Detect if the tree command doesn't exist and print the workaround function/alias

scripts/quickstart.sh

@@ -21,6 +21,10 @@ case ${SHELL} in
     echo "unset EPICS_CA_ADDR_LIST"
     echo "unset EPICS_CA_AUTO_ADDR_LIST"
     echo 'mkdir -p ${IOC_DIR} ${SUPPORT_DIR}'
+    if ! command -v tree &> /dev/null
+    then
+        echo "tree() { find $1 -type d | grep -v git; }"
+    fi
     echo 'tree ${EPICS_DIR}'
     echo ""
     ;;
@@ -36,6 +40,10 @@ case ${SHELL} in
     echo "unsetenv EPICS_CA_ADDR_LIST"
     echo "unsetenv EPICS_CA_AUTO_ADDR_LIST"
     echo 'mkdir -p ${IOC_DIR} ${SUPPORT_DIR}'
+    if ! command -v tree &> /dev/null
+    then
+        echo "alias tree \"find \!* -type d | grep -v git\""
+    fi
     echo 'tree ${EPICS_DIR}'
     echo ""
     ;;