"Illegal pair_modify compute/tally command");
-      if (strcmp(arg[iarg+1],"yes") == 0) {
-        compute_tally[m] = 1;
-      } else if (strcmp(arg[iarg+1],"no") == 0) {
-        compute_tally[m] = 0;
-      } else error->all(FLERR,"Illegal pair_modify compute/tally command");
+      if (narg < iarg+2) error->all(FLERR,"Illegal pair_modify compute/tally command");
+      compute_tally[m] = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
       goto again;
     }
diff --git a/unittest/commands/test_simple_commands.cpp b/unittest/commands/test_simple_commands.cpp
index 8b57c26af1..b2e5ac1838 100644
--- a/unittest/commands/test_simple_commands.cpp
+++ b/unittest/commands/test_simple_commands.cpp
@@ -160,7 +160,8 @@ TEST_F(SimpleCommandsTest, Partition)
     BEGIN_HIDE_OUTPUT();
     command("echo none");
     END_HIDE_OUTPUT();
-    TEST_FAILURE(".*ERROR: Illegal partition command .*", command("partition xxx 1 echo none"););
+    TEST_FAILURE(".*ERROR: Expected boolean parameter instead of 'xxx'.*",
+                 command("partition xxx 1 echo none"););
     TEST_FAILURE(".*ERROR: Numeric index 2 is out of bounds.*",
                  command("partition yes 2 echo none"););
 
diff --git a/unittest/formats/test_dump_atom.cpp b/unittest/formats/test_dump_atom.cpp
index b11dd4e800..8a3dab44a4 100644
--- a/unittest/formats/test_dump_atom.cpp
+++ b/unittest/formats/test_dump_atom.cpp
@@ -120,7 +120,7 @@ TEST_F(DumpAtomTest, format_line_run0)
 TEST_F(DumpAtomTest, no_scale_run0)
 {
     auto dump_file = "dump_no_scale_run0.melt";
-    generate_dump(dump_file, "scale no", 0);
+    generate_dump(dump_file, "scale off", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -135,7 +135,7 @@ TEST_F(DumpAtomTest, no_scale_run0)
 TEST_F(DumpAtomTest, no_buffer_no_scale_run0)
 {
     auto dump_file = "dump_no_buffer_no_scale_run0.melt";
-    generate_dump(dump_file, "buffer no scale no", 0);
+    generate_dump(dump_file, "buffer false scale false", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -150,7 +150,7 @@ TEST_F(DumpAtomTest, no_buffer_no_scale_run0)
 TEST_F(DumpAtomTest, no_buffer_with_scale_run0)
 {
     auto dump_file = "dump_no_buffer_with_scale_run0.melt";
-    generate_dump(dump_file, "buffer no scale yes", 0);
+    generate_dump(dump_file, "buffer 0 scale 1", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -165,7 +165,7 @@ TEST_F(DumpAtomTest, no_buffer_with_scale_run0)
 TEST_F(DumpAtomTest, with_image_run0)
 {
     auto dump_file = "dump_with_image_run0.melt";
-    generate_dump(dump_file, "scale no image yes", 0);
+    generate_dump(dump_file, "scale no image on", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -178,7 +178,7 @@ TEST_F(DumpAtomTest, with_image_run0)
 TEST_F(DumpAtomTest, with_units_run0)
 {
     auto dump_file = "dump_with_units_run0.melt";
-    generate_dump(dump_file, "scale no units yes", 0);
+    generate_dump(dump_file, "scale false units 1", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -193,7 +193,7 @@ TEST_F(DumpAtomTest, with_units_run0)
 TEST_F(DumpAtomTest, with_time_run0)
 {
     auto dump_file = "dump_with_time_run0.melt";
-    generate_dump(dump_file, "scale no time yes", 0);
+    generate_dump(dump_file, "scale off time true", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -207,7 +207,7 @@ TEST_F(DumpAtomTest, with_time_run0)
 TEST_F(DumpAtomTest, with_units_run1)
 {
     auto dump_file = "dump_with_units_run1.melt";
-    generate_dump(dump_file, "scale no units yes", 1);
+    generate_dump(dump_file, "scale 0 units on", 1);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -222,7 +222,7 @@ TEST_F(DumpAtomTest, with_units_run1)
 TEST_F(DumpAtomTest, no_buffer_with_scale_and_image_run0)
 {
     auto dump_file = "dump_no_buffer_with_scale_and_image_run0.melt";
-    generate_dump(dump_file, "buffer no scale yes image yes", 0);
+    generate_dump(dump_file, "buffer 0 scale 1 image true", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -253,7 +253,7 @@ TEST_F(DumpAtomTest, triclinic_with_units_run0)
 {
     auto dump_file = "dump_triclinic_with_units_run0.melt";
     enable_triclinic();
-    generate_dump(dump_file, "units yes", 0);
+    generate_dump(dump_file, "units on", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -271,7 +271,7 @@ TEST_F(DumpAtomTest, triclinic_with_time_run0)
 {
     auto dump_file = "dump_triclinic_with_time_run0.melt";
     enable_triclinic();
-    generate_dump(dump_file, "time yes", 0);
+    generate_dump(dump_file, "time on", 0);
 
     ASSERT_FILE_EXISTS(dump_file);
     auto lines = read_lines(dump_file);
@@ -548,7 +548,8 @@ TEST_F(DumpAtomTest, dump_modify_scale_invalid)
     command("dump id all atom 1 dump.txt");
     END_HIDE_OUTPUT();
 
-    TEST_FAILURE(".*Illegal dump_modify command.*", command("dump_modify id scale true"););
+    TEST_FAILURE(".*Expected boolean parameter instead of 'xxx'.*",
+                 command("dump_modify id scale xxx"););
 }
 
 TEST_F(DumpAtomTest, dump_modify_image_invalid)
@@ -557,7 +558,8 @@ TEST_F(DumpAtomTest, dump_modify_image_invalid)
     command("dump id all atom 1 dump.txt");
     END_HIDE_OUTPUT();
 
-    TEST_FAILURE(".*Illegal dump_modify command.*", command("dump_modify id image true"););
+    TEST_FAILURE(".*Expected boolean parameter instead of 'xxx'.*",
+                 command("dump_modify id image xxx"););
 }
 
 TEST_F(DumpAtomTest, dump_modify_invalid)