+# One can specify a user ID for changing ownership of output log/json files
+# - empty: depends on file existency
+# . yes? replacement, owner is unchanged
+# . no ? creation with root as user
+# - 0: this is the root user ID
+# - other: will corresponds (or not) to an existing user/group in the host
+# (the current user ID can be obtained with the command 'id -u')
+# Can be overriden by --user-id
+# Consider also that the default value below is overridable by a USER_ID env variable,
+# if nfvbench is run into a container, this information can be passed at its creation.
+# The overall precedence rule is: 'default_config (this) < env < config < command_line'
+user_id:
+
+# Similarly, the group ID is defined
+# Can be overriden by --group-id
+# Default may be set through env GROUP_ID
+# Caveat: user and group with a same name may have different numerical IDs
+# (the current group ID can be obtained with the command 'id -g')
+group_id:
+