Same thing happens with -c option:
$ fmClientCli -c 23 terminate called after throwing an instance of 'std::out_of_range' what(): basic_string::substr Aborted (core dumped)
Same thing happens with -c option:
$ fmClientCli -c 23 :substr
terminate called after throwing an instance of 'std::out_of_range'
what(): basic_string:
Aborted (core dumped)