请确保使用sed的-i选项。

-i[SUFFIX], --in-place[=SUFFIX]
  edit files in place (makes backup if extension supplied)

sed -i "2i192.241.xx.xx  venus.example.com venus" /etc/hosts

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否则，

echo "192.241.xx.xx  venus.example.com venus" >> /etc/hosts

型
会将该行附加到文件末尾，这样就可以按预期工作。

如果你在Mac上或者你需要sudo权限，试试这个：

sudo -- sh -c -e "echo '192.34.0.03   subdomain.domain.com' >> /etc/hosts";

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它仍然会要求您输入密码。
另一种方式从@kainjow

echo '192.34.0.03 subdomain.domain.com' | sudo tee -a /etc/hosts

型

插入/更新条目

如果你想使用bash以编程方式插入/更新主机条目，这里有一个我写的脚本：

#!/bin/bash

# insert/update hosts entry
ip_address="192.168.x.x"
host_name="my.hostname.example.com"
# find existing instances in the host file and save the line numbers
matches_in_hosts="$(grep -n $host_name /etc/hosts | cut -f1 -d:)"
host_entry="${ip_address} ${host_name}"

echo "Please enter your password if requested."

if [ ! -z "$matches_in_hosts" ]
then
    echo "Updating existing hosts entry."
    # iterate over the line numbers on which matches were found
    while read -r line_number; do
        # replace the text of each line with the desired host entry
        sudo sed -i '' "${line_number}s/.*/${host_entry} /" /etc/hosts
    done <<< "$matches_in_hosts"
else
    echo "Adding new hosts entry."
    echo "$host_entry" | sudo tee -a /etc/hosts > /dev/null
fi

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该脚本旨在与OS X一起使用，但也可以在Linux上工作，只需稍作调整。

echo "127.0.0.1 localhost `hostname`">./temp_hosts
echo "192.241.xx.xx  venus.example.com">>./temp_hosts
cat /etc/hosts |tail -n +2 >>./temp_hosts
cat ./temp_hosts > /etc/hosts
rm ./temp_file

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我应该指出，sed（stream 编辑器）实际上并不是用来编辑文件的，尽管它可以用来编辑文件。（Standard sed没有内置的机制来写入标准输出以外的内容。）一个更合适的工具是ed。
下面的艾德脚本说“找到包含正则表达式/127.0.0.1/的行，并在下一行追加”（单独的句号告诉艾德停止追加）。

ed /etc/hosts <<-'EOF'
    /127.0.0.1/a
    192.241.xx.xx  venus.example.com
    .
    wq
EOF

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也就是说，你真的可以很简单地将这一行附加到/etc/hosts文件的 end：

echo '192.241.xx.xx  venus.example.com' >> /etc/hosts

型

可以使用sed，例如：

sed '/Venus/ a\  
192.241.xx.xx  venus.example.com venus' /etc/hosts

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我开发了一个用户友好的脚本，可以轻松地在主机文件中添加、删除和列出IP地址和主机名：

#!/bin/bash
# Created by Mohamad Hamouday
# Date: 2023-12-05
# Purpose: A script to add, remove, and list entries in the hosts file

# Function to add an entry to the hosts file
add_entry() {
    # Get user input for IP address and server name
    read -p "Enter IP address: " ip_address
    read -p "Enter server name: " server_name

    # Check if the input is not empty
    if [ -z "$ip_address" ] || [ -z "$server_name" ]; then
        echo "IP address and server name cannot be empty."
        exit 1
    fi

    # Append the entry to the hosts file
    echo "$ip_address $server_name" >> /etc/hosts

    echo "Entry added to /etc/hosts: $ip_address $server_name"
}

# Function to remove an entry from the hosts file
remove_entry() {
    # Get user input for IP address or server name to remove
    read -p "Enter IP address or server name to remove: " entry_to_remove

    # Check if the input is not empty
    if [ -z "$entry_to_remove" ]; then
        echo "Entry cannot be empty."
        exit 1
    fi

    # Check if the entry exists in the hosts file
    if grep -q "$entry_to_remove" /etc/hosts; then
        # Remove the entry from the hosts file using sed
        sed -i.bak -e "/$entry_to_remove/d" /etc/hosts

        echo "Entry removed from /etc/hosts: $entry_to_remove"
    else
        echo "Entry does not exist in /etc/hosts: $entry_to_remove"
    fi
}

# Function to list all active entries in the hosts file
list_entries() {
    echo "Non-commented entries in /etc/hosts:"
    grep -E -v '^\s*#' /etc/hosts
}

# Check if the script is executed with root privileges
if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root."
   exit 1
fi

# Display menu for user choice
echo "1. Add entry"
echo "2. Remove entry"
echo "3. List entries"
read -p "Enter your choice (1, 2, or 3): " choice

case $choice in
    1)
        add_entry
        ;;
    2)
        remove_entry
        ;;
    3)
        list_entries
        ;;
    *)
        echo "Invalid choice. Exiting."
        exit 1
        ;;
esac

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要执行它，只需运行：

sudo sh scriptname.sh

型

尝试使用root访问。

public void edithost() {
    sudo("echo " + "192.168.43.1     www.openrap.com openrap" + " >> /etc/hosts");
    sudo("echo " + "192.168.43.1  openrap.com openrap" + " >> /etc/hosts");
    sudo("echo " + "192.168.2.144  www.openrap.com openrap" + " >> /etc/hosts");
    sudo("echo " + "192.168.2.144  openrap.com openrap" + " >> /etc/hosts");
}

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sudo超级用户权限

public static void sudo(String... strings) {
    try {
        Process su = Runtime.getRuntime().exec("su");
        DataOutputStream outputStream = new DataOutputStream(su.getOutputStream());

        for (String s : strings) {
            outputStream.writeBytes(s + "\n");
            outputStream.flush();
        }

        outputStream.writeBytes("exit\n");
        outputStream.flush();
        try {
            su.waitFor();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        outputStream.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

型
这将把行附加到android中的主机