Building LAMMPS with the USER-OMP package is broken in lammps-11Feb13 because of the difference between GNU sed and BSD sed.

user-omp_bsd.patch

diff --git a/src/USER-OMP/Install.sh b/src/USER-OMP/Install.sh
old mode 100644
new mode 100755
index b37fd00..dd87e8b
--- a/src/USER-OMP/Install.sh
+++ b/src/USER-OMP/Install.sh
@@ -4,7 +4,7 @@
 # do not install child files if parent does not exist
 
 for file in *_omp.cpp *_omp.h ; do
-  ofile=`echo $file | sed  -e 's,\(.*\)_omp\.\(h\|cpp\),\1.\2,'`
+  ofile=`echo $file | sed  -e 's/_omp\./\./'`
   if (test $1 = 1) then
     if (test $file = "thr_omp.h") || (test $file = "thr_omp.cpp") then
       :  # always install those files.
diff --git a/src/USER-OMP/Package.sh b/src/USER-OMP/Package.sh
index dee167c..2795c3b 100644
--- a/src/USER-OMP/Package.sh
+++ b/src/USER-OMP/Package.sh
@@ -9,7 +9,7 @@ for file in *_omp.cpp *_omp.h ; do
     continue
   fi
   # derive name of non-OpenMP version
-  ofile=`echo $file | sed   -e 's,\(.*\)_omp\.\(h\|cpp\),\1.\2,'`
+  ofile=`echo $file | sed  -e 's/_omp\./\./'`
   if (test ! -e ../$ofile) then
     if (test -e ../$file) then
       echo "  removing src/$file"