The chown (Change Owner) command in Linux is used to change the owner and group ownership of files and directories. It is particularly useful when managing permissions for multiple users on a system.

Every file in Linux has an owner and a group, as seen in the ls -l output:

-rw-r--r-- 1 user1 group1 1234 Jan 30 12:00 file.txt

• user1 → Owner
• group1 → Group

Now, let’s explore 10 powerful chown commands with practical explanations.

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1. Change the Owner of a File

chown newuser file.txt

What it does:

• Changes the owner of file.txt to newuser.
• The group remains unchanged.

Example Before (ls -l file.txt):

-rw-r--r-- 1 olduser group1 1234 Jan 30 12:00 file.txt

Example After:

-rw-r--r-- 1 newuser group1 1234 Jan 30 12:00 file.txt

Useful when transferring file ownership to another user.

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2. Change the Owner and Group of a File

chown newuser:newgroup file.txt

What it does:

• Changes owner to newuser and group to newgroup.

Before:

-rw-r--r-- 1 olduser oldgroup file.txt

After:

-rw-r--r-- 1 newuser newgroup file.txt

Ensures both owner and group are modified in one command.

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3. Change Only the Group of a File

chown :newgroup file.txt

What it does:

• The owner remains unchanged, but the group is changed.

Before:

-rw-r--r-- 1 user1 oldgroup file.txt

After:

-rw-r--r-- 1 user1 newgroup file.txt

Equivalent to the chgrp command.

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4. Change Owner and Group for Multiple Files

chown newuser:newgroup file1.txt file2.txt

What it does:

• Modifies both file1.txt and file2.txt.

Before:

-rw-r--r-- 1 user1 group1 file1.txt
-rw-r--r-- 1 user1 group1 file2.txt

After:

-rw-r--r-- 1 newuser newgroup file1.txt
-rw-r--r-- 1 newuser newgroup file2.txt

Saves time when modifying multiple files at once.

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5. Change Owner for a Directory and Its Contents

chown -R newuser:newgroup mydir/

What it does:

• -R → Applies changes recursively to all files and subdirectories in mydir/.

Before:

drwxr-xr-x 1 user1 group1 mydir/
-rw-r--r-- 1 user1 group1 file1.txt
-rw-r--r-- 1 user1 group1 file2.txt

After:

drwxr-xr-x 1 newuser newgroup mydir/
-rw-r--r-- 1 newuser newgroup file1.txt
-rw-r--r-- 1 newuser newgroup file2.txt

Useful when transferring ownership of a project directory.

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6. Change Ownership Based on Another File’s Ownership

chown --reference=referencefile targetfile

What it does:

• Sets targetfile ownership to match referencefile.

Example:

chown --reference=existing.txt newfile.txt

• newfile.txt gets the same owner and group as existing.txt.

Quick way to match file ownership settings!

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7. Change Ownership Using User ID (UID) and Group ID (GID)

chown 1001:1002 file.txt

What it does:

• 1001 → User ID (UID)
• 1002 → Group ID (GID)

Before:

-rw-r--r-- 1 user1 group1 file.txt

After (ls -n file.txt to check UIDs/GIDs):

-rw-r--r-- 1 1001 1002 file.txt

Helpful in scripts where UID/GID is known but not the username/group name.

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8. Change Ownership for Files Owned by a Specific User

chown newuser:newgroup $(find /path -user olduser)

What it does:

• Finds all files owned by olduser and transfers them to newuser:newgroup.

Example: Change all files owned by john under /home/projects:

chown newuser:newgroup $(find /home/projects -user john)

Useful when deleting a user and reassigning files.

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9. Prevent Symbolic Link Issues with -h

chown -h newuser:newgroup symlink

What it does:

• Changes the owner of a symbolic link, not the target file.

Without -h (ls -l symlink output):

lrwxrwxrwx 1 olduser oldgroup symlink -> targetfile

After using -h:

lrwxrwxrwx 1 newuser newgroup symlink -> targetfile

Useful when dealing with symbolic links in /etc or /usr/local/bin/.

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10. Restrict Ownership Transfer to Superuser Only

chown root file.txt

What it does:

• Transfers file ownership to root.
• Can only be executed by a superuser (root).

Before:

-rw-r--r-- 1 user1 group1 file.txt

After (ls -l output):

-rw-r--r-- 1 root group1 file.txt

Important for securing critical system files.

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Final Thoughts

• chown is essential for managing file ownership and permissions.
• Always use -R carefully, especially on /etc/, /home/, or /var/ directories.
• Changing ownership to root can restrict user access.