In /usr/bin/exmendis line 28:
if [ -z $2 ]; then
        ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
if [ -z "$2" ]; then


In /usr/bin/exmendis line 30:
    echo -n "Your choices are: "
         ^-- SC2039: In POSIX sh, echo flags are undefined.


In /usr/bin/exmendis line 31:
    ls $EXTRAMENUDIR/*.menu | \
    ^---------------------^ SC2012: Use find instead of ls to better handle non-alphanumeric filenames.


In /usr/bin/exmendis line 33:
    echo -n "Extra menu name? "
         ^-- SC2039: In POSIX sh, echo flags are undefined.


In /usr/bin/exmendis line 34:
    read MENUNAME
    ^--^ SC2162: read without -r will mangle backslashes.


In /usr/bin/exmendis line 39:
if ! [ -L $MENUDIR/$MENUNAME.menu ]; then
          ^------^ SC2086: Double quote to prevent globbing and word splitting.
                   ^-------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
if ! [ -L "$MENUDIR"/"$MENUNAME".menu ]; then


In /usr/bin/exmendis line 40:
    if [ -e $EXTRAMENUDIR/$MENUNAME.menu ]; then
                          ^-------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
    if [ -e $EXTRAMENUDIR/"$MENUNAME".menu ]; then


In /usr/bin/exmendis line 48:
rm -f $MENUDIR/$MENUNAME.menu
      ^------^ SC2086: Double quote to prevent globbing and word splitting.
               ^-------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
rm -f "$MENUDIR"/"$MENUNAME".menu

For more information:
  https://www.shellcheck.net/wiki/SC2039 -- In POSIX sh, echo flags are undef...
  https://www.shellcheck.net/wiki/SC2012 -- Use find instead of ls to better ...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...