If you’re using a Linux-based operating system, then you’re probably familiar with the /etc/hosts file. This file is used to map hostnames to IP addresses, and can be used to override the results from DNS lookups. In this blog post, we will discuss the purpose of the /etc/hosts file and how to use it in your system environment!
understanding /etc/hosts file in Linux
The /etc/hosts file is used to store mappings of hostnames to IP addresses. This file is consulted first when resolving hostnames, so it can be used to override the results from DNS lookups.
The format of this file is simple – each line contains an IP address, followed by one or more hostnames separated by spaces.
For example, the following line would map the hostname “example.com” to the IP address “192.168.0.100”:
192.168.0.100 example.com
wildcards in /etc/hosts file
You can also use wildcards in your hostname mappings – for instance, the following line would map all subdomains of “example.com” to the same IP address:
192.168.0.100 *.example.com
alias in /etc/hosts file
In addition, you can also use the /etc/hosts file to specify aliases for your hostnames – for example, you could use the following line to alias “localhost” to “my-computer”:
127.0.0.01 my-computer localhost
How to create a new entry in the /etc/hosts file in Linux?
To create a new entry in the /etc/hosts file, you can simply open the file in a text editor vi and add the new information.
For example, if you wanted to add a mapping for the hostname “my-computer”, you would add the following line:127.0.0.01 my-computer
How to delete an entry from the /etc/hosts file in Linux?
To delete an entry from the /etc/hosts file, you can use the following command: sudo vi /etc/hosts
This will open the /etc/hosts file in a text editor, and you can delete the desired entry from the file with dd.
Once you have made your changes, save and close the file with :wq!
What are some common errors that can occur when editing the /etc/hosts file in Linux?
- forgetting to uncomment relevant lines (leading to hostname lookups not working as expected),
- typos (which can cause hostname lookups to fail)
- incorrect formatting (which can also cause issues with hostname lookups).
As you can see, the /etc/hosts file is a powerful file that can be used to control how hostnames are resolved in your Linux environment. If you need to override the results from DNS lookups or create custom hostname aliases, this file is the perfect way to do it! Thanks for reading and feel free to leave any questions or comments below!
Do you want to learn more about Linux? Check out our other blog posts.