bash Unix shell 脚本可以在没有 rev 的情况下反转字符串

Unix shell scripting to reverse a string without rev

提问by ari

I want to write a shell script that accepts a string as a command line argument and prints out what is entered in the reverse order with out using the rev command but rather reversing the letters one by one. how would I do that? so like if Flower is entered it will print out rewolF

我想编写一个 shell 脚本，它接受一个字符串作为命令行参数，并打印出以相反顺序输入的内容，而不使用 rev 命令，而是一个一个地反转字母。我该怎么做？所以就像如果输入 Flower 它将打印出 rewolF

Thanks

谢谢

回答by Gilles Quenot

A good subject for bashparameter expansion:

bash参数扩展的一个很好的主题：

#!/bin/bash

for ((i=${#1}; i>=0; i--)); do printf "${1:$i:1}"; done; echo

Example :

例子 ：

./script.sh foobar 

Output :

输出 ：

raboof

回答by michael501

s1='Flower'
a1=($(echo $s1|fold -w1 ))
for (( i=${#a1[@]}-1;i>=0;i--));do echo "$i=>${a1[i]}"; done
5=>r
4=>e
3=>w
2=>o
1=>l
0=>F