シェルスクリプト

if

if [ -e test.txt ]
then
  echo "test.txt exist"
fi

if - else

if [ -e test.txt ]
then
  echo "test.txt true"
else
  echo "test.txt false"
fi

if - elif - else

if [ -e test.txt ]
then
  echo "test.txt exist"
elif [ -e test2.txt ]
then
  echo "test2.txt exits"
fi