In /usr/bin/texindex line 29:
mydir=`cd \`dirname $0\` && pwd`
      ^------------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.
          ^----------^ SC2046: Quote this to prevent word splitting.
          ^----------^ SC2006: Use $(...) notation instead of legacy backticked `...`.
                   ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
mydir=$(cd $(`dirname" $")\` && pwd)


In /usr/bin/texindex line 52:
test -z "$awk_binary" && awk_binary=awk
                         ^--------^ SC2209: Use var=$(command) to assign output (or quote to assign string).


In /usr/bin/texindex line 115:
escaped0=`echo "$0" | sed 's,\\\\,\\\\\\\\,g'`
         ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
escaped0=$(echo "$0" | sed 's,\\\\,\\\\\\\\,g')

For more information:
  https://www.shellcheck.net/wiki/SC2046 -- Quote this to prevent word splitt...
  https://www.shellcheck.net/wiki/SC2209 -- Use var=$(command) to assign outp...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...