如何更好、更简单地在 bash 中编写这个动画字符串？

Question

clear
echo "loading"
sleep 0.6
clear
echo "Loading"
sleep 0.6
clear
echo "lOading"
sleep 0.6
clear
echo "loAding"
sleep 0.6
clear
echo "loaDing"
sleep 0.6  
clear
echo "loadIng"
sleep 0.6  
clear
echo "loadiNg"
sleep 0.6
clear
echo "loadinG"
sleep 0.6
clear
echo "loading."
sleep 0.6
clear  
echo "loading.."
sleep 0.6
clear  
echo "loading..."
sleep 0.6
clear
echo "loading"
sleep 0.6
clear

Answer 1

你可以避免对不同的字母大小写组合进行硬编码，并通过使用 shell 的参数扩展功能依次对字符串进行切分，并把一个字符转为大写。

同样，您可以用来printf插入回车符来代替echo默认的换行符 - 这样，您就可以避免clear在每一步都必须调用。

例如：

#!/bin/bash

clear

str='loading'
dly=0.6

printf '%s\r' "$str"
sleep "$dly"

for ((i=0;i<${#str};i++)); do
  l=${str:0:i}; r=${str:i}
  printf '%s%s\r' "${l}" "${r^}"
  sleep "$dly"
done

for ellipsis in . .. ... "    "; do
  printf '%s%s\r' "${str}" "${ellipsis}"
  sleep "$dly"
done