diff --git a/src/Makefile b/src/Makefile
index 674d7a808b..1070bd5025 100755
--- a/src/Makefile
+++ b/src/Makefile
@@ -18,7 +18,7 @@ PACKAGE = asphere class2 colloid dipole dsmc gpu granular \
 	  shock srd xtc
 
 PACKUSER = user-ackland user-atc user-awpmd user-cd-eam user-cg-cmm \
-	   user-eff user-ewaldn user-imd user-reaxc user-smd
+          user-eff user-ewaldn user-imd user-reaxc user-smd
 #	   user-cuda user-eff user-ewaldn user-imd user-reaxc user-smd
 
 PACKALL = $(PACKAGE) $(PACKUSER)
@@ -52,6 +52,7 @@ help:
 	@echo ''
 	@echo 'make package-update      replace src files with package files'
 	@echo 'make package-overwrite   replace package files with src files'
+	@echo 'make package-diff        diff src files against package files'
 	@echo ''
 	@echo 'make machine             build LAMMPS where machine is one of:'
 	@echo ''
@@ -126,6 +127,7 @@ package:
 	@echo ''
 	@echo 'make package-update      replace src files with package files'
 	@echo 'make package-overwrite   replace package files with src files'
+	@echo 'make package-diff        diff src files against package file'
 
 yes-all:
 	@for p in $(PACKALL); do $(MAKE) yes-$$p; done
@@ -161,10 +163,11 @@ no-%:
 	  cd $(NODIR); $(SHELL) Install.sh 0; cd ..; $(SHELL) Depend.sh 0; \
         fi;
 
-# status = list differences between src and package files
+# status = list src files that differ from package files
 # update = replace src files with newer package files
 # overwrite = overwrite package files with newer src files
 # regenerate = regenerate Makefile.package from Makefile.package.empty
+# diff = show differences between src and package files
 
 package-status:
 	@for p in $(PACKAGEUC); do $(SHELL) Package.sh $$p status; done
@@ -185,3 +188,9 @@ package-regenerate:
 	@cp Makefile.package.empty Makefile.package
 	@for p in $(PACKAGEUC); do $(SHELL) Package.sh $$p regenerate; done
 	@for p in $(PACKUSERUC); do $(SHELL) Package.sh $$p regenerate; done
+
+package-diff:
+	@for p in $(PACKAGEUC); do $(SHELL) Package.sh $$p diff; done
+	@echo ''
+	@for p in $(PACKUSERUC); do $(SHELL) Package.sh $$p diff; done
+
diff --git a/src/Package.sh b/src/Package.sh
index f1f7025d2f..b42494503d 100644
--- a/src/Package.sh
+++ b/src/Package.sh
@@ -1,5 +1,5 @@
 # Package.sh = package management, called from Makefile
-# Syntax: sh Package.sh DIR status/update/overwrite/regenerate
+# Syntax: sh Package.sh DIR status/update/overwrite/regenerate/diff
 
 # style used to translate dir name to package name
 
@@ -79,7 +79,7 @@ elif (test $2 = "overwrite") then
     echo "  $1 package is not installed, no action"
   fi
 
-# regenernate Makefile.package from Makefile.package.empty
+# regenenate Makefile.package from Makefile.package.empty
 # if installed:
 # re-install so Install.sh will edit Makefile.pacakge
 
@@ -87,4 +87,28 @@ elif (test $2 = "regenerate") then
   if (test $installed = 1) then
     /bin/sh Install.sh 1
   fi
+
+# diff
+# if installed:
+# show any differences between src files and package files
+
+elif (test $2 = "diff") then
+  if (test $installed = 1) then
+    echo "Installed YES: package $1"
+    for file in *.cpp *.h; do
+      if (test ! -e ../$file) then
+        echo "************************************************************************"
+        echo "  src/$file does not exist"
+        echo "************************************************************************"
+      elif (test "`diff --brief $file ../$file`" != "") then
+        echo "************************************************************************"
+        echo "diff $1/$file src/$file "
+        echo "************************************************************************"
+	diff $file  ../$file 
+      fi
+    done
+  fi
 fi
+
+
+
diff --git a/src/lammps.cpp b/src/lammps.cpp
index 9033a7d59d..548a69e36e 100644
--- a/src/lammps.cpp
+++ b/src/lammps.cpp
@@ -55,6 +55,8 @@ LAMMPS::LAMMPS(int narg, char **arg, MPI_Comm communicator)
   int inflag = 0;
   int screenflag = 0;
   int logflag = 0;
+  int partscreenflag = 0;
+  int partlogflag = 0;
   int cudaflag = -1;
   suffix = NULL;
   suffix_enable = 0;
@@ -94,6 +96,18 @@ LAMMPS::LAMMPS(int narg, char **arg, MPI_Comm communicator)
 	       strcmp(arg[iarg],"-e") == 0) {
       if (iarg+2 > narg) error->universe_all("Invalid command-line argument");
       iarg += 2;
+    } else if (strcmp(arg[iarg],"-pscreen") == 0 || 
+	       strcmp(arg[iarg],"-ps") == 0) {
+      if (iarg+2 > narg) 
+       error->universe_all("Invalid command-line argument");
+      partscreenflag = iarg + 1;
+      iarg += 2;
+    } else if (strcmp(arg[iarg],"-plog") == 0 || 
+	       strcmp(arg[iarg],"-pl") == 0) {
+      if (iarg+2 > narg) 
+       error->universe_all("Invalid command-line argument");
+      partlogflag = iarg + 1;
+      iarg += 2;
     } else if (strcmp(arg[iarg],"-cuda") == 0 || 
 	       strcmp(arg[iarg],"-c") == 0) {
       if (iarg+2 > narg) error->universe_all("Invalid command-line argument");
@@ -127,6 +141,16 @@ LAMMPS::LAMMPS(int narg, char **arg, MPI_Comm communicator)
   if (universe->existflag && inflag == 0)
     error->universe_all("Must use -in switch with multiple partitions");
 
+  // if no partition command-line switch, cannot use -pscreen option
+
+  if (universe->existflag == 0 && partscreenflag)
+    error->universe_all("Can only use -pscreen with multiple partitions");
+
+  // if no partition command-line switch, cannot use -plog option
+
+  if (universe->existflag == 0 && partlogflag)
+    error->universe_all("Can only use -plog with multiple partitions");
+
   // set universe screen and logfile
 
   if (universe->me == 0) {
@@ -194,37 +218,53 @@ LAMMPS::LAMMPS(int narg, char **arg, MPI_Comm communicator)
     MPI_Comm_split(universe->uworld,universe->iworld,0,&world);
     MPI_Comm_rank(world,&me);
 
-    if (me == 0) {
-      if (screenflag == 0) {
-	char str[32];
-	sprintf(str,"screen.%d",universe->iworld);
-	screen = fopen(str,"w");
-	if (screen == NULL) error->one("Cannot open screen file");
-      } else if (strcmp(arg[screenflag],"none") == 0)
+    if (me == 0)
+      if (partscreenflag == 0)
+       if (screenflag == 0) {
+         char str[32];
+         sprintf(str,"screen.%d",universe->iworld);
+         screen = fopen(str,"w");
+         if (screen == NULL) error->one("Cannot open screen file");
+       } else if (strcmp(arg[screenflag],"none") == 0)
+         screen = NULL;
+       else {
+         char str[128];
+         sprintf(str,"%s.%d",arg[screenflag],universe->iworld);
+         screen = fopen(str,"w");
+         if (screen == NULL) error->one("Cannot open screen file");
+       }
+      else if (strcmp(arg[partscreenflag],"none") == 0)
 	screen = NULL;
       else {
 	char str[128];
-	sprintf(str,"%s.%d",arg[screenflag],universe->iworld);
+	sprintf(str,"%s.%d",arg[partscreenflag],universe->iworld);
 	screen = fopen(str,"w");
 	if (screen == NULL) error->one("Cannot open screen file");
-      }
-    } else screen = NULL;
+      } else screen = NULL;
     
-    if (me == 0) {
-      if (logflag == 0) {
-	char str[32];
-	sprintf(str,"log.lammps.%d",universe->iworld);
-	logfile = fopen(str,"w");
-	if (logfile == NULL) error->one("Cannot open logfile");
-      } else if (strcmp(arg[logflag],"none") == 0)
+    if (me == 0)
+      if (partlogflag == 0)
+       if (logflag == 0) {
+         char str[32];
+         sprintf(str,"log.lammps.%d",universe->iworld);
+         logfile = fopen(str,"w");
+         if (logfile == NULL) error->one("Cannot open logfile");
+       } else if (strcmp(arg[logflag],"none") == 0)
+         logfile = NULL;
+       else {
+         char str[128];
+         sprintf(str,"%s.%d",arg[logflag],universe->iworld);
+         logfile = fopen(str,"w");
+         if (logfile == NULL) error->one("Cannot open logfile");
+       }
+      else if (strcmp(arg[partlogflag],"none") == 0)
 	logfile = NULL;
       else {
 	char str[128];
-	sprintf(str,"%s.%d",arg[logflag],universe->iworld);
+	sprintf(str,"%s.%d",arg[partlogflag],universe->iworld);
 	logfile = fopen(str,"w");
 	if (logfile == NULL) error->one("Cannot open logfile");
-      }
-    } else logfile = NULL;
+      } else logfile = NULL;
     
     if (me == 0) {
       infile = fopen(arg[inflag],"r");