Mastering Linux Bash Script: Elevating Docker Builds with If-Else Conditions and Network Troubleshooting Techniques

Here, I recommend a practical article: “Linux Series: If Else in Scripts” by [Kwan’s Troubled Shop].

This article provides a detailed introduction on how to use a Bash script, docker_build.sh, for Docker image building, incorporating if-else conditional judgments, directory switching, and version control, to enable a flexible build process. The script executes specific tasks based on different parameters, including the building of front-end and back-end services. The article also analyzes the script functionalities, such as conditional judgment, directory switching, version control, and Docker command usage, demonstrating practical application scenarios of the script. Furthermore, the article offers optimization suggestions for the script, including parameterized processing, error handling, logging, and parallel building, to enhance its robustness and execution efficiency. Overall, this script is an effective Docker build practice case, providing strong support for Continuous Integration/Continuous Deployment (CI/CD) processes.

In today’s network environment, network failures are unavoidable. When network issues arise, having the ability to quickly and effectively diagnose and troubleshoot is an essential skill for network administrators. This article will detail the steps and techniques for network troubleshooting, helping readers to handle network problems with ease.

I. Preliminary Troubleshooting Steps

When a network failure occurs, the first step is to conduct preliminary troubleshooting to promptly determine the general scope and possible causes of the problem.

1. Check Physical Connections

Ensure that all network devices (such as routers, switches, cables, etc.) are properly connected and operational. Here are some common inspection steps:

• Check if the network cable is loose or damaged.
• Verify that the power supply of network devices is normal.
• Check whether the device indicator lights show normal status.

2. Verify Network Configuration

Confirm that the network configuration is correct, including IP addresses, subnet masks, gateways, and DNS servers. You can use the following commands to check and set network configurations:

Code Language: bashCopy

# View IP address configurationifconfig (Linux) or ipconfig (Windows)# Set static IP address (example)sudo ifconfig eth0 192.168.1.100 netmask 255.255.255.0sudo route add default gw 192.168.1.1

3. Test Basic Network Connection

Use the ping command to test local network connections and internet connections to eliminate disconnection or delay issues.

Code Language: bashCopy

# Test local network connectionping 192.168.1.1# Test internet connectionping www.google.com

II. In-depth Troubleshooting Steps

If preliminary troubleshooting does not resolve the issue, more in-depth troubleshooting is needed to further pinpoint the cause of the failure.

1. Check Routers and Switches

Ensure that the configuration and operational status of routers and switches are normal. You can view device logs, interface status, and routing tables by logging into the management interface of the devices.

Code Language: bashCopy

# View routing tableroute -n (Linux) or route print (Windows)

2. Check Network Traffic

Use network monitoring tools such as Wireshark or tcpdump to analyze network traffic and check for any abnormal traffic or packet loss.

Code Language: bashCopy

# Capture network trafficsudo tcpdump -i eth0# Analyze traffic using Wiresharkwireshark

3. Check Firewall Configuration

Ensure that the firewall configuration is correct and doesn’t incorrectly block legitimate network traffic. You can review firewall rules and logs to confirm whether network traffic is being blocked.

Code Language: bashCopy

# View firewall rules (Linux)sudo iptables -L# View firewall logssudo tail -f /var/log/syslog

III. Common Network Failures and Solutions

Below are some common network failures and their solutions:

1. IP Address Conflict

When multiple devices use the same IP address, network communication fails. The solution is to check and adjust the IP addresses of the devices to ensure they are not duplicated.

Code Language: bashCopy

# View IP addresses on the current networkarp -a

2. DNS Resolution Failure

Errors in DNS server configuration or server failures can lead to domain name resolution failures. The solution is to check DNS server settings to ensure the correct DNS servers are used.

Code Language: bashCopy

# Set DNS server (Linux)sudo nano /etc/resolv.conf# Add the following contentnameserver 8.8.8.8nameserver 8.8.4.4

3. Network Congestion

High data traffic can lead to network congestion, affecting network performance. The solution is to use traffic management tools to limit the bandwidth of certain applications, optimizing network traffic.

Code Language: bashCopy

# Use tc command to limit bandwidth (Linux)sudo tc qdisc add dev eth0 root tbf rate 10mbit burst 32kbit latency 400ms

4. Network Device Failure

Failures in network devices such as routers and switches can lead to network interruptions. The solution is to restart the devices or replace faulty ones.

Code Language: bashCopy

# Restart network service (Linux)sudo service network-manager restart

Conclusion

Network troubleshooting is an important task in network management. Mastering effective troubleshooting steps and techniques can quickly locate and resolve network issues. This article introduced preliminary and in-depth troubleshooting steps and provided solutions for common network failures. I hope this article can provide valuable references for readers and help improve the efficiency and skills of network management.