Page 53 - DCAP106_OPERATING_SYSTEM_TOOLS

Operating System Tools

Notes Self Assessment

Fill in the blanks:
12. A ..................................... is defined as an independent program entity which executes and
makes use of computer resources like CPU time and memory.
13. A special message that is sent to the process by the existing process is known as a ..............
........................
2.7 Managing Users

Usually, a desktop is made to be utilized by people. Users that are familiar with the operating
systems such as Windows 9x, Windows Me, etc. will consider Red Hat Linux a more severe
organization of permissions that depict what every user can do and vice-versa. This is to note
that the processes and data of one user cannot be used or altered by other users. This can be done
only if they are allowed to do so.

2.7.1 Concept of User Management

As we know, the root of the computer can use all the resources of the computer. Thus, many
security restrictions are there in the system in order to make sure that this user privilege is not
compromised. A system administrator should also use system as a less privileged user. He
should use super user privileges only when required.
Just one user can work physically at the desktop and other users can log in via network services
such as telnet and ssh.
Linux provides the simple method of organizing users. Each user can be the part of one or more
groups. Thus, as apart from protecting a resource by enforcing permissions to individual users,
we can also put users into a group and enforce permissions to the group.

2.7.2 Understanding Permissions

As we know privileges are needed to control other user’s processes; the same goes for files and
directories. Each file as well as directory is connected with a single user and also with a group.
There are three classes of users which are provided specific permissions to use a file:

z z The owner
z z The group members
z z Everybody else
All the three classes of users are allowed a mixture of three types of access permissions:

Table 2.2: Three Types of Access Permissions
Permission Meaning when applied to files Meaning when applied to directories
Read It allows the user to read the contents of It allows the user to list the contents of the
the file directory
Write It allows the user to change the It allows the user to create or remove files
contents of the file within the directory
Execute It allows the user to execute the file It allows the user to access files as well as
subdirectories

46 LOVELY PROFESSIONAL UNIVERSITY