In /usr/bin/ps2pdf line 8:
ps2pdf="`dirname \"$0\"`/ps2pdf$version"
        ^--------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
ps2pdf="$(dirname \"$0\")/ps2pdf$version"

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