bash if function in ubuntu code example

Example 1: else if statement bash syntax

#!/bin/bash
 
read -p "Enter your marks: " marks
 
if [ $marks -ge 80 ]
then
    echo "Very Good"
 
elif [ $marks -ge 50 ]
then
    echo "Good"
 
elif [ $marks -ge 33 ]
then
    echo "Just Satisfactory"
else
    echo "Not OK"
fi

Example 2: bash if statement

and - &&
or - ||

# and example
if [ -r $1 ] && [ -s $1 ]
then
echo This file is useful.
fi

# or example
if [ $USER == 'bob' ] || [ $USER == 'andy' ]
then
ls -alh
else
ls
fi