+/*
+ * # readlink --version
+ * readlink (GNU coreutils) 6.10
+ * # readlink --help
+ * -f, --canonicalize
+ * canonicalize by following every symlink in
+ * every component of the given name recursively;
+ * all but the last component must exist
+ * -e, --canonicalize-existing
+ * canonicalize by following every symlink in
+ * every component of the given name recursively,
+ * all components must exist
+ * -m, --canonicalize-missing
+ * canonicalize by following every symlink in
+ * every component of the given name recursively,
+ * without requirements on components existence
+ * -n, --no-newline do not output the trailing newline
+ * -q, --quiet, -s, --silent suppress most error messages
+ * -v, --verbose report error messages
+ *
+ * bbox supports: -f -n -v (fully), -q -s (accepts but ignores)
+ */
+