chmodBefehlszeile

The chmod command, short for change mode, is a fundamental utility in Unix-like operating systems used to modify the file permissions of a specified file or directory. These permissions dictate who can read, write, or execute a file. The command operates on a command-line interface and is essential for system administration and security.

Permissions are typically represented by three sets of characters: user (u), group (g), and others (o). Within each set, the characters r, w, and x denote read, write, and execute permissions, respectively. For example, rwx means read, write, and execute permissions are granted. A hyphen (-) indicates that a permission is denied.

The chmod command can be used in two primary modes: symbolic and octal. In symbolic mode, permissions are modified by adding or removing specific rights for user, group, or others. For instance, chmod u+x file adds execute permission for the user to the file.

In octal mode, permissions are represented by a three-digit number, where each digit corresponds to user, group, and others, and is a sum of the values for read (4), write (2), and execute (1). For example, 755 represents read, write, and execute for the user (4+2+1=7), and read and execute for the group and others (4+1=5).

Understanding and using chmod is crucial for controlling access to files and ensuring the proper functioning and security of a Unix-based system. It allows for fine-grained control over who can interact with files and how.