shell: Add --version support.

.gitattributes

 caucase/_version.py export-subst
+shell/caucase.sh export-subst

shell/caucase.sh

@@ -749,7 +749,7 @@ EOF
       status arg argc \
       ca_netloc ca_address ca_port ca_path \
       csr_id csr csr_path crl crt crt_path crt_dir key_path key serial \
-      csr_list_json
+      csr_list_json version
 
     while test $# -gt 0; do
       arg="$1"
@@ -760,6 +760,19 @@ EOF
           _usage
           return
         ;;
+        --version)
+          # shellcheck disable=SC2016
+          version='$Format:%H$'
+          if [ "x$(echo "$version" | base64)" = 'xJEZvcm1hdDolSCQK' ]; then
+            if command -v git > /dev/null; then
+              version="$(git describe --tags --dirty --always --long)"
+            else
+              version='unknown'
+            fi
+          fi
+          printf '%s\n' "$version"
+          return
+        ;;
         --ca-url)
           _needArg 1 || return 1
           ca_anon_url="$1"