diff --git a/.github/workflows/Intel.yml b/.github/workflows/Intel.yml
index 0e303c9d..6c3495e6 100644
--- a/.github/workflows/Intel.yml
+++ b/.github/workflows/Intel.yml
@@ -1,16 +1,16 @@
+# This is a GitHub actions workflow for the NCEPLIBS-grib_util project.
+#
+# This workflow builds with the intel compiler.
+#
+# Ed Hartnett 1/19/23
 name: Intel
 on:
   push:
     branches:
     - develop
-    paths-ignore:
-    - README.md
   pull_request:
     branches:
     - develop
-    paths-ignore:
-    - README.md
-
 
 # Use custom shell with -l so .bash_profile is sourced which loads intel/oneapi/setvars.sh
 # without having to do it in manually every step
diff --git a/.github/workflows/Linux_external.yml b/.github/workflows/Linux_external.yml
new file mode 100644
index 00000000..960ec74e
--- /dev/null
+++ b/.github/workflows/Linux_external.yml
@@ -0,0 +1,204 @@
+# This is a GitHub actions workflow for the NCEPLIBS-grib_util project.
+#
+# This workflow builds on Linux with latest versions of NCEPLIBS and
+# different versions jasper.
+#
+# Ed Hartnett 1/19/23
+name: Linux_external
+on:
+  push:
+    branches:
+    - develop
+  pull_request:
+    branches:
+    - develop
+
+jobs:
+  Linux_external:
+    runs-on: ubuntu-latest
+    env:
+      FC: gfortran-11
+      CC: gcc-11
+    strategy:
+      matrix:
+        g2-version: [develop, v3.4.x]
+        bacio-version: [2.5.0]
+        jasper-version: [2.0.33, 3.0.5, 4.0.0]
+        w3emc-version: [2.9.3]
+
+    steps:
+    - name: install-dependencies
+      run: |
+        sudo apt-get update &> /dev/null
+        sudo apt-get install libpng-dev libjpeg-dev 
+          
+    - name: cache-jasper
+      id: cache-jasper
+      uses: actions/cache@v2
+      with:
+        path: ~/jasper
+        key: jasper-Linux_versions-${{ matrix.jasper-version }}
+
+    - name: checkout-jasper
+      if: steps.cache-jasper.outputs.cache-hit != 'true'
+      uses: actions/checkout@v2
+      with:
+        repository: jasper-software/jasper
+        path: jasper
+        ref: version-${{ matrix.jasper-version }}
+
+    - name: build-jasper
+      if: steps.cache-jasper.outputs.cache-hit != 'true'
+      run: |
+        cd jasper
+        mkdir b && cd b
+        cmake .. -DCMAKE_INSTALL_PREFIX=~/jasper
+        make -j2
+        make install
+
+    - name: cache-bacio
+      id: cache-bacio
+      uses: actions/cache@v2
+      with:
+        path: ~/bacio
+        key: bacio-${{ runner.os }}-v${{ matrix.bacio-version }}
+
+    - name: checkout-bacio
+      if: steps.cache-bacio.outputs.cache-hit != 'true'
+      uses: actions/checkout@v2
+      with:
+        repository: NOAA-EMC/NCEPLIBS-bacio
+        path: bacio
+        ref: v${{ matrix.bacio-version }}
+    
+    - name: build-bacio
+      if: steps.cache-bacio.outputs.cache-hit != 'true'
+      run: |
+        cd bacio
+        mkdir build && cd build
+        cmake .. -DCMAKE_INSTALL_PREFIX=~/bacio
+        make -j2
+        make install
+
+    - name: cache-sp
+      id: cache-sp
+      uses: actions/cache@v2
+      with:
+        path: ~/sp
+        key: sp-${{ runner.os }}-2.3.3-1
+
+    - name: checkout-sp
+      if: steps.cache-sp.outputs.cache-hit != 'true'
+      uses: actions/checkout@v2
+      with:
+        repository: NOAA-EMC/NCEPLIBS-sp
+        path: sp
+        ref: v2.3.3
+
+    - name: build-sp
+      if: steps.cache-sp.outputs.cache-hit != 'true'
+      run: |
+        cd sp
+        mkdir build
+        cd build
+        cmake .. -DCMAKE_INSTALL_PREFIX=~/sp
+        make -j2
+        make install
+          
+    - name: cache-w3emc
+      id: cache-w3emc
+      uses: actions/cache@v2
+      with:
+        path: ~/w3emc
+        key: w3emc-${{ runner.os }}-${{ matrix.w3emc-version }}-bacio-${{ matrix.bacio-version }}
+
+    - name: checkout-w3emc
+      if: steps.cache-w3emc.outputs.cache-hit != 'true'
+      uses: actions/checkout@v2
+      with:
+        repository: NOAA-EMC/NCEPLIBS-w3emc
+        path: w3emc
+        ref: v${{ matrix.w3emc-version }}
+
+    - name: build-w3emc
+      if: steps.cache-w3emc.outputs.cache-hit != 'true'
+      run: |
+        cd w3emc
+        mkdir build
+        cd build
+        cmake .. -DCMAKE_PREFIX_PATH=~/bacio -DCMAKE_INSTALL_PREFIX=~/w3emc
+        make -j2
+        make install
+          
+    - name: cache-ip
+      id: cache-ip
+      uses: actions/cache@v2
+      with:
+        path: ~/ip
+        key: ip-${{ runner.os }}-3.3.3
+
+    - name: checkout-ip
+      if: steps.cache-ip.outputs.cache-hit != 'true'
+      uses: actions/checkout@v2
+      with:
+        repository: NOAA-EMC/NCEPLIBS-ip
+        path: ip
+        ref: v3.3.3
+
+    - name: build-ip
+      if: steps.cache-ip.outputs.cache-hit != 'true'
+      run: |
+        cd ip
+        mkdir build
+        cd build
+        cmake .. -DCMAKE_INSTALL_PREFIX=~/ip -DCMAKE_PREFIX_PATH=~/sp
+        make -j2
+        make install
+          
+    - name: checkout-g2c
+      uses: actions/checkout@v2
+      with:
+        repository: NOAA-EMC/NCEPLIBS-g2c
+        path: g2c
+        ref: develop
+
+    - name: build-g2c
+      run: |
+        cd g2c
+        mkdir build
+        cd build
+        cmake -DCMAKE_INSTALL_PREFIX=~/g2c -DCMAKE_PREFIX_PATH="~/jasper" ..
+        make -j2
+        make install
+                 
+    - name: checkout-g2
+      if: steps.cache-g2.outputs.cache-hit != 'true'
+      uses: actions/checkout@v2
+      with:
+        repository: NOAA-EMC/NCEPLIBS-g2
+        path: g2
+        ref: ${{ matrix.g2-version }}
+
+    - name: build-g2
+      run: |
+        cd g2
+        mkdir build
+        cd build
+        cmake -DCMAKE_INSTALL_PREFIX=~/g2 -DCMAKE_PREFIX_PATH="~/bacio;~/jasper;~/w3emc;~/g2c" ..
+        make -j2
+        make install
+                 
+    - name: checkout-grib_utils
+      uses: actions/checkout@v2
+      with: 
+        path: grib_utils
+
+    - name: build-grib_utils
+      run: |
+        cd grib_utils
+        mkdir build && cd build
+        export LD_LIBRARY_PATH=/home/runner/jasper/lib
+        export PATH="~/g2c/bin:$PATH"
+        cmake -DCMAKE_PREFIX_PATH="~/bacio;~/jasper;~/sp;~/ip;~/w3emc;~/g2;~/g2c" ..
+        make -j2 VERBOSE=1
+        ctest --output-on-failure --rerun-failed --verbose
diff --git a/.github/workflows/Linux_versions.yml b/.github/workflows/Linux_versions.yml
index e4358957..ac4e35b8 100644
--- a/.github/workflows/Linux_versions.yml
+++ b/.github/workflows/Linux_versions.yml
@@ -1,15 +1,17 @@
+# This is a GitHub actions workflow for the NCEPLIBS-grib_util project.
+#
+# This workflow builds on Linux with different versions of dependent
+# packages.
+#
+# Ed Hartnett 1/19/23
 name: Linux_versions
 on:
   push:
     branches:
     - develop
-    paths-ignore:
-    - README.md
   pull_request:
     branches:
     - develop
-    paths-ignore:
-    - README.md
 
 jobs:
   Linux_versions:
diff --git a/.github/workflows/MacOS.yml b/.github/workflows/MacOS.yml
index 0de66dd1..8938eb60 100644
--- a/.github/workflows/MacOS.yml
+++ b/.github/workflows/MacOS.yml
@@ -1,15 +1,16 @@
+# This is a GitHub actions workflow for the NCEPLIBS-grib_util project.
+#
+# This workflow builds on MacOS.
+#
+# Ed Hartnett 1/19/23
 name: MacOS
 on:
   push:
     branches:
     - develop
-    paths-ignore:
-    - README.md
   pull_request:
     branches:
     - develop
-    paths-ignore:
-    - README.md
 
 jobs:
   MacOS: 
diff --git a/.github/workflows/developer.yml b/.github/workflows/developer.yml
index 629ae9d4..7d943c9c 100644
--- a/.github/workflows/developer.yml
+++ b/.github/workflows/developer.yml
@@ -1,15 +1,18 @@
+# This is a GitHub actions CI workflow for the NCEPLIBS-grib_util
+# project.
+#
+# This workflow tests the build as a developer would do it, with
+# address sanitizer and documentation build.
+#
+# Ed Hartnett 1/9/23
 name: developer
 on:
   push:
     branches:
     - develop
-    paths-ignore:
-    - README.md
   pull_request:
     branches:
     - develop
-    paths-ignore:
-    - README.md
 
 jobs:
   developer:
@@ -34,7 +37,7 @@ jobs:
       with:
         repository: jasper-software/jasper
         path: jasper
-        ref: version-2.0.33
+        ref: version-3.0.5
 
     - name: cache-jasper
       id: cache-jasper
@@ -67,14 +70,23 @@ jobs:
         make -j2
         make install
 
+    - name: cache-sp
+      id: cache-sp
+      uses: actions/cache@v2
+      with:
+        path: ~/sp
+        key: sp-developer-${{ runner.os }}-2.3.3
+
     - name: checkout-sp
+      if: steps.cache-sp.outputs.cache-hit != 'true'
       uses: actions/checkout@v2
       with:
         repository: NOAA-EMC/NCEPLIBS-sp
         path: sp
-        ref: develop
+        ref: v2.3.3
 
     - name: build-sp
+      if: steps.cache-sp.outputs.cache-hit != 'true'
       run: |
         cd sp
         mkdir build
@@ -144,6 +156,7 @@ jobs:
         mkdir build
         cd build
         echo $LD_LIBRARY_PATH
+        export PATH="~/g2c/bin:$PATH"
         pwd
         cmake -DCMAKE_INSTALL_PREFIX=~/g2 -DCMAKE_PREFIX_PATH="~/bacio;~/jasper;~/w3emc;~/g2c" ..
         make -j2
@@ -160,6 +173,7 @@ jobs:
         mkdir build && cd build
         ls -l ~/jasper/lib
         export LD_LIBRARY_PATH=/home/runner/jasper/lib
+        export PATH="~/g2c/bin:$PATH"
         cmake -DENABLE_DOCS=ON -DCMAKE_BUILD_TYPE=Debug -DCMAKE_PREFIX_PATH="~/bacio;~/jasper;~/sp;~/ip;~/w3emc;~/g2;~/g2c" -DCMAKE_Fortran_FLAGS="-fprofile-arcs -ftest-coverage -O0 -Wall" -DCMAKE_C_FLAGS="-fprofile-arcs -ftest-coverage -O0 -Wall" ..
         make -j2 VERBOSE=1
         ctest --output-on-failure --rerun-failed --verbose
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6d3e9d26..2728a439 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -43,6 +43,16 @@ find_package(w3emc 2.9.2 REQUIRED)
 find_package(g2 3.4.0 REQUIRED)
 if (g2_VERSION GREATER_EQUAL 3.5.0)
   find_package(g2c 1.7.0 REQUIRED)
+else()
+  find_package(g2c 1.7.0)
+endif()
+
+# See if the g2c_compare program is available.
+find_program(G2C_COMPARE g2c_compare)
+if (G2C_COMPARE)
+  message(STATUS "g2c_compare found: ${G2C_COMPARE}")
+else()
+  message(STATUS "g2c_compare not found.")
 endif()
 
 # The name of the bacio library changed with the 2.5.0 release. The
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 8bc75289..0f3363e5 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -71,11 +71,16 @@ gu_copy_test_data(ref_gdaswave.t00z.wcoast.0p16.f000_2.grib2.idx)
 # Run these shell tests.
 gu_test(run_cnvgrib_tests)
 gu_test(run_copygb_tests)
-gu_test(run_copygb2_tests)
 gu_test(run_degrib2_tests)
 gu_test(run_grbindex_tests)
 gu_test(run_grb2index_tests)
 
+# This test depends on the g2c_compare utility, which may not be
+# present.
+if (G2C_COMPARE)
+  gu_test(run_copygb2_tests)
+endif()
+
 # Does the user want to get extra test files from the FTP site, and
 # run extra tests on them?
 if(FTP_TEST_FILES)
diff --git a/tests/run_copygb2_tests.sh b/tests/run_copygb2_tests.sh
index b15635a2..b94397d8 100755
--- a/tests/run_copygb2_tests.sh
+++ b/tests/run_copygb2_tests.sh
@@ -10,12 +10,8 @@ echo "*** Running copygb2 test"
 # Copy GRIB2 file.
 ../src/copygb2/copygb2 -x data/ref_gdaswave.t00z.wcoast.0p16.f000.grib2 test_gdaswave_2.grib2
 
-# Create an index of the copied file.
-../src/grb2index/grb2index test_gdaswave_2.grib2 test_gdaswave_2.idx
-
-# Check against expected output. First 120 bytes contain differences,
-# so ignore them.
-cmp -i 120 test_gdaswave_2.idx data/ref_gdaswave_2.idx
+# Are the files the same?
+g2c_compare -v data/ref_gdaswave.t00z.wcoast.0p16.f000.grib2 test_gdaswave_2.grib2
 
 echo "*** SUCCESS!"
 exit 0