2-5 shell 流程控制

num1=100
num2=200

if [ $num1 -eq $num2 ]
then
    
    echo "num1 == num2"
    
elif [ $num1 -gt $num2 ]
then
    echo "num1 > num2"
    
else
    echo "num1 <= num2"
fi


array=("item1" "item2" "item3")

for (( i=0;i<${#array[@]};i++)) do
#${#array[@]}获取数组长度用于循环
    echo ${array[i]}
done

for element in ${array[@]}
#也可以写成for element in ${array[*]}
do
    echo $element
done


for i in "${!array[@]}";
do
    printf "%s\t%s\n" "$i" "${array[$i]}"
done


while [ $num1 -lt $num2 ]
do
    echo "num1 < num2"
    break
done



USER="testing"

case $USER in

rich | barbara)
echo "Welcome, $USER"
echo "Please enjoy your visit"
;;

testing)
echo "Special testing account"
;;

jessica)
echo "Do not forget to log off when you're done"
;;

*)
echo "Sorry, you are not allowed here"
;;
esac