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[ Linux Command Manual](#) * * * ## What is hostname A hostname is a unique name that identifies a computer on a network. Just as every person has their own name, each computer needs a distinctive name to be recognized on the network. In Linux systems, the hostname is used for: * Identifying the local computer * Recognizing devices in network communication * Affecting the operation of certain network services * Displaying in the terminal prompt Hostnames are generally divided into three types: 1. **Static hostname**: Stored in configuration files, remains unchanged after system reboot 2. **Transient hostname**: Temporarily set during runtime, becomes invalid after reboot 3. **Pretty hostname**: A descriptive name that can include special characters (e.g., "My Laptop") * * * ## hostname Command Basic Syntax The basic usage format of the hostname command is as follows: hostname If executed without any parameters, the `hostname` command will display the current system's hostname: ## Example $ hostname ubuntu-server * * * ## Common Option Parameter Descriptions The hostname command supports various options to view and set different types of hostnames: | Option | Description | | --- | --- | | `-a`, `--alias` | Display the host's alias (if set) | | `-A`, `--all-fqdns` | Display FQDNs (Fully Qualified Domain Names) for all network interfaces | | `-b`, `--boot` | Use the default hostname if none is set | | `-d`, `--domain` | Display the DNS domain name | | `-f`, `--fqdn`, `--long` | Display FQDN (Fully Qualified Domain Name) | | `-F`, `--file` | Read the hostname from the specified file | | `-i`, `--ip-address` | Display the host's IP address | | `-I`, `--all-ip-addresses` | Display IP addresses for all network interfaces | | `-s`, `--short` | Display the short hostname (removing the domain part) | | `-y`, `--yp`, `--nis` | Display the NIS domain name | * * * ## Three Methods to Set Hostname ### 1. Temporarily Set Hostname (Invalid after reboot) ## Example sudo hostname new-hostname Example: ## Example $ sudo hostname test-server $ hostname test-server Note: The hostname set by this method will revert to the original after system reboot. ### 2. Permanently Set Hostname (Modify configuration file) In most modern Linux distributions (using systemd), you can permanently modify the hostname like this: ## Example sudo hostnamectl set-hostname new-hostname Example: ## Example $ sudo hostnamectl set-hostname production-server This command will modify both: * The `/etc/hostname` file * The system's static hostname ### 3. Manually Edit Configuration File You can also directly edit the hostname configuration file: 1. Edit the `/etc/hostname` file: sudo nano /etc/hostname Delete the original content and write only the new hostname 2. Update the `/etc/hosts` file, ensuring there is a line mapping the hostname to 127.0.0.1: 127.0.0.1 localhost new-hostname 3. Apply changes (no reboot needed): sudo systemctl restart systemd-hostnamed * * * ## View Different Types of Hostnames ### View Static Hostname ## Example hostnamectl --static # or cat/etc/hostname ### View Transient Hostname ## Example hostname # or hostnamectl --transient ### View Pretty Hostname ## Example hostnamectl --pretty ### View FQDN (Fully Qualified Domain Name) ## Example hostname-f # or hostnamectl --fqdn * * * ## Practical Application Examples ### Example 1: View complete host information of the current system ## Example $ hostnamectl Static hostname: ubuntu-server Icon name: computer-vm Chassis: vm Machine ID: 1a2b3c4d5e6f7g8h9i0j Boot ID: 1k2l3m4n5o6p7q8r9s0t Virtualization: kvm Operating System: Ubuntu 20.04 LTS Kernel: Linux 5.4.0-42-generic Architecture: x86-64 ### Example 2: Set both static and pretty hostnames simultaneously ## Example sudo hostnamectl set-hostname "server01"--pretty"Primary Web Server" ### Example 3: Obtain hostname information through the network ## Example $ hostname-i 192.168.1.100 $ hostname-I 192.168.1.100 10.0.0.100 * * * ## Common Issues and Solutions ### Issue 1: Hostname does not take effect after setting **Solution**: 1. Ensure the `/etc/hosts` file is also updated 2. Check if any other service (like NetworkManager) is overriding the hostname setting 3. Try rebooting the system or running: sudo systemctl restart systemd-hostnamed ### Issue 2: Hostname contains illegal characters **Solution**: * Hostnames can only contain: * Letters a-z * Numbers 0-9 * Hyphen (-) * Cannot start or end with a hyphen * Length is usually limited to 63 characters ### Issue 3: Network services cannot recognize the new hostname **Solution**: 1. Restart relevant network services: sudo systemctl restart networking 2. Clear DNS cache (if applicable) 3. Ensure the DNS server has been updated (if it's a server on the network) * * * ## Best Practice Recommendations 1. **Naming conventions**: * Use meaningful names, such as "web-prod-01", "db-backup-02" * Avoid special characters and underscores * Maintain consistency, especially in server clusters 2. **Multi-hostname environment**: * Use the static hostname as the primary identifier * Use the pretty hostname to provide a human-readable description * Add aliases for important servers via `/etc/hosts` 3. **Automated management**: * In cloud environments, use cloud-init to automatically set hostnames * Manage hostnames in bulk using configuration management tools (like Ansible) 4. **Documentation**: * Maintain documentation mapping hostnames to server roles * Use hostnames as identifiers in monitoring systems * * * ## Summary hostname is a fundamental yet important concept in Linux system administration. Through this article, you should have mastered: 1. Methods to view and set different types of hostnames 2. The correct process for permanently modifying hostnames 3. Solutions to common issues related to hostnames 4. Best practices for hostname management Remember, before modifying hostnames in a production environment, always assess potential impacts, especially in cluster environments where hostname changes might affect service discovery and monitoring systems. [ Linux Command Manual](#)