Shell learning process 1-How to output A-Z; spaces, line-wrapping conversions

There are a bunch of host addresses:
A.baidu.com
.
.
.
Z.baidu.com
How to extract the. Baidu.com letters from these data, such as: a b...z?

When you see the problem, you first think about how to generate the file with a script:

Ideas:

1. Definition suffix: suffix= ". baidu.com"

2. Output A-Z character and suffix: {A.. Z} $suffix

3. Space conversion Line

Question 1: How to output A-Z character:

Use {A.. Z} output a b c D ..... space between Z-characters

Problem 2:{a: Z} $suffix Output text: a.baidu.com b.baidu.com.....z.baidu.com, string space delimited. How are line breaks delimited?

Use tr ' \ n '

Test file generation succeeded.

The script is as follows:

#!/bin/bash

suffix= ". Baidu.com"

echo {A.. Z} $suffix |tr ' \ n ' > Hosts.txt

Back to the question: Advance letter A-Z:

Ideas: 1, using awk: delimited string, advance first segment ($)

2. Use tr ' \ n ' to turn line breaks into spaces for a-Z character line display

Awk-f '. ' ' {print $} ' hosts.txt | Tr ' \ n '

Echo

Shell learning process 1-How to output A-Z; spaces, line-wrapping conversions