In /usr/bin/pfbtopfa line 7:
gs="`dirname \"$0\"`/$GS_EXECUTABLE"
    ^--------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
gs="$(dirname \"$0\")/$GS_EXECUTABLE"


In /usr/bin/pfbtopfa line 18:
    outfile=`basename "$1" \.pfb`.pfa
            ^-------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    outfile=$(basename "$1" \.pfb).pfa


In /usr/bin/pfbtopfa line 20:
    echo "Usage: `basename \"$0\"` input.pfb [output.pfa]" 1>&2
                 ^---------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    echo "Usage: $(basename \"$0\") input.pfb [output.pfa]" 1>&2

For more information:
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...