secondary interface

Secondary interface是指在某个设备或系统中，除主要接口（Primary interface）之外的另一种接口。主要接口通常是设备或系统的主要功能接口，而次要接口则提供了额外的功能或扩展接口，以支持更多的特定用途或应用场景。

在计算机系统中，次要接口通常是指除主处理器和主内存之外的其他接口，例如外部设备接口、扩展插槽、网络接口等。这些次要接口可以扩展计算机系统的功能和性能，使其更加灵活和多样化。

在通信系统中，次要接口通常是指除主通信接口之外的其他接口，例如备用接口、控制接口、调试接口等。这些次要接口可以增强通信系统的可靠性和可维护性，提高系统的运行效率和稳定性。

总之，次要接口（Secondary interface）是指在某个设备或系统中，除主要接口（Primary interface）之外的另一种接口。次要接口可以扩展设备或系统的功能和性能，增强其可靠性和可维护性。

相关问题

#!/bin/bash # Set the name of the primary network interface primary_interface="eth0" # Set the name of the secondary network interface secondary_interface="wlan0" # Set the IP address range of the local network local_network="192.168.1.0/24" # Keep running the script indefinitely while true; do # Check if the primary interface is up and connected to the local network if ip addr show $primary_interface up | grep -q $local_network; then # Add a new routing table for the primary interface echo "200 $primary_interface_table" >> /etc/iproute2/rt_tables # Add default route for primary interface to the new routing table primary_gateway=$(ip route show | grep "default" | grep "$primary_interface" | awk '{print $3}') ip route add default via $primary_gateway dev $primary_interface table $primary_interface_table # Add a rule to route all traffic from primary interface through the new routing table primary_ip=$(ip addr show $primary_interface | grep "inet\b" | awk '{print $2}' | cut -d/ -f1) ip rule add from $primary_ip table $primary_interface_table # Remove any existing default route for the secondary interface ip route del default dev $secondary_interface else # Remove any existing routing table for the primary interface existing_table=$(grep -n " $primary_interface_table" /etc/iproute2/rt_tables | cut -f1 -d:) if [ ! -z "$existing_table" ]; then sed -i "${existing_table}d" /etc/iproute2/rt_tables ip route flush table $primary_interface_table ip rule del table $primary_interface_table fi # Add default route for the secondary interface secondary_gateway=$(ip route show | grep "default" | grep "$secondary_interface" | awk '{print $3}') ip route add default via $secondary_gateway dev $secondary_interface fi # Wait for 1 second before checking the network interfaces again sleep 1 done 运行上述脚本，提示 ip: command line is not complete, try "help"

根据脚本的内容，出现 `ip: command line is not complete, try "help"` 错误的可能原因是 `$primary_interface_table` 变量未被定义。请确认你在脚本中是否定义了 `$primary_interface_table` 变量。如果没有定义，请在脚本中添加以下内容来定义变量：

# Set the name of the primary interface routing table
primary_interface_table="my_primary_table"

将 `my_primary_table` 替换为你想要使用的名称。

其实我想要实现的是: sh脚本监听网卡变动，如果eth0和wlan0都是通的，并且它们都是同一个网段，那么路由优先走eth0, 如果eth0被拔掉了，路由就自动切换到wanl0,之后如果再插回网线到eth0,则需要马上切换路由首选eth0,请问用脚本sh如何实现？

要实现这个功能，你需要使用脚本来监听网络接口的状态，并根据接口的状态更改路由表。你可以使用以下bash脚本来实现：

#!/bin/bash

# Set the name of the primary network interface
primary_interface="eth0"

# Set the name of the secondary network interface
secondary_interface="wlan0"

# Set the IP address range of the local network
local_network="192.168.1.0/24"

# Keep running the script indefinitely
while true; do

  # Check if the primary interface is up and connected to the local network
  if ip addr show $primary_interface up | grep -q $local_network; then
    # Add a new routing table for the primary interface
    echo "200 $primary_interface_table" >> /etc/iproute2/rt_tables
    # Add default route for primary interface to the new routing table
    primary_gateway=$(ip route show | grep "default" | grep "$primary_interface" | awk '{print $3}')
    ip route add default via $primary_gateway dev $primary_interface table $primary_interface_table
    # Add a rule to route all traffic from primary interface through the new routing table
    primary_ip=$(ip addr show $primary_interface | grep "inet\b" | awk '{print $2}' | cut -d/ -f1)
    ip rule add from $primary_ip table $primary_interface_table
    # Remove any existing default route for the secondary interface
    ip route del default dev $secondary_interface
  else
    # Remove any existing routing table for the primary interface
    existing_table=$(grep -n " $primary_interface_table" /etc/iproute2/rt_tables | cut -f1 -d:)
    if [ ! -z "$existing_table" ]; then
      sed -i "${existing_table}d" /etc/iproute2/rt_tables
      ip route flush table $primary_interface_table
      ip rule del table $primary_interface_table
    fi
    # Add default route for the secondary interface
    secondary_gateway=$(ip route show | grep "default" | grep "$secondary_interface" | awk '{print $3}')
    ip route add default via $secondary_gateway dev $secondary_interface
  fi

  # Wait for 1 second before checking the network interfaces again
  sleep 1

done

此脚本将在一个无限循环中运行，并检查主要和次要网络接口的状态。如果主接口（eth0）处于活动状态并连接到本地网络，则将其设置为首选路由器，并将次要接口（wlan0）的默认路由从路由表中删除。如果主接口未连接到本地网络，则将其从路由表中删除，并将次要接口设置为默认路由器。

请注意，该脚本需要管理员权限才能运行。你可以使用“sudo”命令来运行它，如下所示：

sudo sh script.sh