From gbs build wiki it says, if a Specific_Project/.gbs.conf file exists, the configuration in that file is used when building the project with GBS. If not, the default GBS configuration in ~/.gbs.conf is used.
How can I use a configuration file exist in a custom location like \home\pub\files.gbs.conf when building a project with gbs?
Use -c parameter
gbs -c <gbs-conf-file-full-path>