In /usr/bin/mkindex line 6:
  && { UNAMES=`uname -s`; test "x$UNAMES" = xULTRIX; } 2>/dev/null \
              ^--------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  && { UNAMES=$(uname -s); test "x$UNAMES" = xULTRIX; } 2>/dev/null \


In /usr/bin/mkindex line 7:
  && { RUNNING_SH5=true; export RUNNING_SH5; exec /bin/sh5 $0 ${1+"$@"}; }
                                                           ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
  && { RUNNING_SH5=true; export RUNNING_SH5; exec /bin/sh5 "$0" ${1+"$@"}; }


In /usr/bin/mkindex line 11:
  && { UNAMES=`uname -s`; test "x$UNAMES" = xAIX; } 2>/dev/null \
              ^--------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  && { UNAMES=$(uname -s); test "x$UNAMES" = xAIX; } 2>/dev/null \


In /usr/bin/mkindex line 12:
  && { RUNNING_BSH=true; export RUNNING_BSH; exec /bin/bsh $0 ${1+"$@"}; }
                                                           ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
  && { RUNNING_BSH=true; export RUNNING_BSH; exec /bin/bsh "$0" ${1+"$@"}; }


In /usr/bin/mkindex line 15:
progname=`basename $0`
^------^ SC2034: progname appears unused. Verify use (or export if used externally).
         ^-----------^ SC2006: Use $(...) notation instead of legacy backticked `...`.
                   ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
progname=$(basename "$0")


In /usr/bin/mkindex line 18:
    echo "Usage: `basename $0` file[.idx|.glo] ..." 1>&2
                 ^-----------^ SC2006: Use $(...) notation instead of legacy backticked `...`.
                           ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
    echo "Usage: $(basename "$0") file[.idx|.glo] ..." 1>&2


In /usr/bin/mkindex line 27:
dir=`pwd`
    ^---^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
dir=$(pwd)


In /usr/bin/mkindex line 32:
  destdir=`echo "$i" | sed 's/^[^\/]*$/./; s/\/[^\/]*$//'`
          ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  destdir=$(echo "$i" | sed 's/^[^\/]*$/./; s/\/[^\/]*$//')


In /usr/bin/mkindex line 35:
  FILENAME=`basename "$i" .idx`
           ^------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  FILENAME=$(basename "$i" .idx)

For more information:
  https://www.shellcheck.net/wiki/SC2034 -- progname appears unused. Verify u...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...