What is SGID bit or special permission in Linux?

In this article, you will learn about what is SGID permission in Linux and How to use it?

SGID stands for Set Group IDentification. We use SGID to give special permission in the group section of the permission. You can also read first about What is SUID bit or special permission in Linux?

We have a system admin group, or we have certain sales user groups or any other department, and we want to give any special permission for a file. In this case, we can use the SGID permission.

To understand this concept, I’m going to create a file with the name amit. Below you can see that file with permission.

We can break the above permission for understanding like below,

- (this indicate the file)

rw- (this for user)

r-x (this is for the group)

r– (this for other)

There is two difference i.e. small s and capital S.

rwx +s = rws (Small s means, the user has both execute and special permission)

rw- +s = rwS (Capital S means, the user has only special permission)

As we know that this SGID permission works on the group, here the group name is sahil and permission for the group is rw-.

Now I’m giving special permission to file amit.

The symbolic mode

chmod g+s amit

here, g represents the group and s for special permission.

amit is the file name, you can change it with your file name, after pressing enter to apply for the permission, Capital S represents that it has only special permission. As a result, you can look like the below picture.

sgid permission in Linux

Absolute mode or Numerical or Octal method

You can also give permission to use the octal method,

In the octal method, SGID is represented by number two (2). So the command will be.

chmod 2664 amit

How to find all the SGID permission set file in Linux

find / -perm /2000

Here, I am looking for SGID set files in / (root partition or root directory). If you are looking to another place, then change the / with your specific location.

Conclusion

In this tutorial, you learned about SGID permission in Linux. It is special permission. We don’t generally need it, but you must know it. I hope you understand, but if you have any questions, you can ask in the comment section.

Also, you can further read,

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