diff --git a/bin/gencode b/bin/gencode
index b598ea8973..434417a396 100755
--- a/bin/gencode
+++ b/bin/gencode
@@ -16,7 +16,9 @@ if [[ -n $check ]]; then
     bin/gencode_docs_examples check
 fi
 
-venv/bin/pip3 freeze > $tmpfile
+venv_pip3=$(bin/which_venv_pip3)
+
+$venv_pip3 freeze > $tmpfile
 if ! diff etc/requirements.txt $tmpfile; then
     echo etc/requirements.txt differences found
     echo please run bin/setup_base
diff --git a/bin/presubmit b/bin/presubmit
new file mode 100755
index 0000000000..e8315b6a00
--- /dev/null
+++ b/bin/presubmit
@@ -0,0 +1,77 @@
+#!/bin/bash -e
+
+function banner() {
+  echo
+  echo
+  echo ===========================
+  echo "$*"
+  echo ===========================
+}
+
+function needs_covg_update() {
+  local project="$1"
+  local output=$(find "${project}/src" -name "*.java" -newer "${project}/build/reports/jacoco/test/jacocoTestReport.xml")
+  test -n "${output}"  # 0=needs, 1=does not need
+}
+
+function needs_gencode_update() {
+  bin/gencode check
+}
+
+function needs_gencode_seq_update() {
+  return 0  # needs
+}
+
+function reset_needs() {
+  needs="0"
+}
+
+function add_needs() {
+  needs=$["${needs}"+1]
+}
+
+function genscript() {
+  echo running: "$@"
+  local rc="$?"
+  "$@"
+  echo exit status: $rc
+  return $rc
+}
+
+#
+# Main
+#
+
+ROOT_DIR=$(realpath $(dirname $0)/..)
+cd $ROOT_DIR
+
+# Generate code coverage
+banner "Code Coverage"
+reset_needs 
+for project in pubber validator; do
+  needs_covg_update "${project}" && add_needs
+done
+
+if [[ ${needs} -gt 0 ]]; then
+  genscript $ROOT_DIR/bin/gencovg
+fi
+
+# Generate code from schemas
+banner "Gencode from schemas"
+reset_needs
+needs_gencode_update && add_needs
+
+if [[ ${needs} -gt 0 ]]; then
+  genscript $ROOT_DIR/bin/gencode
+fi
+
+# Generate code for sequencer.md
+banner "Gencode for sequencer.md"
+reset_needs
+needs_gencode_seq_update && add_needs
+
+if [[ ${needs} -gt 0 ]]; then
+  genscript $ROOT_DIR/bin/gencode_seq
+fi
+
+# Done
diff --git a/bin/setup_base b/bin/setup_base
index a89ad3fa3c..acb50f8f79 100755
--- a/bin/setup_base
+++ b/bin/setup_base
@@ -5,4 +5,5 @@ sudo apt-get install -y hxtools moreutils expect mosquitto mosquitto-clients
 python3 --version
 python3 -m venv venv
 
-venv/bin/pip3 install -r etc/requirements.txt
+venv_pip3=$($(dirname $0)/which_venv_pip3)
+${venv_pip3} install -r etc/requirements.txt
diff --git a/bin/which_venv_pip3 b/bin/which_venv_pip3
new file mode 100755
index 0000000000..3a37691350
--- /dev/null
+++ b/bin/which_venv_pip3
@@ -0,0 +1,10 @@
+#!/bin/bash -e
+for f in venv/bin/pip3 $HOME/venv/bin/pip3; do
+  if [[ -x "$f" ]]; then
+    echo "$f"
+    exit 0
+  fi
+done
+
+>&2 echo Cannot find venv
+false