In /usr/bin/libftdi1-config line 18:
	exit $1
             ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
	exit "$1"


In /usr/bin/libftdi1-config line 27:
  -*=*) optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'` ;;
               ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  -*=*) optarg=$(echo "$1" | sed 's/[-_a-zA-Z0-9]*=//') ;;


In /usr/bin/libftdi1-config line 69:
	echo $prefix
             ^-----^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
	echo "$prefix"


In /usr/bin/libftdi1-config line 72:
	echo $exec_prefix
             ^----------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
	echo "$exec_prefix"

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...