Skip to content

Linux-Permission.md

Latest commit

 

History

History
92 lines (64 loc) · 2.26 KB

Linux-Permission.md

File metadata and controls

92 lines (64 loc) · 2.26 KB

File Permissions

In Linux, each file and directory has three types of permissions assigned to it: read, write, and execute. These permissions are represented by characters and determine what actions users and groups can perform on the file.

Permission Representation

  • r: Read permission allows viewing the contents of a file or listing a directory.
  • w: Write permission allows modifying the contents of a file or creating, renaming, or deleting files within a directory.
  • x: Execute permission allows running a file as a program or entering (accessing) a directory.

Symbolic Representation

Permissions are represented in a symbolic notation as follows:

  • -: Indicates a regular file.
  • d: Indicates a directory.
  • r: Read permission.
  • w: Write permission.
  • x: Execute permission.
  • -: Indicates absence of a permission.

Example:

-rw-r--r--

In this example:

  • The owner has read and write permissions (rw-).
  • The group has read permission (r--).
  • Others have read permission (r--).

Changing Permissions

chmod Command

The chmod command is used to change permissions of files and directories.

Syntax:

chmod options permissions filename

Example:

chmod u+x file.txt

This command grants the owner (u) execute (x) permission on file.txt.

Ownership

chown Command

The chown command changes file ownership.

Syntax:

chown owner:group filename

Example:

chown john:developers file.txt

This command changes the owner of file.txt to john and assigns the group developers.

Special Permissions

Set User ID (SUID), Set Group ID (SGID), and Sticky Bit

  • SUID: Executes a file with the permissions of the file owner.
  • SGID: Executes a file with the permissions of the group owner.
  • Sticky Bit: Restricts deletion of files within a directory to only the owner.

Example:

chmod +s file.txt

This command sets the SUID bit on file.txt.

Viewing Permissions

ls Command

The ls command lists files and directories with their permissions.

Example:

ls -l file.txt

This command displays detailed information about file.txt, including permissions.