build.bash: added support to env that has no go.work file

build.bash

@@ -124,20 +124,39 @@ function buildLocal() {
 
 function exprPath() {
 	local path
-	path=$(grep -m1 -F "go-pkg/expr" go.work)
+	if path=$(grep 2>/dev/null -m1 -F "go-pkg/expr" go.work); then
 		echo ${path}
+	fi
 }
 
 function gitTag() {
-	local expr_path
+	local expr_path gopath gopkg mod
+	local tag
+
 	expr_path=$(exprPath)
+	if [[ "${expr_path}" ]]; then
 		tag=$(git -C "${expr_path}" tag -l --sort=-version:refname "v*"|head -1)
+	else
+		gopath=$(go env GOPATH)
+		gopkg="${gopath}/pkg/mod/git.portale-stac.it/go-pkg"
+		if cd "${gopkg}" 2>/dev/null; then
+			mod=$(ls -1v |grep expr@|tail -1)
+			tag=${mod##*@}
+			cd - >/dev/null
+		fi
+	fi
 	echo ${tag}
 }
 
 function createVersionSource() {
+set -x
 	local tag
 	tag=$(gitTag)
+	if [ -z "${tag}" ]; then
+		tag="n/a"
+	fi
+set +x
+
 	cat >version.go <<eot
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.