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Caution using root access

4.7 Perform administrative tasks while logged in as root, or by using the su command (e.g., understand commands that are dangerous to the system)

Root access is required to perform most Linux administrative tasks. However, the powers of root access are unlimited and can permanently damage the system if performed incorrectly. Therefore, the common and “best practice” method for providing root access in Linux or UNIX is to log in as a user and then use the su (switch user) command to change to the root user, perform the required task, and then exit root privilege.

You can use the su (switch user) command to move from any user login to another. If a user name is not given, the su command defaults to change to the root user. This command asks for the root password and provides all the necessary abilities. Notice that the prompt changes from a $ for users to # for the root user.

Even when performing routine tasks with root access, use due care to ensure that the system is backed up and user files are protected.

Navigating the GUI interface

4.17 Manage and navigate the Graphical User Interface (e.g., menus, xterm)

Most Linux tasks can be performed in the X Window System, which requires you to be able to navigate the GUI interface. Today, most distributions use the GNOME or KDE desktop environment and provide many tools necessary for performing extensive management of the Linux system. Each distribution also provides its own tools to perform administrative tasks. The basic navigation of the system requires the use of a terminal session, which provides access to the command line in the GUI. Most instances of the GUI allow the right mouse button to provide a menu that allows you to select a terminal, or by using the standard GUI menus to select a terminal. This is typically called an “xterm”, to denote a terminal within an X Windows session.

The neutrality of the Linux+ exam limits the questions on navigating the GUI interface, so be prepared for only very general questions about GUI interfaces.

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Summary

This chapter explains many of the basics of Linux system navigation, including the use of terminals, virtual consoles, shell navigation, and remote access. For the exam, keep these points in mind:

Multi-user environments

•Virtual Consoles (or VCs)

•Serial Terminals

•Ethernet Terminals and the Linux Terminal Server Project

Shell, scripts, and scheduling

•BASH

•Creating scripts

•Cron and crontab to schedule tasks

Administration and navigation

•Root access

•GUI navigation

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STUDY GUIDE

The Study Guide section provides you with the opportunity to test your knowledge about the Linux+ exam objectives that are covered in this chapter. The Assessment Questions provide practice for the real exam, and the Scenarios provide practice with real situations. If you get any questions wrong, use the answers to determine the part of the chapter that you should review before continuing.

Assessment Questions

1.What keystroke is normally used to move from one virtual console to another virtual console?

A.<Ctrl> <Tab>

B.<Alt> <Fx>, where x is the console number

C.<Alt> <Tab>

D.<Ctrl> <Fx>, where x is the console number

2.How many virtual consoles does Linux normally support?

A.32

B.48

C.63

D.256

3.What can you use to provide a simple way to utilize low-cost workstations as either graphicalor text-based terminals in a Linux environment?

A.Virtual Consoles

B.Samba Server

C.DHCP Server

D.Terminal server

4.When creating terminals with a diskless or Ethernet client, how does the client receive the kernel from the server?

A.tftp

B.ftp

C.DHCP

D.bootp

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5.Which file can be modified to allow Linux to provide more than the default number of virtual consoles?

A./etc/rc.d/init.d/syslog

B./etc/inetd.conf

C./etc/inittab

D./tftpboot/lts/ltsroot/etc/lts.conf

6.What services are used to provide IP addresses for clients on a terminal server system? (Choose all that apply.)

A.bootp

B.DNS

C.DHCP

D.NFS

7.What additional package may be used to help support the creation of terminals for the LTSP system?

A.lts_core

B.Etherboot

C.XDM

D.syslogd

8.What program may be used to monitor connections to a Linux system?

A.tracert

B.nbstat

C.ipconfig

D.netstat

9.BASH has incorporated useful features from what other shells? (Choose all that apply.)

A.ksh

B.tcsh

C.z-shell

D.csh

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10.Where is the bash executable usually stored?

A./.bashrc

B./.bash_profile

C./bin/bash

D./etc/bash

11.What daemon is used to schedule automated tasks on a Linux system?

A.crontab

B.cron

C.cron.d

D.crontab.d

12.Which of the following indicates that the file is a shell script?

A.#!/bin/sh

B.#script

C.!!/bin/bash

D.* script *

13.What command may be used to move from one login to another without logging out?

A.vi

B.su

C.chmod

D.chuser

14.What provides access to other command line interfaces in a Linux system?

A.<Alt> <Fx> where x is the number of the virtual console

B.Command Prompt

C.Only logging out to a command line

D.Terminal

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15.What is the Linux Terminal Server Project package name?

A.ltsp_initialize

B.ltsp

C.lts_core

D.mknbi-linux

16.What command is used to install the package lts_core-2.XX-XX.i386.rpm?

A.rpm -i lts_core-2.XX-XX.i386.rpm

B.rpm -I lts_core-2.XX-XX.i386.rpm

C.rpm -e lts_core-2.XX-XX.i386.rpm

D.rpm -u lts_core-2.XX-XX.i386.rpm

17.Which of the following lines in the inittab file will create a virtual terminal that may not be a local connection to the Linux system?

A.S2:3:respawn:/sbin/uugetty ttyS2 M19200

B.2:2345:respawn:/sbin/getty tty2 VC linux

C.# S2:3:respawn:/sbin/uugetty ttyS2 M19200

D.# 2:2345:respawn:/sbin/getty tty2 VC linux

18.Which file does the lts_core package create that may add in the starting of the DHCP service?

A./etc/bootptab

B./etc/dhcpd.conf.example

C./etc/dhcpd.conf

D./etc/dhcp/dhcpd.leases

19.What should be installed on any network using LTSP service to prevent vulnerability to unauthorized outside access?

A.XDM

B.firewall

C.router

D.portmapper