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Users And Groups Linux Permissions

User Group And Id Number:

Linux operating system uses different users and groups to define the processing like file creation changing file permission etc. The id number of group and user are maintained into Linux system in the form of UID and GID.

/ETC/Password And Shadow:

Linux operating system uses a directory to manage the files and separate with / slash symbol. It uses a directory to manage different type of processing and configuration.

1. /Etc/Password:

It is a file that contains the user details like username, password, user Id, group Id, user directory, shall information of the user. We can display the user details with this file.

2. /Etc/Shadow:

It is a file that contains the details of a password into an extended format. It manages the files for the password like password expiry date, creation date etc. This file is reliable by all users. It is possible for any user to get the encrypted password of any other user on the system.

3. /etc/group:

It is a file that maintains the group details like group name, group Id, group permissions, list of groups with, separator.

4. /etc/gshadow:

Linux operating system also maintains the group password details in the encrypted format. G shadow file maintains the details of group password.

User Management Tools:

Linux operating system allows us graphical icons to manage the user and its related configuration means to create, alter, modify the user account. In this, we maintain username, password, login shell etc for creating a new group.

1. User add:

It is a command that allows creating new user into the system and can log in the application for processing. In this, we pass username for the new user.

-d: It is used to create a directory for a user.

-g: To define the group for existing user.

-s: It is used to set the default shell for the user.

2. User mod:

It is a command that allows altering the user details like username, user directory, user shell etc. We use all same option of user add.

3. User del:

It is a command that allows deleting the existing user.

-r: It is used to delete the user directory and all files.

Example:

user add anna↵

password kanna↵

user add anna -d/user↵

user mod anna-d/xy↵

user del anna

user del-r anna.

4. Group add:

It is a command that creates new group into the system in this we pass group name

System User And Group:

The system creates the user account for managing the files and directories. The system assigns the group and user Id to identify them. The Id number is between 1-499. The superuser root process the instructions as administrator.

Monitoring Login:

Login is the process to check the authorized user and provide required files and data for processing Linux system allow us a command to display the list of users using W. we can display the list and processing of running logs of users. The command can display the connection and reboot history. It means to display the list of logged user and most recently system get the reboot. We can also read the list of bad user try to login the system.

Special Permission For Executable:

The permissions are defined in the form of group user and others, The groups are identified as the list of users and owner identified a user of the particular file. Linux system allows us a special permission to manage the executable files. The system maintains the SUID to set the user identification number and SGID for group identification number. A command chmod is used to change the permission of a particular file or directory Linux system provide GUI tools to set the special permission of executable file or directory.

1. SUID Permission:

This permission is set for the executable file, it means that the command will run with the authority of the owner of the file rather than the authority of the user running the command. It is basically used to define the particular permission on particular command for execution.

2. SGID Permission:

Command that running with the SGID permission for particular group. The system assigns the permission for group and set of users the special commands are assigned, group. The list of users can execute the functions and command which are defined on that group.

Special Permission For Directory:

explaination of permission of group in linux
image source:-http://www.firewall.cx

The sticky bit for a directory sets special re-direction on deletion of files. The permission can also assign on the directory and changed with chmod command. The special permission is assigned to a directory and its dependent files for executing the particular command. The GUID permission for a directory to create the file or such directory into the existing directory.

 

 

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