OPERATING SYSTEM

Write the step of adding and maintaining new user in Unix/Linux system?

There are three types of accounts on a Unix system:

  1. Root account: This is also called super user and would have complete and unfettered control of the system. A super user can run any commands without any restriction. This user should be assumed as a system administrator.
  2. System accounts: System accounts are those needed for the operation of system-specific components for example mail accounts and the sshd accounts. These accounts are usually needed for some specific function on your system, and any modifications to them could adversely affect the system.

3.      User accounts: User accounts provide interactive access to the system for users and groups of users. General users are typically assigned to these accounts and usually have limited access to critical system files and directories.

UNIX supports a concept of Group Account which logically groups a number of accounts. Every account would be a part of any group account. UNIX group’s plays important role in handling file permissions and process management.

Managing Users and Groups:

There are three main user administration files:

  1. /etc/passwd: Keeps user account and password information. This file holds the majority of information about accounts on the Unix system.
  2. 2.      /etc/shadow: Holds the encrypted password of the corresponding account. Not all the system supports this file.
  3. /etc/group: This file contains the group information for each account.
  4. /etc/gshadow: This file contains secure group account information.

How many types of commands are there in Unix/Linux?

There are two kinds of commands used in Linux: Built-in Shell Commands and Linux Commands.

Shell Command Library 
Linux Command Library

The Linux / UNIX operating systems come with many commands that the user can enter into the computer from the keyboard and use to interact with the computer. There are two kinds of commands that come with a Linux / UNIX operating system: Shell Commands and Linux/Unix Commands. Here is a comparison of the two:

Built-in Shell Commands:

  • What are they?
    They are part of a shell. In other words, each shell (e.g., C Shell, Bourne Shell and Korn Shell) has a set of commands built into its program.
  • Are the shell commands always the same on every computer? 
    Though shell commands may vary from one shell to another, the commands within each shell stay the same across Linux / UNIX distributions and variants.
  • Where do I enter shell commands? 
    The user types shell commands at the shell prompt, the default of which is % for the C Shell, and $ for the Bourne Shell and the Korn Shell.
  • Are these also part of the shells? 
    No. Each Linux / UNIX command is a separate executable program. They are written in C, or less likely, in other programming languages.
  • Where are they stored? 
    They are located in special directories for binary files, such as /user/bin. Directories that contain these Linux / UNIX commands are listed in the search path, which the shells use to find them.
  • Are Linux / UNIX commands the same on every computer? 
    Commands may vary from one Linux distribution to another and one UNIX flavor to another. You use these commands (original or added) the same way independent of the shell you are currently in.

Unix Commands

 

  • Are these also part of the shells? 
    No. Each Linux / UNIX command is a separate executable program. They are written in C, or less likely, in other programming languages.
  • Where are they stored
    They are located in special directories for binary files, such as /user/bin. Directories that contain these Linux / UNIX commands are listed in the search path, which the shells use to find them.
  • Are Linux / UNIX commands the same on every computer? 
    Commands may vary from one Linux distribution to another and one UNIX flavor to another. You use these commands (original or added) the same way independent of the shell you are currently in.

What is the function and responsibilities of system administrator?

Duties of a system administrator

The duties of a system administrator are wide-ranging, and vary widely from one organization to another. Sysadmins are usually charged with installing, supporting, and maintaining servers or other computer systems, and planning for and responding to service outages and other problems. Other duties may include scripting or light programming, project management for systems-related projects.

The system administrator is responsible for following things:

1.      User administration (setup and maintaining account)

2.      Maintaining system

3.      Verify that peripherals are working properly

4.      Quickly arrange repair for hardware in occasion of hardware failure

5.      Monitor system performance

6.      Create file systems

7.      Install software

8.      Create a backup and recovery policy

9.      Monitor network communication

10.  Update system as soon as new version of OS and application software comes out

11.  Implement the policies for the use of the computer system and network

12.  Setup security policies for users. A sysadmin must have a strong grasp of computer security (e.g. firewalls and intrusion detection systems).

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s