> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Manage File Permissions and Ownership > This article explains how to view and modify file permissions and ownership on a Linux system. In this lesson, we’ll explore how to view and modify file permissions and ownership on a Linux system. You’ll learn to inspect permission bits, change owners and groups, and apply both symbolic and numeric modes with `chmod`, `chown`, and `chgrp`. ## Inspect Current Ownership and Permissions Run `ls -l` to display the owner, group, and permission bits for files and directories: ```bash theme={null} $ ls -l -rw-r----- 1 aaron family 49 Oct 27 14:41 family_dog.jpg ``` * **Owner**: `aaron` * **Group**: `family` * **Permissions**: `-rw-r-----` Only the file owner or the superuser (`root`) can change these settings. ## Viewing and Changing Group Ownership Use `chgrp` to assign a file or directory to a different group you belong to: ```bash theme={null} # Syntax: chgrp $ chgrp wheel family_dog.jpg $ ls -l -rw-r----- 1 aaron wheel 49 Oct 27 14:41 family_dog.jpg ``` Check your group memberships with: ```bash theme={null} $ groups aaron wheel family ``` You can only switch a file’s group to one you’re already a member of. ## Changing File Owner with chown Only `root` can change file owners. Prefix with `sudo` if necessary: ```bash theme={null} # Syntax: sudo chown [:] $ sudo chown jane family_dog.jpg $ ls -l -rw-r----- 1 jane wheel 49 Oct 27 14:41 family_dog.jpg # Change both owner and group in one go: $ sudo chown aaron:family family_dog.jpg $ ls -l -rw-r----- 1 aaron family 49 Oct 27 14:41 family_dog.jpg ``` ## Understanding Permission Bits The permissions string (`-rwxrwxrwx`) breaks down as: * First character: file type * `-` = regular file * `d` = directory * `l` = symbolic link * Next nine: three triplets for **owner**, **group**, and **others**, each with `r` (read), `w` (write), and `x` (execute). ![The image illustrates file and directory permissions in a Unix-like system, showing the permission string "rwxrwxrwx" for owner, group, and others, along with a key explaining the meaning of each permission bit.](https://kodekloud.com/kk-media/image/upload/v1752881384/notes-assets/images/Linux-Professional-Institute-LPIC-1-Exam-101-Manage-File-Permissions-and-Ownership/unix-file-directory-permissions-diagram.jpg) ### Permission Effects * **Files** * `r`: view contents * `w`: modify contents * `x`: execute (scripts or binaries) * **Directories** * `r`: list entries (`ls`) * `w`: create/delete entries * `x`: enter directory (`cd`) ## Modifying Permissions with chmod Use the symbolic syntax: ```bash theme={null} chmod [ugoa][+-=][rwx] ``` | Reference | Meaning | | --------- | --------------------- | | u | owner (user) | | g | group | | o | others | | a | all (u, g, o) | | + | add permissions | | - | remove permissions | | = | set exact permissions | ### Adding Permissions Allow the owner to write: ```bash theme={null} $ ls -l -r--r----- 1 aaron family 49 Oct 27 14:41 family_dog.jpg $ chmod u+w family_dog.jpg $ ls -l -rw-r----- 1 aaron family 49 Oct 27 14:41 family_dog.jpg ``` ### Removing Permissions Remove the read bit for others: ```bash theme={null} $ chmod o-r family_dog.jpg $ ls -l -rw-r----- 1 aaron family 49 Oct 27 14:41 family_dog.jpg ``` ![The image shows a guide on removing permissions in a command-line interface, with examples for users, groups, and others. It includes options like u-, g-, and o- with examples such as u-w, g-rw, and o-rwx.](https://kodekloud.com/kk-media/image/upload/v1752881385/notes-assets/images/Linux-Professional-Institute-LPIC-1-Exam-101-Manage-File-Permissions-and-Ownership/remove-permissions-command-line-guide.jpg) ### Setting Exact Permissions Grant group read-only: ```bash theme={null} $ chmod g=r family_dog.jpg $ ls -l -rw-r----- 1 aaron family 49 Oct 27 14:41 family_dog.jpg $ chmod g=rw family_dog.jpg $ ls -l -rw-rw---- 1 aaron family 49 Oct 27 14:41 family_dog.jpg ``` ### Combining References You can comma-separate multiple adjustments: ```bash theme={null} $ ls -l -rw-r--r-- 1 appuser appuser 49 Oct 27 14:41 family.jpg # Owner read/write, group read, others none $ chmod u=rw,g=r,o= family.jpg $ ls -l -rw-r----- 1 appuser appuser 49 Oct 27 14:41 family.jpg # Mix add/remove in one command $ chmod u+rw,g-w family_dog.jpg ``` ## Numeric (Octal) Notation To inspect the octal value, use `stat`: ```bash theme={null} $ stat family_dog.jpg Access: (0640/-rw-r-----) Uid: ( 1000/aaron) Gid: ( 10/family) ``` Here **owner** has `rw-` (6), **group** has `r--` (4), **others** have `---` (0) → mode `640`. ![The image illustrates octal file permissions, showing the conversion between symbolic, binary, and decimal representations. It includes examples of permissions like "rw-r--r--" and "rwxr-xr-x" with their corresponding binary and decimal values.](https://kodekloud.com/kk-media/image/upload/v1752881386/notes-assets/images/Linux-Professional-Institute-LPIC-1-Exam-101-Manage-File-Permissions-and-Ownership/octal-file-permissions-symbolic-binary.jpg) Alternatively, assign values: `r=4`, `w=2`, `x=1`: * `rwx` = 4+2+1 = 7 * `r-x` = 4+0+1 = 5 * `r--` = 4+0+0 = 4 ![The image explains octal permissions in a Unix-like system, showing how the permissions "rw-r-----" translate to the octal value "640". It also provides a key for permission values: read (r) is 4, write (w) is 2, and execute (x) is 1.](https://kodekloud.com/kk-media/image/upload/v1752881386/notes-assets/images/Linux-Professional-Institute-LPIC-1-Exam-101-Manage-File-Permissions-and-Ownership/octal-permissions-unix-diagram-640.jpg) ### Setting Numeric Permissions ```bash theme={null} $ chmod 755 family_dog.jpg # rwxr-xr-x $ chmod 640 family_dog.jpg # rw-r----- ``` ## Further Reading * [Linux File Permissions – Official Documentation](https://www.kernel.org/doc/html/latest/filesystems/permissions.html) * [chmod Command Tutorial](https://linux.die.net/man/1/chmod) * [chown and chgrp Usage](https://linux.die.net/man/1/chown)