Conditional Structures

Intro

• If this happens (if) - Do this If this either happens (elif) - Do this If none of the previous (else) - Do this fi

• Example:

#!/bin/bash

number=$RANDOM
echo -n "Type a number" # -n doesn't jump, stays in the same line
read player

if test $number -eq $player
then
    echo "Congrats!"
elif test $number -gt $player
then
    echo "Your number is lower"
else
    echo "Your number is greater"
fi

echo "the number of player is $player"
echo "the random number is $number"

Controlling inputs

#!/bin/bash

# we want two parameters
if test $# -ne 2
then
    echo "Usage: $0 <number1> <number2>"
    exit
fi

result=$(($1*$2))

echo "the result is $1 * $2 = $result"

Menus -> Case

• Alternative to switch from other languages

• Useful for menus in scripts

• echo "introduce option" read option case $option in 1) echo "option 1" ;; 2) echo "option 2" *) echo "introduce a valid option" ;; esac

#!/bin/bash

echo -n "Introduce an option [1-2]"
read option

case $option in
    1)
        echo "Option 1 chosen"
        ;;
    2)
        echo "Option 2 chosen"
        ;;
    *)
        echo "Wrong number selected, choose [1-2]"
        ;;
esac