In /usr/bin/bison.yacc line 41:
          && { (PATH='/bin:/bin'; FPATH=$PATH; sh -c :) >/dev/null 2>&1 \
                ^--^ SC2030: Modification of PATH is local (to subshell caused by (..) group).
                                  ^---^ SC2034: FPATH appears unused. Verify use (or export if used externally).


In /usr/bin/bison.yacc line 46:
      for dir in $PATH; do
                 ^---^ SC2031: PATH was modified in a subshell. That change might be lost.


In /usr/bin/bison.yacc line 49:
        for exec_ext in ''; do
                        ^-- SC2041: This is a literal string. To run as a command, use $(..) instead of '..' . 


In /usr/bin/bison.yacc line 62:
    *) curr_executable=`pwd`/"$curr_executable" ;;
                       ^---^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    *) curr_executable=$(pwd)/"$curr_executable" ;;


In /usr/bin/bison.yacc line 68:
    lsline=`LC_ALL=C ls -l "$curr_executable"`
           ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    lsline=$(LC_ALL=C ls -l "$curr_executable")


In /usr/bin/bison.yacc line 71:
        linkdest=`echo "$lsline" | sed -n -e "$sed_linkdest"`
                 ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
        linkdest=$(echo "$lsline" | sed -n -e "$sed_linkdest")


In /usr/bin/bison.yacc line 74:
          *) curr_executable=`echo "$curr_executable" | sed -e "$sed_dirname"`/"$linkdest" ;;
                             ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
          *) curr_executable=$(echo "$curr_executable" | sed -e "$sed_dirname")/"$linkdest" ;;


In /usr/bin/bison.yacc line 79:
  curr_installdir=`echo "$curr_executable" | sed -e 's,/[^/]*$,,'`
                  ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  curr_installdir=$(echo "$curr_executable" | sed -e 's,/[^/]*$,,')


In /usr/bin/bison.yacc line 81:
  curr_installdir=`cd "$curr_installdir" && pwd`
                  ^----------------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  curr_installdir=$(cd "$curr_installdir" && pwd)


In /usr/bin/bison.yacc line 90:
    orig_last=`echo "$orig_installprefix" | sed -n -e 's,^.*/\([^/]*\)$,\1,p'`
              ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    orig_last=$(echo "$orig_installprefix" | sed -n -e 's,^.*/\([^/]*\)$,\1,p')


In /usr/bin/bison.yacc line 91:
    curr_last=`echo "$curr_installprefix" | sed -n -e 's,^.*/\([^/]*\)$,\1,p'`
              ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    curr_last=$(echo "$curr_installprefix" | sed -n -e 's,^.*/\([^/]*\)$,\1,p')


In /usr/bin/bison.yacc line 98:
    orig_installprefix=`echo "$orig_installprefix" | sed -e 's,/[^/]*$,,'`
                       ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    orig_installprefix=$(echo "$orig_installprefix" | sed -e 's,/[^/]*$,,')


In /usr/bin/bison.yacc line 99:
    curr_installprefix=`echo "$curr_installprefix" | sed -e 's,/[^/]*$,,'`
                       ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    curr_installprefix=$(echo "$curr_installprefix" | sed -e 's,/[^/]*$,,')


In /usr/bin/bison.yacc line 122:
bindir=`relocate "${exec_prefix}/bin"`
       ^-----------------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
bindir=$(relocate "${exec_prefix}/bin")

For more information:
  https://www.shellcheck.net/wiki/SC2034 -- FPATH appears unused. Verify use ...
  https://www.shellcheck.net/wiki/SC2041 -- This is a literal string. To run ...
  https://www.shellcheck.net/wiki/SC2030 -- Modification of PATH is local (to...