What is linux root access
root is the user name or account that by default has access to all commands and files on a Linux or other Unix-like operating system. It is also referred to as the root account, root user and the superuser.
The word root also has several additional, related meanings when used as part of other terms, and thus it can be a source of confusion to people new to Unix-like systems.
One of these is the root directory, which is the top level directory on a system. That is, it is the directory in which all other directories, including their subdirectories, and files reside. The root directory is designated by a forward slash ( / ).
Another is /root (pronounced slash root), which is the root user’s home directory. A home directory is the primary repository of a user’s files, including that user’s configuration files, and it is usually the directory in which a user finds itself when it logs into a system. /root is a subdirectory of the root directory, as indicated by the forward slash that begins its name, and should not to be confused with that directory. Home directories for users other than root are by default created in the /home directory, which is another standard subdirectory of the root directory.
Root privileges are the powers that the root account has on the system. The root account is the most privileged on the system and has absolute power over it (i.e., complete access to all files and commands). Among root’s powers are the ability to modify the system in any way desired and to grant and revoke access permissions (i.e., the ability to read, modify and execute specific files and directories) for other users, including any of those that are by default reserved for root.
A rootkit is a set of software tools secretly installed by an intruder into a computer that allows such intruder to use that computer for its own, usually nefarious, purposes when desired. Well designed rootkits are able to obtain root access (i.e., access to the root account rather than just to a user account) and to hide most or all traces of their presence and activities.
The use of the term root for the all-powerful administrative user may have arisen from the fact that root is the only account having write permissions (i.e., permission to modify files) in the root directory. The root directory, in turn, takes its name from the fact that the filesystems (i.e., the entire hierarchy of directories that is used to organize files) in Unix-like operating systems have been designed with a tree-like (although inverted) structure in which all directories branch off from a single directory that is analogous to the root of a tree.
The original UNIX operating system, on which Linux and other Unix-like systems are based, was designed from the very beginning as a multi-user system because personal computers did not yet exist and each user was connected to the mainframe computer (i.e., a large, centralized computer) via a dumb (i.e., very simple) terminal. Thus it was necessary to have a mechanism for separating and protecting the files of the individual users while allowing them to use the system simultaneously. It was also necessary to have a means for enabling a system administrator to perform such tasks as entering user directories and files to correct individual problems, granting and revoking powers for ordinary users, and accessing critical system files to repair or upgrade the system.
Every user account is automatically assigned an identification number, the UID (i.e., user ID), by a Unix-like system, and the system uses these numbers instead of the user names to identify and keep track of the users. Root always has a UID of zero. This can be verified by logging in as root (if using a home computer or other system that permits this operation) and running the echo command to display the UID of the current user, i.e.,
echo is used to repeat on the screen what is typed in after it. The dollar sign preceding UID tells echo to display its value rather than its name.
The UID for root (as well as for all other users) can also be seen by looking at /etc/passwd, which is the configuration file for user data. This file can be viewed (by default by all users) by using the cat command (which is commonly employed to read files), i.e.,
The output of cat /etc/passwd in this example is piped (i.e., transferred) to the less command to allow it to be read one screenful at a time, which is useful if the file is a long one. The line of output for root will look something like root:x:0:0:root:/root:/bin/bash. The first column shows the user name and the third column shows the UID, which can be seen to be zero.
The permissions system in Unix-like operating systems is set by default to prevent access by ordinary users to critical parts of the system and to files and directories belonging to other users. Thus, it can be very tempting for users new to such systems, especially those who are accustomed to systems with a weak permissions system or without any permissions system (e.g., Microsoft Windows or the older versions of the Macintosh), to bypass this permissions system on their personal computers by logging directly into the root account and staying there. Although this provides momentary relief, it should be avoided and ordinary work on the system should be done via an ordinary user account.
This is because it is very easy to damage a Unix-like system when using it as root — much easier than to damage most other types of operating systems. The designers of most other operating systems devised methods of protecting the system and data to compensate for the lack of a robust permissions system.
However, an important principle of Unix-like operating systems is the provision of maximum flexibility to configure the system, and thus the root user is fully empowered. Unix-like systems assume that the system administrator knows exactly what he or she is doing and that only such individual(s) will be using the root account. Thus, there is virtually no safety net for the root user in the event of a careless error, such as damaging or deleting a critical system file (which could make the entire system inoperable).
Adding to the danger of routinely using the system as root is the fact that all processes (i.e., instances of programs in execution) started by the root user have root privileges. Because even the most widely used and well-tested application programs contain numerous programming errors (due to the huge amount of code required and its great complexity), a skilled attacker can often find and exploit such an error to obtain control of a system when a program is run with root privileges rather than using an ordinary user account, with its very limited privileges.
A critical means for preventing users from directly damaging Unix-like systems or increasing the vulnerability of such systems to damage by others is the avoidance of using the root account except when absolutely necessary, even by knowledgeable and experienced system administrators. That is, rather than routinely logging into the system as root, administrators should log in with their ordinary user accounts and then use commands, such as su, kdesu and sudo, that provide them with root privileges only as needed and without requiring a new login.
For example, to become root with su merely requires typing
at the command line (i.e., in the all-text mode), pressing the Enter key and supplying the root password. The account of the previous user can be returned to by pressing the Ctrl and d keys simultaneously or by typing the word exit and then pressing the Enter key.
The security associated with using su can be increased by using its -c option, which terminates it and causes an immediate return to the former user account after the current command has completed execution or after any program that it has launched has been closed.
Tasks that require root privileges include moving files or directories into or out of system directories (i.e., directories that are critical to the functioning of the operating system), copying files into system directories, granting or revoking user privileges, some system repairs, and the installation of some application programs. By default, it is not necessary to be root to be able to read most configuration files and documentation files in system directories, although it is necessary to be root to modify them.
Root privileges are usually required for installing software in RPM (Red Hat Package Manager) package format because of the need to write to system directories. If an application program is being compiled (i.e., converted into runnable form) from source code (i.e., its original, human-readable form), however, it can usually be configured to install and run from a user’s home directory. Root privileges are not needed by an ordinary user to compile and install software in its home directory. Compiling software as root should be avoided for security reasons.
On large systems used by businesses and other organizations, there will likely be several system administrators. Each will have its own account in which it will ordinarily work (and the activities of which will be automatically recorded in system logs for security and repair purposes) but will also have access to the root account for use when necessary. The system administrator(s) might grant limited root privileges to some individuals, such as assistant administrators.
Created May 29, 2005. Updated October 27, 2007.
Copyright © 2005 — 2007 The Linux Information Project. All Rights Reserved.
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Root User in Ubuntu- Important Things You Should Know
Last updated October 23, 2020 By Abhishek Prakash 28 Comments
How do you become root user in Ubuntu?
Either you run commands with root privilege like this:
Or you switch user in Ubuntu to root user like this:
In both cases, you’ll have to enter your own user account’s password. But there’s more to root account in Ubuntu that you should know.
When you have just started using Linux, you’ll find many things that are different from Windows. One of those ‘different things’ is the concept of the root user.
In this beginner series, I’ll explain a few important things about the root user in Ubuntu.
Please keep in mind that while I am writing this from Ubuntu user’s perspective, it should be valid for most Linux distributions.
You’ll learn the following in this article:
What is root user? Why is it locked in Ubuntu?
In Linux, there is always a super user called root. This is the super admin account that can do anything and everything with the system. It can access any file and run any command on your Linux system.
With great power comes great responsibility. Root user gives you complete power over the system and hence it should be used with great cautious. Root user can access system files and run commands to make changes to the system configuration. And hence, an incorrect command may destroy the system.
This is why Ubuntu and other Ubuntu-based distributions lock the root user by default to save you from accidental disasters.
You don’t need to have root privilege for your daily tasks like moving file in your home directory, downloading files from internet, creating documents etc.
Take this analogy for understanding it better. If you have to cut a fruit, you use a kitchen knife. If you have to cut down a tree, you have to use a saw. Now, you may use the saw to cut fruits but that’s not wise, is it?
Does this mean that you cannot be root in Ubuntu or use the system with root privileges? No, you can still have root access with the help of ‘sudo’ (explained in the next section).
Bottom line:
Root user is too powerful to be used for regular tasks. This is why it is not recommended to use root all the time. You can still run specific commands with root.
How to run commands as root user in Ubuntu?
You’ll need root privileges for some system specific tasks. For example, if you want to update Ubuntu via command line, you cannot run the command as a regular user. It will give you permission denied error.
So, how do you run commands as root? The simple answer is to add sudo before the commands that require to be run as root.
Ubuntu and many other Linux distributions use a special mechanism called sudo. Sudo is a program that controls access to running commands as root (or other users).
Sudo is actually quite a versatile tool. It can be configured to allow a user to run all commands as root. You may configure it run only a selected few commands as root. You can also configure to run sudo without password. It’s an extensive topic and maybe I’ll discuss it in details in another article.
For the moment, you should know that when you install Ubuntu, you are forced to create a user account. This user account works as the admin on your system and as per the default sudo policy in Ubuntu, it can run any command on your system with root privileges.
The thing with sudo is that running sudo doesn’t require root password but the user’s own password.
And this is why when you run a command with sudo, it asks for the password of the user who is running the sudo command:
As you can see in the example above, user abhishek was trying to run the ‘apt update’ command with sudo and the system asked the password for abhishek.
If you are absolutely new to Linux, you might be surprised that when you start typing your password in the terminal, nothing happens on the screen. This is perfectly normal because as the default security feature, nothing is displayed on the screen. Not even the asterisks (*). You type your password and press enter.
Bottom line:
To run commands as root in Ubuntu, add sudo before the command.
When asked for password, enter your account’s password.
When you type the password on the screen, nothing is visible. Just keep on typing the password and press enter.
How to become root user in Ubuntu?
You can use sudo to run the commands as root. However, in situations, where you have to run several commands as root and you keep forgetting to add sudo before the commands, you may switch to root user temporarily.
The sudo command allows you to simulate a root login shell with this command:
You’ll notice that when you switch to root, the shell command prompt changes from $ (dollar key sign) to # (pound key sign). This makes me crack a (lame) joke that pound is stronger than dollar.
Though I have showed you how to become the root user, I must warn you that you should avoid using the system as root. It’s discouraged for a reason after all.
You can use su command to switch users in Ubuntu. You can use it with sudo to temporarly switch to root user:
If you try to use the su command without sudo, you’ll encounter ‘su authentication failure’ error.
You can go back to being the normal user by using the exit command.
How to enable root user in Ubuntu?
By now you know that the root user is locked by default in Ubuntu based distributions.
Linux gives you the freedom to do whatever you want with your system. Unlocking the root user is one of those freedoms.
If, for some reasons, you decided to enable the root user, you can do so by setting up a password for it:
Again, this is not recommended and I won’t encourage you to do that on your desktop. If you forgot it, you won’t be able to change the root password in Ubuntu again.
You can lock the root user again by removing the password:
In the end…
I hope you have a slightly better understanding of the root concept now. If you still have some confusion and questions about it, please let me know in the comments. I’ll try to answer your questions and might update the article as well.
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