Chgen

Chgen is a command-line utility commonly found on Unix-like operating systems. Its primary function is to change the mode of files, which refers to the permissions granted to different user categories. These categories typically include the owner of the file, the group associated with the file, and others (everyone else).

The command allows users to modify read, write, and execute permissions. For instance, a user might use chgen to grant read and write access to the owner while restricting access for others. Permissions can be set numerically using octal notation, where each digit represents the permissions for the owner, group, and others respectively, with values 4 for read, 2 for write, and 1 for execute. Alternatively, symbolic notation can be used, which involves specifying the user category (u for user, g for group, o for others, a for all), an operator (+ to add, - to remove, = to set precisely), and the permission(s) (r for read, w for write, x for execute).

Chgen is a fundamental tool for system administration and file management, enabling control over who can access and modify files and directories. It plays a crucial role in maintaining system security and data integrity by enforcing access control policies. Its usage is widespread across various Linux distributions and other Unix-based operating systems.