In /usr/bin/mk_modmap line 30:
! with `basename $0` by `whoami`@`hostname` `date`
       ^-----------^ SC2006: Use $(...) notation instead of legacy backticked `...`.
                 ^-- SC2086: Double quote to prevent globbing and word splitting.
                        ^------^ SC2006: Use $(...) notation instead of legacy backticked `...`.
                                 ^--------^ SC2006: Use $(...) notation instead of legacy backticked `...`.
                                            ^----^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
! with $(basename "$0") by $(whoami)@$(hostname) $(date)

For more information:
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...