SUID Permissions in Linux: What They Are and How to Use Them

SUID Permissions in Linux: What They Are and How to Use Them

Do you know what SUID permissions are, or how to use them in Linux? If not, you aren’t alone! This article will give you all the information you need to understand SUID permissions and how to use them in your everyday Linux usage.

 What are SUID permissions

In Linux, every file has an owner and a group associated with it. These permissions dictate who can read, write, or execute the file. But what about when you need a specific file to be executed with root privileges? This is where SUID permissions come into play. Whenever a program runs, it gets its own process ID number which gives it an ID that distinguishes itself from other processes.

When you have set the SUID permission on a file, anyone running that program automatically has their user ID changed to the owner of that file (which means they have full permissions). You should only use this permission on files which require elevated privileges for executing them; do not give this permission out lightly because any person who can access your system could potentially become root just by running your executable!

 How do I set them

When a file has the SUID permission set, that means that the file will be executed with the permissions of the owner of the file, rather than the permissions of the user who is running it. This can be useful for executables that need to access files or perform actions that are outside the scope of the user’s permissions.

In order to set SUID permissions, you use the chmod command with the u+s option. For example, if you wanted to give all users permission to run the locate command, you would use the following command: sudo chmod u+s /usr/bin/locate. To remove the SUID permission from a file, you would use this command:

sudo chmod -s /usr/bin/locate . Remember, if you change the permissions on a file and want to grant certain users extra privileges without granting those privileges to everyone else, use umask in addition to these commands. Umask is a system call which determines how much of the permissions you want to deny other users. If your umask were 002, then other users would only have read and write privileges by default unless they had been granted more rights by using chmod or umask.

 Common uses of SUID permissions

There are a few common use cases for SUID permissions in Linux. One is to allow non-root users to run binaries that perform actions that require elevated privileges, like changing the system time. Another is to give users access to devices or files that they wouldn’t normally have access to.

Finally, SUID permissions can be used as a security measure to prevent malicious code from running with elevated privileges. For example, if you wanted to execute a binary but didn’t want it executing under root privileges, you could make it SUID so that only an executable file owned by root would be able to execute it.

When should I use them

When you need to give a specific user or group of users the ability to run a program with elevated privileges, you can use SUID permissions. This allows them to perform actions that could potentially affect the entire system. However, this also means that you need to be careful about which programs you grant these permissions to. In general, only programs that absolutely need them should have SUID permissions.

For example, if you’re setting up a login shell for your regular user account on a shared server, then it would make sense to add the su command as SUID. On the other hand, if you’re adding su as SUID for an account that is meant for public access (like an administrative account), then there are many potential security implications and it’s best not to do so.


When you’re working with files and permissions in Linux, you may come across the SUID permission. SUID stands for set user ID and it’s a special type of file permission that allows a user to run a program with the permissions of the owner of that program. This can be useful in some cases, but it also presents a security risk. In this article, we’ll explain what SUID permissions are and how to use them safely. We’ll also show an example of when they might be used.

For example, when you create a script that needs to be executed by another user (such as your boss), the SUID permission can make sure that only the appropriate user has access to it.

Keep in mind, though, that if somebody else finds out about your script and knows its name or where it is stored on your computer, they could run it themselves with any necessary permissions – so make sure not to share your scripts unless you want anybody else who finds them to have access! Also note that many programs installed through package managers like APT and YUM will automatically turn on the SUID permission without telling you; if there’s something you don’t understand about why it was done, consult the package manager documentation for details.

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