Linux change owner recursive

How To Change Ownership of Files and Directories in Unix

I’ve just been asked a question about changing the ownership of files from one Unix user to another, and thought it probably makes sense to have a quick post on it.

File ownership in Unix

Just to give you a quick reminder, I’d like to confirm that every single file in Unix belongs to some user and some group. There simply isn’t a way to create a file without assigning ownership. I’ve briefly touched the topic of confirming file ownership in Unix before, so today I will simply build on that and show you how to change ownership of files.

Here’s a setup for today: I have created a temporary directory with a few files and made myself the owner of all the files:

As you can see from this listing, the owner (third field in each line) is my username – greys. The next field is a Unix group of each file’s owner – admin in my example.

Changing owner of a file in Unix

Changing file ownership means only updating the association between a Unix user and a file, and nothing else. When you’re changing the owner of a file, no data contained in a file is changed.

To change the owner of a file, you need to use the chown command (easy enough to remember: CHange OWNer – chown), with the following syntax:

In this command, nobody is the username of the new owner for a list of files. In my example, the only file we’d like to change ownership for is file1.

It is important to realize that you can only change file ownership as a super-user (root). Any regular Unix user cannot change the ownership of any file, and I’d like to explain why.

Indeed, some people are surprised: if I’m the owner of a given file, why can’t I change the ownership for it? That’s because transferring the ownership will mean some other Unix user will become the owner of the file(s) in question. So changing ownership is like making a decision not only for yourself, but for the new owner of the files.This is only something a super-user – special administrative account in Unix – can do.

The same logic applies to other people not being able to become owners of your files, even if they’re willing to assume the new responsibilities of owning files. They cannot revoke your ownership, because each Unix user is only allowed to make decisions and take actions on his/her own behalf.

That’s why you will probably see an error like this if you attempt to change ownership of a file as your own regular Unix user:

But if we become root:

… we’ll have no problem changing owners for any files:

Changing owner for multiple files

If you’re going to change owner of a few files, this can easily be done using either a full list of files or a mask.

First, here’s an example of updating ownership for a specified list of files (and as you can see, directories as well):

IMPORTANT: here’s one thing which is often forgotten: when you’re changing an owner of a directory, this DOES NOT automatically change owner of all the files which already exist in this directory. So, if we check the file3 in dir1 after the example above, we can see that even though dir1 now belongs to user nobody, file3 in it still belongs to me:

If your intention is to change ownership of all the files and directories of a certain location in your filesystem, you need to use a -R option of the chown command, which means recursive ownership change:

And just to further demonstrate this, I’m going to change owner of all the files and directories in /home/greys/example directory back to my own username, greys:

Changing group ownership for a file

Similar to the chown command, there’s a command specifically helping you with changing not the owner (user) of a file.

IMPORANT: unlike chown command, chgrp can be used by non-privileged (regular) users of a system. So you don’t have to be root if you want to change a group ownership for some of your files, provided that you’re changing the ownership to a group you’re a member of.

For example, I’m a member of quite a few groups on one of my Ubuntu servers:

Now, if I create a new file, it will by default belong to my primary group (called greys, just like my username):

I can now change group ownership of this file, in this case to a group admin, which I’m also part of.

and this is just to confirm that the change actualyl happened:

That’s it for today, good luck with changing file owners on your Unix system!

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chown(1) — Linux man page

Synopsis

Description

Options

Change the owner and/or group of each FILE to OWNER and/or GROUP. With —reference, change the owner and group of each FILE to those of RFILE. -c, —changes like verbose but report only when a change is made —dereference affect the referent of each symbolic link (this is the default), rather than the symbolic link itself -h, —no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the ownership of a symlink) —from=CURRENT_OWNER:CURRENT_GROUP change the owner and/or group of each file only if its current owner and/or group match those specified here. Either may be omitted, in which case a match is not required for the omitted attribute. —no-preserve-root do not treat ‘/’ specially (the default) —preserve-root fail to operate recursively on ‘/’ -f, —silent, —quiet suppress most error messages —reference=RFILE use RFILE’s owner and group rather than specifying OWNER:GROUP values -R, —recursive operate on files and directories recursively -v, —verbose output a diagnostic for every file processed

The following options modify how a hierarchy is traversed when the -R option is also specified. If more than one is specified, only the final one takes effect. -H if a command line argument is a symbolic link to a directory, traverse it -L traverse every symbolic link to a directory encountered -P do not traverse any symbolic links (default) —help display this help and exit —version output version information and exit

Owner is unchanged if missing. Group is unchanged if missing, but changed to login group if implied by a ‘:’ following a symbolic OWNER. OWNER and GROUP may be numeric as well as symbolic.

Examples

Author

Reporting Bugs

Copyright

See Also

The full documentation for chown is maintained as a Texinfo manual. If the info and chown programs are properly installed at your site, the command info coreutils aqchown invocationaq

should give you access to the complete manual.

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Chown Command: Change Owner of File in Linux

Home » SysAdmin » Chown Command: Change Owner of File in Linux

The chown command changes user ownership of a file, directory, or link in Linux. Every file is associated with an owning user or group. It is critical to configure file and folder permissions properly.

In this tutorial, learn how to use the Linux chown command with examples provided.

• Linux or UNIX-like system
• Access to a terminal/command line
• A user with sudo privileges to change the ownership. Remember to run the commands with sudo to execute them properly.

Linux Chown Command Syntax

The basic chown command syntax consists of a few segments. The help file shows the following format:

• [OPTIONS] – the command can be used with or without additional options.
• [USER] – the username or the numeric user ID of the new owner of a file.
• [:] – use the colon when changing a group of a file.
• [GROUP] – changing the group ownership of a file is optional.
• FILE – the target file.

Superuser permissions are necessary to execute the chown command.

In this guide, we tested the command examples with the chown version 8.28 in Ubuntu 18.04.2 LTS.

To check the chown version on your machine, enter:

The output will look similar to this:

How to Check Ownership of a File in Linux

First, you need to know the original file owner or group before making ownership changes using the chown command.

To check the group or ownership of Linux files and directories in the current location, run the following command:

An example output of the ls command looks like this:

How to Change the Owner of a File

Changing the owner of a file with chown requires you to specify the new owner and the file. The format of the command is:

The following command changes the ownership of a file sample from root to the user test:

Use the same format to change the ownership for both files and directories.

Change the Owner of a File With UID

Instead of a username, you can specify a user ID to change the ownership of a file.

Make sure there is no user with the same name as the numeric UID. If there is, the chown command gives priority to the username, not the UID.

Note: To check a user’s ID, run id -u USERNAME from the terminal.

Change Ownership of Multiple Linux Files

List the target file names after the new user to change the ownership for multiple files. Use single spaces between the file names.

In the following example, root will be the new owner of files sample2 and sample3.

Combine file names and directory names to change their ownership with one command. For example:

Do not forget that the commands are case sensitive.

How to Change the Group of a File

With chown, you can change a group for a file or directory without changing the owning user. The result is the same as using the chgrp command.

Run the chown command using the colon and a group name:

The following example changes the group of the file sample3 from grouptest to group3.

List multiple names of files or directories to make bulk changes.

Change the Group of a File Using GID

Similar to UID, use a group ID (GID) instead of a group name to change the group of a file.

Change Owner and the Group

To assign a new owner of a file and change its group at the same time, run the chown command in this format:

Therefore, to set linuxuser as the new owner and group2 as the new group of the file sample2:

Remember that there are no spaces before or after the colon.

Change Group to a Users Login Group

The chown command assigns the owner’s login group to the file when no group is specified.

To do so, define a new user followed by a colon, space, and the target file:

The following example changes the group ownership to the login group of linuxuser:

Transfer Ownership and Group Settings from One File to Another

Rather than changing the ownership to a specific user, you can use the owner and a group of a reference file.

Add the —reference option to the chown command to copy the settings from one file to another:

Remember to type in the names of the files correctly to avoid the error message:

Check Owner and Group Before Making Changes

The chown command —from option lets you verify the current owner and group and then apply changes.

The chown syntax for checking both the user and group looks like this:

The example below shows we first verified the ownership and the group of the file sample3:

Then chown changed the owner to linuxuser and the group to group3.

Check Owner Only

The option —from can be used to validate only the current user of a file.

Check Group Only

Similar to the previous section, you can validate only the group of a file using the option —from .

Here is an example where we verified the current group before changing it:

Remember to use the colon for both group names to avoid error messages.

How to Recursively Change File Ownership

The chown command allows changing the ownership of all files and subdirectories within a specified directory. Add the -R option to the command to do so:

In the following example, we will recursively change the owner and the group for all files and directories in Dir1.

Chown Command and Symbolic Links

To change the owner of a symbolic link, use the -h option. Otherwise, the ownership of the linked file will be changed.

The following image shows how symbolic links behave when -h is omitted.

The owner and group of the symbolic link remain intact. Instead, the owner and the group of the file textfile changed.

To push the changes to the link, run the chown command with the -h flag:

In the following example, we changed the owner and group of a symbolic link.

Display Chown Command Process Details

By default, the terminal does not display the chown process information. To see what happens under the hood, use one of the two command line flags:

• The option –v produces the process details even when the ownership stays the same.
• The option –c displays the output information only when an owner or group of the target file changes.

For example, if we specify the current owner as a new owner of the file:

The terminal produces the following output:

Switch from -v to -c and there will be no messages in this case. This happens because there are no owner or group changes.

The information is particularly useful with the recursive chown command:

In this example, the output lists all objects affected after running the command.

Suppress Chown Command Errors

To avoid seeing potential error messages when running the chown command, use the -f option:

The example below shows the error message for a non-existent file or directory:

Adding the -f flag suppresses most error messages. However, if you specify an invalid username, the error message appears:

Now you know how to use chown command in Linux to change a file’s user and/or group ownership.

Take extra caution when changing the group or ownership of a file or directories.

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