Consider macOS's uuidgen

src/_uuidgen

@@ -34,6 +34,12 @@
 #
 # ------------------------------------------------------------------------------
 
+case $OSTYPE in
+  (darwin*)
+    _arguments \
+      '-hdr[emit result in form suitable for copying into a header]'
+    ;;
+  (*)
     _arguments \
       '(- *)'{-h,--help}'[display this help]' \
       '(- *)'{-V,--version}'[display version]' \
@@ -45,6 +51,8 @@ _arguments \
       '(-C --count -s --sha1 -m --md5)'{-C,--count}'[generate more uuids in loop]:count' \
       '(-C --count -s --sha1 -m --md5)'{-s,--sha1}'[generate sha1 hash]' \
       '(-x --hex)'{-h,--hex}'[interpret name as hex string]'
+    ;;
+esac
 
 # Local Variables:
 # mode: Shell-Script