diff --git a/src/COLVARS/fix_colvars.cpp b/src/COLVARS/fix_colvars.cpp
index 5ee77768c6..32211f7689 100644
--- a/src/COLVARS/fix_colvars.cpp
+++ b/src/COLVARS/fix_colvars.cpp
@@ -312,32 +312,26 @@ FixColvars::FixColvars(LAMMPS *lmp, int narg, char **arg) :
   tmp_name = nullptr;
 
   /* parse optional arguments */
-  int argsdone = 4;
-  while (argsdone < narg) {
+  int iarg = 4;
+  while (iarg < narg) {
     // we have keyword/value pairs. check if value is missing
-    if (argsdone+1 == narg)
+    if (iarg+1 == narg)
       error->all(FLERR,"Missing argument to keyword");
 
-    if (0 == strcmp(arg[argsdone], "input")) {
-      inp_name = strdup(arg[argsdone+1]);
-    } else if (0 == strcmp(arg[argsdone], "output")) {
-      out_name = strdup(arg[argsdone+1]);
-    } else if (0 == strcmp(arg[argsdone], "seed")) {
-      rng_seed = utils::inumeric(FLERR,arg[argsdone+1],false,lmp);
-    } else if (0 == strcmp(arg[argsdone], "unwrap")) {
-      if (0 == strcmp(arg[argsdone+1], "yes")) {
-        unwrap_flag = 1;
-      } else if (0 == strcmp(arg[argsdone+1], "no")) {
-        unwrap_flag = 0;
-      } else {
-        error->all(FLERR,"Incorrect fix colvars unwrap flag");
-      }
-    } else if (0 == strcmp(arg[argsdone], "tstat")) {
-      tmp_name = strdup(arg[argsdone+1]);
+    if (0 == strcmp(arg[iarg], "input")) {
+      inp_name = strdup(arg[iarg+1]);
+    } else if (0 == strcmp(arg[iarg], "output")) {
+      out_name = strdup(arg[iarg+1]);
+    } else if (0 == strcmp(arg[iarg], "seed")) {
+      rng_seed = utils::inumeric(FLERR,arg[iarg+1],false,lmp);
+    } else if (0 == strcmp(arg[iarg], "unwrap")) {
+      unwrap_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
+    } else if (0 == strcmp(arg[iarg], "tstat")) {
+      tmp_name = strdup(arg[iarg+1]);
     } else {
       error->all(FLERR,"Unknown fix colvars parameter");
     }
-    ++argsdone; ++argsdone;
+    ++iarg; ++iarg;
   }
 
   if (!out_name) out_name = strdup("out");
diff --git a/src/COMPRESS/dump_atom_zstd.cpp b/src/COMPRESS/dump_atom_zstd.cpp
index aa9d14b324..a23ea2025b 100644
--- a/src/COMPRESS/dump_atom_zstd.cpp
+++ b/src/COMPRESS/dump_atom_zstd.cpp
@@ -188,17 +188,11 @@ int DumpAtomZstd::modify_param(int narg, char **arg)
     try {
       if (strcmp(arg[0], "checksum") == 0) {
         if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
-        if (strcmp(arg[1], "yes") == 0)
-          writer.setChecksum(true);
-        else if (strcmp(arg[1], "no") == 0)
-          writer.setChecksum(false);
-        else
-          error->all(FLERR, "Illegal dump_modify command");
+        writer.setChecksum(utils::logical(FLERR, arg[1], false, lmp) == 1);
         return 2;
       } else if (strcmp(arg[0], "compression_level") == 0) {
         if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
-        int compression_level = utils::inumeric(FLERR, arg[1], false, lmp);
-        writer.setCompressionLevel(compression_level);
+        writer.setCompressionLevel(utils::inumeric(FLERR, arg[1], false, lmp));
         return 2;
       }
     } catch (FileWriterException &e) {
diff --git a/src/COMPRESS/dump_cfg_zstd.cpp b/src/COMPRESS/dump_cfg_zstd.cpp
index 15ea1e540c..73ee3e7e11 100644
--- a/src/COMPRESS/dump_cfg_zstd.cpp
+++ b/src/COMPRESS/dump_cfg_zstd.cpp
@@ -233,17 +233,11 @@ int DumpCFGZstd::modify_param(int narg, char **arg)
     try {
       if (strcmp(arg[0], "checksum") == 0) {
         if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
-        if (strcmp(arg[1], "yes") == 0)
-          writer.setChecksum(true);
-        else if (strcmp(arg[1], "no") == 0)
-          writer.setChecksum(false);
-        else
-          error->all(FLERR, "Illegal dump_modify command");
+        writer.setChecksum(utils::logical(FLERR, arg[1], false, lmp) == 1);
         return 2;
       } else if (strcmp(arg[0], "compression_level") == 0) {
         if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
-        int compression_level = utils::inumeric(FLERR, arg[1], false, lmp);
-        writer.setCompressionLevel(compression_level);
+        writer.setCompressionLevel(utils::inumeric(FLERR, arg[1], false, lmp));
         return 2;
       }
     } catch (FileWriterException &e) {
diff --git a/src/COMPRESS/dump_custom_zstd.cpp b/src/COMPRESS/dump_custom_zstd.cpp
index 3824709d5e..8b7d153fc4 100644
--- a/src/COMPRESS/dump_custom_zstd.cpp
+++ b/src/COMPRESS/dump_custom_zstd.cpp
@@ -203,16 +203,13 @@ int DumpCustomZstd::modify_param(int narg, char **arg)
   int consumed = DumpCustom::modify_param(narg, arg);
   if (consumed == 0) {
     try {
-      if (strcmp(arg[0],"checksum") == 0) {
-        if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
-        if (strcmp(arg[1],"yes") == 0) writer.setChecksum(true);
-        else if (strcmp(arg[1],"no") == 0) writer.setChecksum(false);
-        else error->all(FLERR,"Illegal dump_modify command");
+      if (strcmp(arg[0], "checksum") == 0) {
+        if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
+        writer.setChecksum(utils::logical(FLERR, arg[1], false, lmp) == 1);
         return 2;
-      } else if (strcmp(arg[0],"compression_level") == 0) {
-        if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
-        int compression_level = utils::inumeric(FLERR, arg[1], false, lmp);
-        writer.setCompressionLevel(compression_level);
+      } else if (strcmp(arg[0], "compression_level") == 0) {
+        if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
+        writer.setCompressionLevel(utils::inumeric(FLERR, arg[1], false, lmp));
         return 2;
       }
     } catch (FileWriterException &e) {
diff --git a/src/COMPRESS/dump_local_zstd.cpp b/src/COMPRESS/dump_local_zstd.cpp
index cf233aff19..91fb36bb6e 100644
--- a/src/COMPRESS/dump_local_zstd.cpp
+++ b/src/COMPRESS/dump_local_zstd.cpp
@@ -190,17 +190,11 @@ int DumpLocalZstd::modify_param(int narg, char **arg)
     try {
       if (strcmp(arg[0], "checksum") == 0) {
         if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
-        if (strcmp(arg[1], "yes") == 0)
-          writer.setChecksum(true);
-        else if (strcmp(arg[1], "no") == 0)
-          writer.setChecksum(false);
-        else
-          error->all(FLERR, "Illegal dump_modify command");
+        writer.setChecksum(utils::logical(FLERR, arg[1], false, lmp) == 1);
         return 2;
       } else if (strcmp(arg[0], "compression_level") == 0) {
         if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
-        int compression_level = utils::inumeric(FLERR, arg[1], false, lmp);
-        writer.setCompressionLevel(compression_level);
+        writer.setCompressionLevel(utils::inumeric(FLERR, arg[1], false, lmp));
         return 2;
       }
     } catch (FileWriterException &e) {
diff --git a/src/COMPRESS/dump_xyz_zstd.cpp b/src/COMPRESS/dump_xyz_zstd.cpp
index d5c79d181b..534bc0ee56 100644
--- a/src/COMPRESS/dump_xyz_zstd.cpp
+++ b/src/COMPRESS/dump_xyz_zstd.cpp
@@ -156,17 +156,11 @@ int DumpXYZZstd::modify_param(int narg, char **arg)
     try {
       if (strcmp(arg[0], "checksum") == 0) {
         if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
-        if (strcmp(arg[1], "yes") == 0)
-          writer.setChecksum(true);
-        else if (strcmp(arg[1], "no") == 0)
-          writer.setChecksum(false);
-        else
-          error->all(FLERR, "Illegal dump_modify command");
+        writer.setChecksum(utils::logical(FLERR, arg[1], false, lmp) == 1);
         return 2;
       } else if (strcmp(arg[0], "compression_level") == 0) {
         if (narg < 2) error->all(FLERR, "Illegal dump_modify command");
-        int compression_level = utils::inumeric(FLERR, arg[1], false, lmp);
-        writer.setCompressionLevel(compression_level);
+        writer.setCompressionLevel(utils::inumeric(FLERR, arg[1], false, lmp));
         return 2;
       }
     } catch (FileWriterException &e) {
diff --git a/src/DIELECTRIC/fix_polarize_bem_gmres.cpp b/src/DIELECTRIC/fix_polarize_bem_gmres.cpp
index 538ce15575..f5f119f686 100644
--- a/src/DIELECTRIC/fix_polarize_bem_gmres.cpp
+++ b/src/DIELECTRIC/fix_polarize_bem_gmres.cpp
@@ -796,12 +796,7 @@ int FixPolarizeBEMGMRES::modify_param(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg], "kspace") == 0) {
       if (iarg + 2 > narg) error->all(FLERR, "Illegal fix_modify 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 fix_modify command for fix polarize");
+      kspaceflag = utils::logical(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "dielectrics") == 0) {
       if (iarg + 6 > narg) error->all(FLERR, "Illegal fix_modify command");
diff --git a/src/DIELECTRIC/fix_polarize_bem_icc.cpp b/src/DIELECTRIC/fix_polarize_bem_icc.cpp
index 4c137878a2..35171c0a19 100644
--- a/src/DIELECTRIC/fix_polarize_bem_icc.cpp
+++ b/src/DIELECTRIC/fix_polarize_bem_icc.cpp
@@ -355,12 +355,7 @@ int FixPolarizeBEMICC::modify_param(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg], "kspace") == 0) {
       if (iarg + 2 > narg) error->all(FLERR, "Illegal fix_modify 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 fix_modify command for fix polarize");
+      kspaceflag = utils::logical(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "dielectrics") == 0) {
       if (iarg + 6 > narg) error->all(FLERR, "Illegal fix_modify command");
diff --git a/src/DIELECTRIC/fix_polarize_functional.cpp b/src/DIELECTRIC/fix_polarize_functional.cpp
index 2d67bca0a7..2e43d40ba0 100644
--- a/src/DIELECTRIC/fix_polarize_functional.cpp
+++ b/src/DIELECTRIC/fix_polarize_functional.cpp
@@ -478,12 +478,7 @@ int FixPolarizeFunctional::modify_param(int narg, char **arg)
   while (iarg < narg) {
     if (strcmp(arg[iarg], "kspace") == 0) {
       if (iarg + 2 > narg) error->all(FLERR, "Illegal fix_modify 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 fix_modify command for fix polarize/functional");
+      kspaceflag = utils::logical(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "dielectrics") == 0) {
       if (iarg + 6 > narg) error->all(FLERR, "Illegal fix_modify command");
diff --git a/src/DRUDE/fix_langevin_drude.cpp b/src/DRUDE/fix_langevin_drude.cpp
index 205b36ce51..dea2f9ce62 100644
--- a/src/DRUDE/fix_langevin_drude.cpp
+++ b/src/DRUDE/fix_langevin_drude.cpp
@@ -91,9 +91,7 @@ FixLangevinDrude::FixLangevinDrude(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"zero") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix langevin/drude command");
-      if (strcmp(arg[iarg+1],"no") == 0) zero = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) zero = 1;
-      else error->all(FLERR,"Illegal fix langevin/drude command");
+      zero = utils::logical(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix langevin/drude command");
   }
diff --git a/src/DRUDE/fix_tgnh_drude.cpp b/src/DRUDE/fix_tgnh_drude.cpp
index fe8cf448f0..eb8922d4cc 100644
--- a/src/DRUDE/fix_tgnh_drude.cpp
+++ b/src/DRUDE/fix_tgnh_drude.cpp
@@ -256,9 +256,7 @@ FixTGNHDrude::FixTGNHDrude(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");
@@ -277,27 +275,19 @@ FixTGNHDrude::FixTGNHDrude(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],"fixedpoint") == 0) {
       if (iarg+4 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
diff --git a/src/EXTRA-COMPUTE/compute_entropy_atom.cpp b/src/EXTRA-COMPUTE/compute_entropy_atom.cpp
index d0866c946c..ac53bf1e7f 100644
--- a/src/EXTRA-COMPUTE/compute_entropy_atom.cpp
+++ b/src/EXTRA-COMPUTE/compute_entropy_atom.cpp
@@ -17,21 +17,23 @@
 ------------------------------------------------------------------------- */
 
 #include "compute_entropy_atom.h"
-#include <cmath>
-#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 "domain.h"
+#include "error.h"
+#include "force.h"
 #include "math_const.h"
 #include "memory.h"
-#include "error.h"
-#include "domain.h"
+#include "modify.h"
+#include "neigh_list.h"
+#include "neigh_request.h"
+#include "neighbor.h"
+#include "pair.h"
+#include "update.h"
+
+#include <cmath>
+#include <cstring>
 
 using namespace LAMMPS_NS;
 using namespace MathConst;
@@ -44,8 +46,7 @@ ComputeEntropyAtom(LAMMPS *lmp, int narg, char **arg) :
   pair_entropy(nullptr), pair_entropy_avg(nullptr)
 {
   if (narg < 5 || narg > 10)
-    error->all(FLERR,"Illegal compute entropy/atom command; wrong number"
-               " of arguments");
+    error->all(FLERR,"Illegal compute entropy/atom command; wrong number of arguments");
 
   // Arguments are: sigma cutoff avg yes/no cutoff2 local yes/no
   //   sigma is the gaussian width
@@ -57,11 +58,9 @@ ComputeEntropyAtom(LAMMPS *lmp, int narg, char **arg) :
   //     the g(r)
 
   sigma = utils::numeric(FLERR,arg[3],false,lmp);
-  if (sigma <= 0.0) error->all(FLERR,"Illegal compute entropy/atom"
-                              " command; sigma must be positive");
+  if (sigma <= 0.0) error->all(FLERR,"Illegal compute entropy/atom command; sigma must be positive");
   cutoff = utils::numeric(FLERR,arg[4],false,lmp);
-  if (cutoff <= 0.0) error->all(FLERR,"Illegal compute entropy/atom"
-                               " command; cutoff must be positive");
+  if (cutoff <= 0.0) error->all(FLERR,"Illegal compute entropy/atom command; cutoff must be positive");
 
   cutoff2 = 0.;
   avg_flag = 0;
@@ -71,26 +70,17 @@ ComputeEntropyAtom(LAMMPS *lmp, int narg, char **arg) :
   int iarg = 5;
   while (iarg < narg) {
     if (strcmp(arg[iarg],"avg") == 0) {
-      if (iarg+2 > narg)
-        error->all(FLERR,"Illegal compute entropy/atom;"
-                   " missing arguments after avg");
-      if (strcmp(arg[iarg+1],"yes") == 0) avg_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) avg_flag = 0;
-      else error->all(FLERR,"Illegal compute entropy/atom;"
-                      " argument after avg should be yes or no");
+      if (iarg+3 > narg) error->all(FLERR,"Illegal compute entropy/atom command");
+      avg_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       cutoff2 = utils::numeric(FLERR,arg[iarg+2],false,lmp);
-      if (cutoff2 < 0.0) error->all(FLERR,"Illegal compute entropy/atom"
-                                    " command; negative cutoff2");
+      if (cutoff2 < 0.0) error->all(FLERR,"Illegal compute entropy/atom command; negative cutoff2");
       cutsq2 = cutoff2*cutoff2;
       iarg += 3;
     } else if (strcmp(arg[iarg],"local") == 0) {
-      if (strcmp(arg[iarg+1],"yes") == 0) local_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) local_flag = 0;
-      else error->all(FLERR,"Illegal compute entropy/atom;"
-                      " argument after local should be yes or no");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal compute entropy/atom command");
+      local_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
-    } else error->all(FLERR,"Illegal compute entropy/atom; argument after"
-                      " sigma and cutoff should be avg or local");
+    } else error->all(FLERR,"Illegal compute entropy/atom command");
   }
 
 
diff --git a/src/EXTRA-DUMP/dump_dcd.cpp b/src/EXTRA-DUMP/dump_dcd.cpp
index 97c9bec646..ec3973448a 100644
--- a/src/EXTRA-DUMP/dump_dcd.cpp
+++ b/src/EXTRA-DUMP/dump_dcd.cpp
@@ -258,9 +258,7 @@ int DumpDCD::modify_param(int narg, char **arg)
 {
   if (strcmp(arg[0],"unwrap") == 0) {
     if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
-    if (strcmp(arg[1],"yes") == 0) unwrap_flag = 1;
-    else if (strcmp(arg[1],"no") == 0) unwrap_flag = 0;
-    else error->all(FLERR,"Illegal dump_modify command");
+    unwrap_flag = utils::logical(FLERR,arg[1],false,lmp);
     return 2;
   }
   return 0;
diff --git a/src/EXTRA-DUMP/dump_xtc.cpp b/src/EXTRA-DUMP/dump_xtc.cpp
index 7de6d03561..94846671cd 100644
--- a/src/EXTRA-DUMP/dump_xtc.cpp
+++ b/src/EXTRA-DUMP/dump_xtc.cpp
@@ -24,19 +24,20 @@
 ------------------------------------------------------------------------- */
 
 #include "dump_xtc.h"
-#include <cmath>
 
-#include <cstring>
-#include <climits>
-#include "domain.h"
 #include "atom.h"
-#include "update.h"
-#include "group.h"
-#include "output.h"
-#include "force.h"
 #include "comm.h"
-#include "memory.h"
+#include "domain.h"
 #include "error.h"
+#include "force.h"
+#include "group.h"
+#include "memory.h"
+#include "output.h"
+#include "update.h"
+
+#include <climits>
+#include <cmath>
+#include <cstring>
 
 using namespace LAMMPS_NS;
 
@@ -278,9 +279,7 @@ int DumpXTC::modify_param(int narg, char **arg)
 {
   if (strcmp(arg[0],"unwrap") == 0) {
     if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
-    if (strcmp(arg[1],"yes") == 0) unwrap_flag = 1;
-    else if (strcmp(arg[1],"no") == 0) unwrap_flag = 0;
-    else error->all(FLERR,"Illegal dump_modify command");
+    unwrap_flag = utils::logical(FLERR,arg[1],false,lmp);
     return 2;
   } else if (strcmp(arg[0],"precision") == 0) {
     if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
diff --git a/src/EXTRA-FIX/fix_flow_gauss.cpp b/src/EXTRA-FIX/fix_flow_gauss.cpp
index 415f1eecc0..2f8de2e21a 100644
--- a/src/EXTRA-FIX/fix_flow_gauss.cpp
+++ b/src/EXTRA-FIX/fix_flow_gauss.cpp
@@ -91,9 +91,7 @@ FixFlowGauss::FixFlowGauss(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"energy") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal energy keyword");
-      if (strcmp(arg[iarg+1],"yes") == 0) workflag = true;
-      else if (strcmp(arg[iarg+1],"no") != 0)
-        error->all(FLERR,"Illegal energy keyword");
+      workflag = utils::logical(FLERR,arg[iarg+1],false,lmp) == 1;
       iarg += 2;
     } else error->all(FLERR,"Illegal fix flow/gauss command");
   }
diff --git a/src/EXTRA-FIX/fix_gld.cpp b/src/EXTRA-FIX/fix_gld.cpp
index 3f807d0f51..41585e4fd0 100644
--- a/src/EXTRA-FIX/fix_gld.cpp
+++ b/src/EXTRA-FIX/fix_gld.cpp
@@ -19,17 +19,18 @@
 
 #include "fix_gld.h"
 
+#include "atom.h"
+#include "comm.h"
+#include "error.h"
+#include "force.h"
+#include "group.h"
+#include "memory.h"
+#include "random_mars.h"
+#include "respa.h"
+#include "update.h"
+
 #include <cmath>
 #include <cstring>
-#include "atom.h"
-#include "force.h"
-#include "update.h"
-#include "respa.h"
-#include "comm.h"
-#include "random_mars.h"
-#include "memory.h"
-#include "error.h"
-#include "group.h"
 
 #define GLD_UNIFORM_DISTRO
 
@@ -128,26 +129,14 @@ FixGLD::FixGLD(LAMMPS *lmp, int narg, char **arg) :
 
   while (iarg < narg) {
     if (strcmp(arg[iarg],"zero") == 0) {
-      if (iarg+2 > narg) {
-        error->all(FLERR, "Illegal fix gld 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 gld command");
-      }
+      if (iarg+2 > narg) error->all(FLERR, "Illegal fix gld command");
+      zeroflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     }
     else if (strcmp(arg[iarg],"frozen") == 0) {
-       if (iarg+2 > narg) {
-          error->all(FLERR, "Illegal fix gld command");
-       }
-       if (strcmp(arg[iarg+1],"no") == 0) {
-         freezeflag = 0;
-       } else if (strcmp(arg[iarg+1],"yes") == 0) {
-         freezeflag = 1;
+       if (iarg+2 > narg) error->all(FLERR, "Illegal fix gld command");
+       freezeflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
+       if (freezeflag) {
          for (int i = 0; i < atom->nlocal; i++) {
            if (atom->mask[i] & groupbit) {
              for (int k = 0; k < 3*prony_terms; k=k+3)
@@ -158,8 +147,6 @@ FixGLD::FixGLD(LAMMPS *lmp, int narg, char **arg) :
              }
            }
          }
-       } else {
-          error->all(FLERR, "Illegal fix gld command");
        }
        iarg += 2;
     }
diff --git a/src/EXTRA-FIX/fix_npt_cauchy.cpp b/src/EXTRA-FIX/fix_npt_cauchy.cpp
index 6a7d91dd16..07077cdabb 100644
--- a/src/EXTRA-FIX/fix_npt_cauchy.cpp
+++ b/src/EXTRA-FIX/fix_npt_cauchy.cpp
@@ -297,9 +297,7 @@ FixNPTCauchy::FixNPTCauchy(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"mtk") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix npt/cauchy 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 npt/cauchy 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 npt/cauchy command");
@@ -318,27 +316,19 @@ FixNPTCauchy::FixNPTCauchy(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg],"scalexy") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix npt/cauchy 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 npt/cauchy 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 npt/cauchy 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 npt/cauchy 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 npt/cauchy 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 npt/cauchy 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 npt/cauchy 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 npt/cauchy 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 npt/cauchy command");
@@ -352,10 +342,8 @@ FixNPTCauchy::FixNPTCauchy(LAMMPS *lmp, int narg, char **arg) :
       alpha = utils::numeric(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"continue") == 0) {
-      if (strcmp(arg[iarg+1],"yes") != 0 && strcmp(arg[iarg+1],"no") != 0)
-        error->all(FLERR,"Illegal cauchystat continue value.  "
-                   "Must be 'yes' or 'no'");
-      restartPK = !strcmp(arg[iarg+1],"yes");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal fix npt/cauchy command");
+      restartPK = 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 npt/cauchy command");
diff --git a/src/EXTRA-FIX/fix_pafi.cpp b/src/EXTRA-FIX/fix_pafi.cpp
index 3b51906ae1..fbb6fb2971 100644
--- a/src/EXTRA-FIX/fix_pafi.cpp
+++ b/src/EXTRA-FIX/fix_pafi.cpp
@@ -103,16 +103,12 @@ FixPAFI::FixPAFI(LAMMPS *lmp, int narg, char **arg) :
   int iarg = 7;
   while (iarg < narg) {
     if (strcmp(arg[iarg],"overdamped") == 0) {
-      if (strcmp(arg[iarg+1],"no") == 0) od_flag = 0;
-      else if (strcmp(arg[iarg+1],"0") == 0) od_flag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) od_flag = 1;
-      else if (strcmp(arg[iarg+1],"1") == 0) od_flag = 1;
+      if (iarg+2 > narg) error->all(FLERR,"Illegal fix pafi command");
+      od_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"com") == 0) {
-      if (strcmp(arg[iarg+1],"no") == 0) com_flag = 0;
-      else if (strcmp(arg[iarg+1],"0") == 0) com_flag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) com_flag = 1;
-      else if (strcmp(arg[iarg+1],"1") == 0) com_flag = 1;
+      if (iarg+2 > narg) error->all(FLERR,"Illegal fix pafi command");
+      com_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix pafi command");
   }
diff --git a/src/FEP/compute_fep.cpp b/src/FEP/compute_fep.cpp
index 683fbe114a..787c8a29e6 100644
--- a/src/FEP/compute_fep.cpp
+++ b/src/FEP/compute_fep.cpp
@@ -124,18 +124,12 @@ ComputeFEP::ComputeFEP(LAMMPS *lmp, int narg, char **arg) :
 
   while (iarg < narg) {
     if (strcmp(arg[iarg],"tail") == 0) {
-      if (iarg+2 > narg) error->all(FLERR,"Illegal optional keyword "
-                                    "in compute fep");
-      if (strcmp(arg[iarg+1],"no") == 0) tailflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) tailflag = 1;
-      else error->all(FLERR,"Illegal optional keyword in compute fep");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal optional keyword in compute fep");
+      tailflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"volume") == 0) {
-      if (iarg+2 > narg) error->all(FLERR,"Illegal optional keyword "
-                                    "in compute fep");
-      if (strcmp(arg[iarg+1],"no") == 0) volumeflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) volumeflag = 1;
-      else error->all(FLERR,"Illegal optional keyword in compute fep");
+      if (iarg+2 > narg) error->all(FLERR,"Illegal optional keyword in compute fep");
+      volumeflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else
       error->all(FLERR,"Illegal optional keyword in compute fep");
diff --git a/src/FEP/fix_adapt_fep.cpp b/src/FEP/fix_adapt_fep.cpp
index a6891c8742..d43c053b9a 100644
--- a/src/FEP/fix_adapt_fep.cpp
+++ b/src/FEP/fix_adapt_fep.cpp
@@ -138,21 +138,15 @@ FixAdaptFEP::FixAdaptFEP(LAMMPS *lmp, int narg, char **arg) :
   while (iarg < narg) {
     if (strcmp(arg[iarg],"reset") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix adapt/fep 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/fep 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/fep 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/fep command");
+      scaleflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"after") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix adapt/fep command");
-      if (strcmp(arg[iarg+1],"no") == 0) afterflag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) afterflag = 1;
-      else error->all(FLERR,"Illegal fix adapt/fep command");
+      afterflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else error->all(FLERR,"Illegal fix adapt/fep command");
   }
diff --git a/src/H5MD/dump_h5md.cpp b/src/H5MD/dump_h5md.cpp
index 46c587a992..9517877053 100644
--- a/src/H5MD/dump_h5md.cpp
+++ b/src/H5MD/dump_h5md.cpp
@@ -16,23 +16,24 @@
    Contributing author: Pierre de Buyl (KU Leuven)
 ------------------------------------------------------------------------- */
 
-#include <cmath>
-#include <cstdio>
-
-#include <cstring>
-#include <climits>
-#include "ch5md.h"
 #include "dump_h5md.h"
-#include "domain.h"
+
 #include "atom.h"
-#include "update.h"
-#include "group.h"
-#include "output.h"
+#include "domain.h"
 #include "error.h"
 #include "force.h"
+#include "group.h"
 #include "memory.h"
+#include "output.h"
+#include "update.h"
 #include "version.h"
 
+#include <climits>
+#include <cmath>
+#include <cstring>
+
+#include "ch5md.h"
+
 using namespace LAMMPS_NS;
 
 #define MYMIN(a,b) ((a) < (b) ? (a) : (b))
@@ -152,25 +153,14 @@ DumpH5MD::DumpH5MD(LAMMPS *lmp, int narg, char **arg) : Dump(lmp, narg, arg)
         error->all(FLERR, "Invalid number of arguments in dump h5md");
       }
       box_is_set = true;
-      if (strcmp(arg[iarg+1], "yes")==0)
-        do_box=true;
-      else if (strcmp(arg[iarg+1], "no")==0)
-        do_box=false;
-      else
-        error->all(FLERR, "Illegal dump h5md command");
+      do_box = utils::logical(FLERR,arg[iarg+1],false,lmp) == 1;
       iarg+=2;
     } else  if (strcmp(arg[iarg], "create_group")==0) {
       if (iarg+1>=narg) {
         error->all(FLERR, "Invalid number of arguments in dump h5md");
       }
       create_group_is_set = true;
-      if (strcmp(arg[iarg+1], "yes")==0)
-        create_group=true;
-      else if (strcmp(arg[iarg+1], "no")==0) {
-        create_group=false;
-      }
-      else
-        error->all(FLERR, "Illegal dump h5md command");
+      create_group = utils::logical(FLERR,arg[iarg+1],false,lmp) == 1;
       iarg+=2;
     } else if (strcmp(arg[iarg], "author")==0) {
       if (iarg+1>=narg) {
diff --git a/src/KOKKOS/kokkos.cpp b/src/KOKKOS/kokkos.cpp
index aa435d5b0b..be32604f94 100644
--- a/src/KOKKOS/kokkos.cpp
+++ b/src/KOKKOS/kokkos.cpp
@@ -381,9 +381,7 @@ void KokkosLMP::accelerator(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"newton") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal package kokkos command");
-      if (strcmp(arg[iarg+1],"off") == 0) newtonflag = 0;
-      else if (strcmp(arg[iarg+1],"on") == 0) newtonflag = 1;
-      else error->all(FLERR,"Illegal package kokkos command");
+      newtonflag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"comm") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal package kokkos command");
@@ -459,21 +457,15 @@ void KokkosLMP::accelerator(int narg, char **arg)
     } else if ((strcmp(arg[iarg],"gpu/aware") == 0)
                || (strcmp(arg[iarg],"cuda/aware") == 0)) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal package kokkos command");
-      if (strcmp(arg[iarg+1],"off") == 0) gpu_aware_flag = 0;
-      else if (strcmp(arg[iarg+1],"on") == 0) gpu_aware_flag = 1;
-      else error->all(FLERR,"Illegal package kokkos command");
+      gpu_aware_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"pair/only") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal package kokkos command");
-      if (strcmp(arg[iarg+1],"off") == 0) pair_only_flag = 0;
-      else if (strcmp(arg[iarg+1],"on") == 0) pair_only_flag = 1;
-      else error->all(FLERR,"Illegal package kokkos command");
+      pair_only_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"neigh/thread") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal package kokkos command");
-      if (strcmp(arg[iarg+1],"off") == 0) neigh_thread = 0;
-      else if (strcmp(arg[iarg+1],"on") == 0) neigh_thread = 1;
-      else error->all(FLERR,"Illegal package kokkos command");
+      neigh_thread = utils::logical(FLERR,arg[iarg+1],false,lmp);
       neigh_thread_set = 1;
       iarg += 2;
     } else error->all(FLERR,"Illegal package kokkos command");
diff --git a/src/MC/fix_atom_swap.cpp b/src/MC/fix_atom_swap.cpp
index 84c060a557..76200dc614 100644
--- a/src/MC/fix_atom_swap.cpp
+++ b/src/MC/fix_atom_swap.cpp
@@ -160,15 +160,11 @@ void FixAtomSwap::options(int narg, char **arg)
       iarg += 2;
     } else if (strcmp(arg[iarg],"ke") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix atom/swap command");
-      if (strcmp(arg[iarg+1],"no") == 0) conserve_ke_flag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) conserve_ke_flag = 1;
-      else error->all(FLERR,"Illegal fix atom/swap command");
+      conserve_ke_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"semi-grand") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal fix atom/swap command");
-      if (strcmp(arg[iarg+1],"no") == 0) semi_grand_flag = 0;
-      else if (strcmp(arg[iarg+1],"yes") == 0) semi_grand_flag = 1;
-      else error->all(FLERR,"Illegal fix atom/swap command");
+      semi_grand_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"types") == 0) {
       if (iarg+3 > narg) error->all(FLERR,"Illegal fix atom/swap command");
diff --git a/src/MC/fix_charge_regulation.cpp b/src/MC/fix_charge_regulation.cpp
index 2497b3d976..078e7eb9db 100644
--- a/src/MC/fix_charge_regulation.cpp
+++ b/src/MC/fix_charge_regulation.cpp
@@ -1180,8 +1180,8 @@ void FixChargeRegulation::setThermoTemperaturePointer() {
   int ifix = -1;
   ifix = modify->find_fix(idftemp);
   if (ifix == -1) {
-    error->all(FLERR,
-               "fix charge/regulation regulation could not find a temperature fix id provided by tempfixid\n");
+    error->all(FLERR, "fix charge/regulation regulation could not find "
+               "a temperature fix id provided by tempfixid\n");
   }
   Fix *temperature_fix = modify->fix[ifix];
   int dim;
@@ -1198,8 +1198,7 @@ void FixChargeRegulation::assign_tags() {
     for (int i = 0; i < atom->nlocal; i++) maxtag = MAX(maxtag, tag[i]);
     maxtag_all = maxtag;
     MPI_Allreduce(&maxtag, &maxtag_all, 1, MPI_LMP_TAGINT, MPI_MAX, world);
-    if (maxtag_all >= MAXTAGINT)
-      error->all(FLERR, "New atom IDs exceed maximum allowed ID");
+    if (maxtag_all >= MAXTAGINT) error->all(FLERR, "New atom IDs exceed maximum allowed ID");
 
     tagint notag = 0;
     tagint notag_all;
@@ -1267,23 +1266,19 @@ void FixChargeRegulation::options(int narg, char **arg) {
   while (iarg < narg) {
 
     if (strcmp(arg[iarg], "lunit_nm") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       llength_unit_in_nm = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "acid_type") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       acid_type = utils::inumeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "base_type") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       base_type = utils::inumeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "pH") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       if (strstr(arg[iarg + 1],"v_") == arg[iarg + 1]) {
         pHstr = utils::strdup(&arg[iarg + 1][2]);
       } else {
@@ -1292,45 +1287,37 @@ void FixChargeRegulation::options(int narg, char **arg) {
       }
       iarg += 2;
     } else if (strcmp(arg[iarg], "pIp") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       pI_plus = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "pIm") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       pI_minus = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "pKa") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       pKa = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "pKb") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       pKb = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
 
     } else if (strcmp(arg[iarg], "temp") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       reservoir_temperature = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "pKs") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       pKs = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "tempfixid") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       idftemp = utils::strdup(arg[iarg+1]);
       setThermoTemperaturePointer();
       iarg += 2;
     } else if (strcmp(arg[iarg], "rxd") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       reaction_distance = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       if ((reaction_distance > domain->prd_half[0]) ||
           (reaction_distance > domain->prd_half[1]) ||
@@ -1342,61 +1329,44 @@ void FixChargeRegulation::options(int narg, char **arg) {
       }
       iarg += 2;
     } else if (strcmp(arg[iarg], "nevery") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       nevery = utils::inumeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "nmc") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       nmc = utils::inumeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "pmcmoves") == 0) {
-      if (iarg + 4 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 4 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       pmcmoves[0] = utils::numeric(FLERR, arg[iarg + 1], false, lmp);
       pmcmoves[1] = utils::numeric(FLERR, arg[iarg + 2], false, lmp);
       pmcmoves[2] = utils::numeric(FLERR, arg[iarg + 3], false, lmp);
       iarg += 4;
     } else if (strcmp(arg[iarg], "seed") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
       seed = utils::inumeric(FLERR, arg[iarg + 1], false, lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "tag") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
-      if (strcmp(arg[iarg + 1], "yes") == 0) {
-        add_tags_flag = true;
-      } else if (strcmp(arg[iarg + 1], "no") == 0) {
-        add_tags_flag = false;
-      } else error->all(FLERR, "Illegal fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
+      add_tags_flag = utils::logical(FLERR,arg[iarg+1],false,lmp) == 1;
       iarg += 2;
     } else if (strcmp(arg[iarg], "onlysalt") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix charge/regulation command");
-      if (strcmp(arg[iarg + 1], "yes") == 0) {
-        only_salt_flag = true;
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
+      only_salt_flag = utils::logical(FLERR,arg[iarg+1],false,lmp) == 1;
+      iarg += 2;
+      if (only_salt_flag) {
         // need to specify salt charge
-        if (iarg + 4 > narg)
-          error->all(FLERR, "Illegal fix charge/regulation command");
-        salt_charge[0] = utils::inumeric(FLERR, arg[iarg + 2], false, lmp);
-        salt_charge[1] = utils::inumeric(FLERR, arg[iarg + 3], false, lmp);
-        iarg += 4;
-      } else if (strcmp(arg[iarg + 1], "no") == 0) {
-        only_salt_flag = false;
+        if (iarg + 2 > narg) error->all(FLERR, "Illegal fix charge/regulation command");
+        salt_charge[0] = utils::inumeric(FLERR, arg[iarg], false, lmp);
+        salt_charge[1] = utils::inumeric(FLERR, arg[iarg + 1], false, lmp);
         iarg += 2;
-      } else error->all(FLERR, "Illegal fix charge/regulation command");
-
+      }
     } else if (strcmp(arg[iarg], "group") == 0) {
-      if (iarg + 2 > narg)
-        error->all(FLERR, "Illegal fix fix charge/regulation command");
+      if (iarg + 2 > narg) error->all(FLERR, "Illegal fix fix charge/regulation command");
       if (ngroups >= ngroupsmax) {
         ngroupsmax = ngroups + 1;
         groupstrings = (char **)
-          memory->srealloc(groupstrings,
-                           ngroupsmax * sizeof(char *),
-                           "fix_charge_regulation:groupstrings");
+          memory->srealloc(groupstrings, ngroupsmax * sizeof(char *), "fix_charge_regulation:groupstrings");
       }
       groupstrings[ngroups] = utils::strdup(arg[iarg+1]);
       ngroups++;
diff --git a/src/MOLFILE/dump_molfile.cpp b/src/MOLFILE/dump_molfile.cpp
index c1c4120405..052fb444a4 100644
--- a/src/MOLFILE/dump_molfile.cpp
+++ b/src/MOLFILE/dump_molfile.cpp
@@ -421,9 +421,7 @@ int DumpMolfile::modify_param(int narg, char **arg)
 {
   if (strcmp(arg[0],"unwrap") == 0) {
     if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
-    if (strcmp(arg[1],"yes") == 0) unwrap_flag = 1;
-    else if (strcmp(arg[1],"no") == 0) unwrap_flag = 0;
-    else error->all(FLERR,"Illegal dump_modify command");
+    unwrap_flag = utils::logical(FLERR,arg[1],false,lmp);
     return 2;
 
   } else if (strcmp(arg[0],"element") == 0) {
diff --git a/src/NETCDF/dump_netcdf.cpp b/src/NETCDF/dump_netcdf.cpp
index cd7783a0aa..5702c94499 100644
--- a/src/NETCDF/dump_netcdf.cpp
+++ b/src/NETCDF/dump_netcdf.cpp
@@ -871,19 +871,13 @@ int DumpNetCDF::modify_param(int narg, char **arg)
   int iarg = 0;
   if (strcmp(arg[iarg],"double") == 0) {
     iarg++;
-    if (iarg >= narg)
-      error->all(FLERR,"expected 'yes' or 'no' after 'double' keyword.");
-    if (strcmp(arg[iarg],"yes") == 0) {
-      double_precision = true;
-    } else if (strcmp(arg[iarg],"no") == 0) {
-      double_precision = false;
-    } else error->all(FLERR,"expected 'yes' or 'no' after 'double' keyword.");
+    if (iarg >= narg) error->all(FLERR,"expected 'yes' or 'no' after 'double' keyword.");
+    double_precision = utils::logical(FLERR,arg[iarg],false,lmp) == 1;
     iarg++;
     return 2;
   } else if (strcmp(arg[iarg],"at") == 0) {
     iarg++;
-    if (iarg >= narg)
-      error->all(FLERR,"expected additional arg after 'at' keyword.");
+    if (iarg >= narg) error->all(FLERR,"expected additional arg after 'at' keyword.");
     framei = utils::inumeric(FLERR,arg[iarg],false,lmp);
     if (framei == 0) error->all(FLERR,"frame 0 not allowed for 'at' keyword.");
     else if (framei < 0) framei--;
@@ -891,13 +885,8 @@ int DumpNetCDF::modify_param(int narg, char **arg)
     return 2;
   } else if (strcmp(arg[iarg],"thermo") == 0) {
     iarg++;
-    if (iarg >= narg)
-      error->all(FLERR,"expected 'yes' or 'no' after 'thermo' keyword.");
-    if (strcmp(arg[iarg],"yes") == 0) {
-      thermo = true;
-    } else if (strcmp(arg[iarg],"no") == 0) {
-      thermo = false;
-    } else error->all(FLERR,"expected 'yes' or 'no' after 'thermo' keyword.");
+    if (iarg >= narg) error->all(FLERR,"expected 'yes' or 'no' after 'thermo' keyword.");
+    thermo = utils::logical(FLERR,arg[iarg],false,lmp) == 1;
     iarg++;
     return 2;
   } else return 0;
diff --git a/src/NETCDF/dump_netcdf_mpiio.cpp b/src/NETCDF/dump_netcdf_mpiio.cpp
index 4179b362c8..a6c3c535c9 100644
--- a/src/NETCDF/dump_netcdf_mpiio.cpp
+++ b/src/NETCDF/dump_netcdf_mpiio.cpp
@@ -866,19 +866,13 @@ int DumpNetCDFMPIIO::modify_param(int narg, char **arg)
   int iarg = 0;
   if (strcmp(arg[iarg],"double") == 0) {
     iarg++;
-    if (iarg >= narg)
-      error->all(FLERR,"expected 'yes' or 'no' after 'double' keyword.");
-    if (strcmp(arg[iarg],"yes") == 0) {
-      double_precision = true;
-    } else if (strcmp(arg[iarg],"no") == 0) {
-      double_precision = false;
-    } else error->all(FLERR,"expected 'yes' or 'no' after 'double' keyword.");
+    if (iarg >= narg) error->all(FLERR,"expected 'yes' or 'no' after 'double' keyword.");
+    double_precision = utils::logical(FLERR,arg[iarg],false,lmp) == 1;
     iarg++;
     return 2;
   } else if (strcmp(arg[iarg],"at") == 0) {
     iarg++;
-    if (iarg >= narg)
-      error->all(FLERR,"expected additional arg after 'at' keyword.");
+    if (iarg >= narg) error->all(FLERR,"expected additional arg after 'at' keyword.");
     framei = utils::inumeric(FLERR,arg[iarg],false,lmp);
     if (framei == 0) error->all(FLERR,"frame 0 not allowed for 'at' keyword.");
     else if (framei < 0) framei--;
@@ -886,13 +880,8 @@ int DumpNetCDFMPIIO::modify_param(int narg, char **arg)
     return 2;
   } else if (strcmp(arg[iarg],"thermo") == 0) {
     iarg++;
-    if (iarg >= narg)
-      error->all(FLERR,"expected 'yes' or 'no' after 'thermo' keyword.");
-    if (strcmp(arg[iarg],"yes") == 0) {
-      thermo = true;
-    } else if (strcmp(arg[iarg],"no") == 0) {
-      thermo = false;
-    } else error->all(FLERR,"expected 'yes' or 'no' after 'thermo' keyword.");
+    if (iarg >= narg) error->all(FLERR,"expected 'yes' or 'no' after 'thermo' keyword.");
+    thermo = utils::logical(FLERR,arg[iarg],false,lmp) == 1;
     iarg++;
     return 2;
   } else return 0;
diff --git a/src/VORONOI/compute_voronoi_atom.cpp b/src/VORONOI/compute_voronoi_atom.cpp
index 5808b8d17c..2be02e3d2a 100644
--- a/src/VORONOI/compute_voronoi_atom.cpp
+++ b/src/VORONOI/compute_voronoi_atom.cpp
@@ -109,15 +109,11 @@ ComputeVoronoi::ComputeVoronoi(LAMMPS *lmp, int narg, char **arg) :
       iarg += 2;
     } else if (strcmp(arg[iarg], "neighbors") == 0) {
       if (iarg + 2 > narg) error->all(FLERR,"Illegal compute voronoi/atom command");
-      if (strcmp(arg[iarg+1],"yes") == 0) faces_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) faces_flag = 0;
-      else error->all(FLERR,"Illegal compute voronoi/atom command");
+      faces_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg], "peratom") == 0) {
       if (iarg + 2 > narg) error->all(FLERR,"Illegal compute voronoi/atom command");
-      if (strcmp(arg[iarg+1],"yes") == 0) peratom_flag = 1;
-      else if (strcmp(arg[iarg+1],"no") == 0) peratom_flag = 0;
-      else error->all(FLERR,"Illegal compute voronoi/atom command");
+      peratom_flag = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     }
     else error->all(FLERR,"Illegal compute voronoi/atom command");
diff --git a/src/VTK/dump_vtk.cpp b/src/VTK/dump_vtk.cpp
index f323ce820f..a7aabe3f51 100644
--- a/src/VTK/dump_vtk.cpp
+++ b/src/VTK/dump_vtk.cpp
@@ -2070,9 +2070,7 @@ int DumpVTK::modify_param(int narg, char **arg)
 
   if (strcmp(arg[0],"binary") == 0) {
      if (narg < 2) error->all(FLERR,"Illegal dump_modify command [binary]");
-     if (strcmp(arg[1],"yes") == 0) binary = 1;
-     else if (strcmp(arg[1],"no") == 0) binary = 0;
-     else error->all(FLERR,"Illegal dump_modify command [binary]");
+     binary = utils::logical(FLERR,arg[1],false,lmp);
      return 2;
   }
 
diff --git a/src/input.cpp b/src/input.cpp
index bfd0d56632..296623932a 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -1622,16 +1622,10 @@ void Input::newton()
   int newton_pair=1,newton_bond=1;
 
   if (narg == 1) {
-    if (strcmp(arg[0],"off") == 0) newton_pair = newton_bond = 0;
-    else if (strcmp(arg[0],"on") == 0) newton_pair = newton_bond = 1;
-    else error->all(FLERR,"Illegal newton command");
+    newton_pair = newton_bond = utils::logical(FLERR,arg[0],false,lmp);
   } else if (narg == 2) {
-    if (strcmp(arg[0],"off") == 0) newton_pair = 0;
-    else if (strcmp(arg[0],"on") == 0) newton_pair= 1;
-    else error->all(FLERR,"Illegal newton command");
-    if (strcmp(arg[1],"off") == 0) newton_bond = 0;
-    else if (strcmp(arg[1],"on") == 0) newton_bond = 1;
-    else error->all(FLERR,"Illegal newton command");
+    newton_pair = utils::logical(FLERR,arg[0],false,lmp);
+    newton_bond = utils::logical(FLERR,arg[1],false,lmp);
   } else error->all(FLERR,"Illegal newton command");
 
   force->newton_pair = newton_pair;