在for或while循环中嵌套if for语句

Question

我对bash相当陌生，所以如果我的代码看起来不太好或者不正确，请放心。

我现在试着做一个脚本，它将平一个主机名，如果那个主机名没有响应，它将获取主机名的IP，并尝试它。似乎毫无意义，但我有自己的理由。

我遇到的问题是，我的脚本没有在脚本的末尾识别“已完成”。

#!/bin/bash
#while read hostname; do
for hostname in $(cat host.txt); do
ping -c1 $hostname 1>/dev/null 2>/dev/null
SUCCESS=$?
if [ $SUCCESS -eq 0 ]
        then
        echo "$hostname has replied"
else#[ $SUCCESS -ne 0 ]
        echo "Hostname didn't reply, trying IP"
        ip=`cat /etc/hosts | grep $hostname | awk '{print $1}' `
        ping -c1 $ip 1>/dev/null 2>/dev/null
        SUCCESS=$?
                if [ $SUCCESS -eq 0 ]
                        then
                        echo "$ip has replied"
                        echo "------------------------------"
                else
                        echo "$ip didn't reply"
                        echo "------------------------------"
                fi
done

Answer 1

我对代码进行了重新格式化，以更标准和更通用的方式缩进代码。我还添加了一些可能有助于人们学习基础知识的评论，比如4年前的@Root_。你可以检查一下：

#!/bin/bash

# I just used an editor that can do formatting of code.
# I asked it to reindent all lines within my settings.
# There are several programs to do this. I used vim.

for hostname in $(cat host.txt); do

    ping -c1 $hostname 1>/dev/null 2>/dev/null
    SUCCESS=$?

    # ping ended successfully?
    if [ $SUCCESS -eq 0 ] then
        echo "$hostname has replied"
    else
        echo "Hostname didn't reply, trying IP"

        ip=`cat /etc/hosts | grep $hostname | awk '{print $1}' `

        ping -c1 $ip 1>/dev/null 2>/dev/null
        SUCCESS=$?

        # ping ended successfully?
        if [ $SUCCESS -eq 0 ] then
            echo "$ip has replied"
            echo "------------------------------"
        else
            echo "$ip didn't reply"
            echo "------------------------------"
        fi
    fi
    # You missed this last "fi". With good indentation,
    # we see it easily. And with an editor that is done
    # for developers, it may even point us a place to
    # look for errors. In this case, the "done" was
    # written in red, which helped me asking 2 questions:
    # 1. Is this done in the right place? Where is its
    # corresponding "do"? (it is on on line 7 now)
    # 2. So, if the done is correct, what else is wrong?
    # Then, for the indentation I did, it was easy to see
    # the 'if' on line 13 did not have a 'fi'.
done