if [ "$X" -lt "0" ]

then

  echo "X is less than zero"

fi

if [ "$X" -gt "0" ]; then

  echo "X is more than zero"

fi

[ "$X" -le "0" ] &&

      echo "X is less than or equal to  zero"

[ "$X" -ge "0" ] &&

      echo "X is more than or equal to zero"

[ "$X" = "0" ] &&

      echo "X is the string or number "0""

[ "$X" = "hello" ] &&

      echo "X matches the string "hello""

[ "$X" != "hello" ] &&

      echo "X is not the string "hello""

[ -n "$X" ] &&

      echo "X is of nonzero length"

[ -f "$X" ] &&

      echo "X is the path of a real file" ||

      echo "No such file: $X"

[ -x "$X" ] &&

      echo "X is the path of an executable file"

[ "$X" -nt "/etc/passwd" ] &&

      echo "X is a file which is newer than /etc/passwd"