Linux File Permissions

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*Updated 8/14/2019*

How to Change Directory Permissions in Linux

To change directory permissions in Linux, use the following:

  • chmod +rwx filename to add permissions.
  • chmod -rwx directoryname to remove permissions.
  • chmod +x filename to allow executable permissions.
  • chmod -wx filename to take out write and executable permissions.

Note that “r” is for read, “w” is for write, and “x” is for execute. 

This only changes the permissions for the owner of the file.

touch test file mkdir workfolder
The 4 directory permissions in Linux

 

How to Change Directory Permissions in Linux for the Group Owners and Others

The command for changing directory permissions for group owners is similar, but add a “g” for group or “o” for users:

  • chmod g+w filename
  • chmod g-wx filename
  • chmod o+w filename
  • chmod o-rwx foldername
example of how to change directory permissions in Linux for group owners and others

 

To change directory permissions for everyone, use “u” for users, “g” for group, “o” for others, and “ugo” or “a” (for all).

  • chmod ugo+rwx foldername to give read, write, and execute to everyone.
  • chmod a=r foldername to give only read permission for everyone.

 

How to Change Groups of Files and Directories in Linux

By issuing these commands, you can change groups of files and directories in Linux. 

  • chgrp groupname filename
  • chgrp groupname foldername

Note that the group must exit before you can assign groups to files and directories.

example of changing groups of files and directories

 

How to Change Ownership in Linux

Another helpful command is changing ownerships of files and directories in Linux:

  • chown name filename
  • chown name foldername
example of the chown changing ownership command in Linux

 

These commands will give ownership to someone, but all sub files and directories still belong to the original owner.

You can also combine the group and ownership command by using:

  • chown -R name:filename /home/name/directoryname
example of combining the group and ownership command

 

This command gives someone the ownership of the directory tsfiles, and all files and subfolders. The -R stands for recursive, which transfers ownership of all sub directories to the new owner.

 

How to Change Permissions in Numeric Code in Linux

You may need to know how to change permissions in numeric code in Linux, so to do this you use numbers instead of “r”, “w”, or “x”.

  • 0 = No Permission
  • 1 = Execute
  • 2 = Write
  • 4 = Read

Basically, you add up the numbers depending on the level of permission you want to give.

example of changing permissions in numeric code in Linux

 

Permission numbers are:

  • 0 = ---
  • 1 = --x
  • 2 = -w-
  • 3 = -wx
  • 4 = r-
  • 5 = r-x
  • 6 = rw-
  • 7 = rwx

 

For example:

  • chmod 777 foldername will give read, write, and execute permissions for everyone.
  • chmod 700 foldername will give read, write, and execute permissions for the user only.
  • chmod 327 foldername will give write and execute (3) permission for the user, w (2) for the group, and read, write, and execute for the users.

As you can see, there are several options when it comes to permissions. You have the capability to dictate usability among users. While it may be easier to just give all permission to everyone, it may end up biting you in the end. So choose wisely.

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Contributor

Roman Rafacz

is the product of Western Illinois University’s prestigious academics programs. With a BS in Instructional Technology and a BA in Communications Roman has taken his education and applied it into the vast world of Information Technology. Roman currently works for Jack Morton Worldwide and is a Technical Administrator for the IBM training facility in the Chicago Loop. Roman has been working at Jack Morton for two years and is consistently engulfing himself in different technologies that IBM has to offer. While pursuing higher education through certifications such as A+ and Net + he also enjoys life outside of the computer world with ultimate frisbee, synchronized swimming, and fantasy football.