Скачать с ютуб A solid Introduction to Linux Permissions Part I в хорошем качестве

A solid Introduction to Linux Permissions Part I

In Linux, permissions play a crucial role in controlling access to files and directories. Here are some key points about permissions: Three Permission Types: Permissions in Linux are divided into three types: Read (r): Allows a user to view the contents of a file or list the contents of a directory. Write (w): Allows a user to modify the contents of a file or create, rename, or delete files within a directory. Execute (x): For files, allows a user to execute the file if it is a program or script. For directories, allows a user to enter the directory and access its contents. Three Permission Levels: Permissions are assigned to three levels of users: Owner: The user who owns the file or directory. Group: A set of users who share common permissions. Others: All other users who are not the owner or part of the group. Viewing Permissions: You can view permissions using the ls -l command. The output will display permission information along with other file metadata. Symbolic Representation: Permissions can be represented symbolically using letters r, w, and x, along with dashes . For example, -rwxr-xr- indicates the permissions for a file. Numeric Representation: Permissions can also be represented numerically using a three-digit octal number. Each digit represents the permissions for the owner, group, and others, respectively. The numbers correspond to the sum of the values of read (4), write (2), and execute (1). For example, 755 translates to rwxr-xr-x. Changing Permissions: You can change permissions using the chmod command. You can specify permissions using symbolic or numeric representation. For example: chmod u+x filename adds execute permission for the owner. chmod 755 filename sets permissions to rwxr-xr-x. Changing Ownership: You can change the owner and group of a file using the chown command. For example: chown user:group filename changes the owner and group of the file. Special Permissions: There are also special permissions like the Set User ID (SUID), Set Group ID (SGID), and sticky bit. These are advanced permissions that have specific functions related to security and execution behavior. Understanding and managing permissions effectively is essential for maintaining security and controlling access in a Linux system. -rw-r--r--. 1 stebid stebid 0 Feb 23 10:49 orange In the given permissions -rw-r--r--., here's what each part signifies: First part (-): This indicates the type of file. In this case, it's a regular file. Other possible types include directories (d), symbolic links (l), sockets (s), character devices (c), and block devices (b). Next three parts (rw-, r--, r--): These represent permissions for the owner, group, and others, respectively. rw-: The owner (stebid in this case) has read and write permissions, but no execute permissions. r--: The group (stebid in this case) has read-only permissions, but no write or execute permissions. r--: Others (everyone else) have read-only permissions, but no write or execute permissions. Following .: The period . indicates that there are additional file attributes or ACLs (Access Control Lists) associated with the file. These can provide further control over file access but aren't shown in the standard permission representation. Next part (1): This indicates the number of hard links to the file. Next parts (stebid stebid): These represent the owner and group of the file, respectively. Next part (0): This indicates the size of the file in bytes. Next part (Feb 23 10:49): This shows the timestamp of the last modification of the file. Last part (orange): This is the name of the file. So, summarizing, the given permissions mean that the file named orange is owned by the user stebid and belongs to the group stebid. The owner has read and write permissions, while the group and others have read-only permissions. The file has a size of 0 bytes and was last modified on February 23 at 10:49.