---

cat > ~/bin/calc.sh << 'EOF'
#!/bin/bash
res=$1
shift
while [ $# -ge 2 ] ; do
  res=$(($res$1$2))
  shift 2
done
echo $res
EOF

chmod +x ~/bin/calc.sh



cat ~/bin/calc.sh
ls -l ~/bin/calc.sh


{
  echo "=== a) calc.sh 1 + 2 \\* 3 + 3 / 4 ==="
  ~/bin/calc.sh 1 + 2 \* 3 + 3 / 4

  echo "=== b) calc.sh 1 + 2 \\* 3 ==="
  ~/bin/calc.sh 1 + 2 \* 3

  echo "=== c) calc.sh 1 + 2*3 (без экранирования) ==="
  ~/bin/calc.sh 1 + 2*3

  echo "=== d) calc.sh 1+2 ==="
  ~/bin/calc.sh 1+2
} > ~/report_calc.txt

cat ~/report_calc.txt