创建 shell 脚本来打印工作日和周末

Question

如何使用 for 循环和 if 创建一个简单的程序。

我的代码：

for i in mon tue wed thurs fri sat 
do
   echo weekday: $i
   if [ $i == thurs ]   
   then
      echo weekend: $i+1
   fi
done

和输出：

weekday: mon
weekday: tue
weekday: wed
weekday: thurs
weekend: thurs+1
weekday: fri
weekday: sat

但是，我想要这样的输出：

weekday: mon
weekday: tue
weekday: wed
weekday: thurs
weekend: fri
weekend: sat

我错过了哪种语法？

Answer 1

给定代码：

for i in mon tue wed thurs fri sat 
do
 echo weekday: $i
  if [ $i == thurs ]    
    then
    echo weekend: $i+1
  fi
done

• echo weekday: $i每次迭代都会被调用
• 循环for每次迭代都会生成一个元素到i变量。i不是您所期望的数组索引

获得预期输出的不同方法：

1）进行字符串比较

for i in mon tue wed thurs fri sat 
do
    if [ $i == fri ] || [ $i == sat ]
    then
        echo weekend: $i
    else
        echo weekday: $i
    fi
done

2）使用字符串保存前缀，并根据条件进行修改

s='weekday'
for i in mon tue wed thurs fri sat 
do
    echo "$s: $i"
    if [ $i == thurs ]
    then
        s='weekend'
    fi
done

3）使用数组

days=(mon tue wed thurs fri sat)

for ((i=0; i<${#days[@]}; i++))
do
    if (( i < 4 ))
    then
        echo "weekday: ${days[$i]}"
    else
        echo "weekend: ${days[$i]}"
    fi
done