RH033 Red Hat Linux Essentials Questions and Answers

The ps command reports the status of processes that are currently running on a Linux computer.

What is > command?

The > command is used for storing the output generated by different commands. It creates a file specified to store the output. If the specified file already exists, it overwrites that file.

The ps2pdf utility is used to convert PostScript to a PDF file.

What is a ps2pdf command?

The ps2pdf command creates PDF files. It is used to convert a PostScript file to a PDF file.

There are a number of versions of this program, some are as follows:

Answer option D is incorrect. The enscript utility converts a text to a PostScript format and sends it to a file or the print queue.

Answer option B is incorrect. The evince utility is used to view a PDF file, not to create a PDF file.

What is the evince command?

The evince command is a document viewer capable of displaying multiple and single page document formats such as PDF and Postscript.

Syntax: evince [Options] [Filename]

The cp -u command copies only when the source file is newer than the destination file or when the destination file is missing.

Answer option C is incorrect. The cp -p command copies the files from source to destination with preserving file attributes, such as timestamps, mode, and ownership.

Answer option B is incorrect. The cp -l command links files from source to destination instead of copying.

Answer option D is incorrect. The cp -s command makes symbolic links instead of copying.

The Ctrl-r key-combination is used to redo a change undone by a u command in vim. You can go back in time with the undo command. You can then go forward again with the redo command. If you make a new change after the undo command, the redo will not be possible anymore.

Answer options B and D are incorrect. The Ctrl-w, s and Ctrl-w, v key-combinations are used to view a file in two windows in a single vim screen. Ctrl-w, s splits the screen horizontally and Ctrl-w, v splits the screen vertically.

Answer option A is incorrect. The Ctrl-w key-combination with an arrow key is used to jump from one window to another. This will move you to the next window in whichever direction the arrow would normally move your cursor.

The chmod command is used to change or edit file/folder permissions in Linux. In order to accomplish the task, you will have to run the following command:

chmod 754 report

This will provide Read, Write, and Execute permissions to the owner (in this case, David), Read and

Execute permissions to the members of the JAdmin group, and only Read permission to other users.

Answer option D is incorrect. This will provide Read, Write, and Execute permissions to David, to the members of the JAdmin group, and to other users.

Answer option A is incorrect. This will provide Read and Execute permissions to David, to the members of the JAdmin group, and to other users.

Answer option C is incorrect. The chown command is used to change the ownership on files or folders.

The lprm - and lprm -a all commands can be used to delete all jobs queued in a printer. The lprm command is used to remove the print jobs that have been queued for printing. If no arguments are supplied, the current job on the default destination is cancelled. The command syntax for the lprm command is as follows:

lprm [-E] [-U username] [-h server[:port]] [-P destination[/instance]] [-] [job ID(s)]

where,

Answer options B and C are incorrect. These are not valid lprm command syntaxes.

The ifdown command is used to set down the interface and flush all its addresses. It is possible to let

ifdown check the interface if the interface is still used before setting it down. If the interface is used it may then discard the using processes or refuse setting it down.

To enable this feature, check /etc/sysconfig/network/config file.

Answer option A is incorrect. The ifup command is used to bring up a preconfigured interface for networking. It is usually invoked by the network script at boot time or by the PCMCIA/hotplug system. It can also be used to start interfaces manually on the command line. It activates the link, adds addresses and other parameters and sets up the routes for an interface.

Answer option C is incorrect. The ifconfig commands displays the basic settings of a network device.

Answer option D is incorrect. There is no such command as down.

According to the scenario, John will use the chgrp bar foo command to accomplish the task. The chgrp (from change group) command is used by unprivileged users to change the group associated with a file. Unlike the chown command, chgrp allows regular users to change groups, but only to one of which they are a member. The general syntax of the chgrp command is as follows:

chgrp group target1 [target2 ..]

The group parameter indicates the new group with which the targets should be associated.

The target1 parameter indicates the files or directories for which the change should be made.

The target2 parameter indicates the optional additional files or directories for which the change should be made.

For example:

The above command changes the group associated with ttt to 'system', provided the executing user is a member of that group.

Answer option A is incorrect. In the chgrp command, first we write the group name and after that, we write the file name. But here just the opposite is written, so this command will not give the desired result.

Answer options D and B are incorrect. There is no such command as chgroup in Linux.

The Interface configuration files are read by system-config-network, ifup, ifdown, and other tools that bring network interfaces up and down.

Answer option B is incorrect. The system-config-services tool is used to manage services in Linux.

The ls -al /root command lists all the files and directories, including hidden files in the /root

directory, in long listing format. /root is the root

user's home directory.

What is the ls command?

The ls command is used to list files on a Linux computer. The syntax of the ls command is as follows:

ls [option] [directory name]

Several options are used with the ls command. Following is a list of some important options:

For example, the following command displays all the files (including hidden files) in the /home

directory and the contents in

the subdirectories:

ls -aR /home

Answer option B is incorrect. The ls command without arguments lists the file and directory names

in the current directory.

Answer option C is incorrect. The ls -s /root command shows the size of all files and directories (in blocks, not bytes) that reside in the /root directory.

Answer option D is incorrect. The ls -h /root command shows the size of files and directories in

"human readable format" (i.e. 19M, 3G, etc).

Answer option C is incorrect. The pdf2ps utility is used to convert a PDF file to a PostScript.

The date command with the %M specifier prints the current time (Minutes). Since the output is redirected towards the date.txt file, the current time (Minutes) will be printed in the date.txt file.

According to the scenario, you will use the wc -c file1.txt 2>error.txt command to accomplish the task. The 2> operator is an error redirector, which, while running a command, redirects the error (if it exists) on the specified file.

Answer options D and B are incorrect. The > or 1> redirector can be used to redirect the output of the wc -c file1.txt file to the error.txt file; however, you want to write the errors in the error.txt file, not the whole output.

Answer option A is incorrect. The >> operator will redirect the output of the command in the same manner as the > or 1> operator. Although the >> operator will not overwrite the error.txt file, it will append the error.txt file.

This command will prompt you to remove Joe's tmp files that are 3 days older. When the -ok option is used with the find command it causes find to execute the rm command once for each /tmp file that is 3 days older. {} can be used as a filename placeholder.

The -ok option with the find command is used to execute a command once for each file that matches the given criteria. This is commonly used in situations such as removing files or renaming files to have a certain extension. The -ok option causes find to ask for each file before removing it.

What is the find command?

The find command is a versatile method for locating files on a file system. The syntax for this command is as follows:

find -

Some of the important criteria are described in the table below:

What are some numeric criteria that the find command uses?

The find command can search your system for files that comply with certain numeric criteria. For

example, -ctime, -atime, -

cmin, -amin, etc. The -ctime and -atime are measured in days and the -cmin and -amin are measures in minutes.

For example:

find /tmp -ctime +10

This command searches for files that are more than 10 days older.

find /tmp -cmin +10

This command searches for files that are more than 10 minutes older.

What is the purpose of using \; at the end of the find command?

The purpose of using \; at the end of the find command is that when find is used with -exec and –ok the find command uses ; as the delimiting character. Unfortunately ; is also a delimiting character for the bash shell so we must prevent bash from interpreting it. When a character is preceded with a backslash (\), bash instructs it literally, so typing \; at the bash command prompt will send ; to find command after bash has done its interpretation.

Answer option A is incorrect. This command will prompt you to remove Joe's tmp files that are 3 minutes older.

Answer options D and B are incorrect. These are the incorrect command syntaxes.

Open source software is software that has been released under an Open Source Initiative (OSI) certified license. The definition includes 10 criteria, which are described as follows:

Open source software is software that has been released under an Open Source Initiative (OSI) certified license. The definition includes 10 criteria, which are described as follows:

1. Free Redistribution: The license allows any party selling or giving away the software as a component of an aggregate software distribution comprising programs from many different sources.

2. Source code: Anyone can modify the source code.

3. Derived Works: The license must allow changes and derived work under the same conditions as the license of the original software.

4. Integrity of the authors source code: To maintain the integrity of the original authors work, the license may require that changes to the code be provided in patch form.

5. No Discrimination Against Persons or Groups: The license must be nondiscriminatory with respect to persons or group of persons.

Therefore, open source license are forbidden from locking anyone out of the process.

6. No Discrimination Against Fields of Endeavor: The license must not restrict anyone from making use of the software in a specific field of endeavor.

7. Distribution of License: The license can be distributed to all but the rights attached to that program must apply to all to whom the program is distributed. And no party can execute any additional license.

8. License Must Not Be Specific to a Product: It may not require that the software be part of particular distribution.

9. License Must Not Restrict Other Software: It may not restrict other non-open source software.

10. License Must Be Technology-Neutral: It may not require the use of technology to apply the license.

Answer options B and A are incorrect. These are the characteristics of closed source software.

The inode table contains the last access time, last modification time as well as the last inode change time of a file.

What type of data is stored in an inode table?

An inode table contains a list of all files in an ext2 and ext3 filesystem. An inode ( index node) is an entry in the table, containing information about a file (the metadata). Some important data stored in the inode table are as follows:

The file type (regular file, directory, etc.)

File permissions

Link count: The number of file names associated with the inode number.

The user ID number of file owner and the group ID number of the associated group.

Timestamps, including last access time, last modification time, and last inode change time.

Location of the data on the hard disk.

Answer options D, B, and A are incorrect. The inode table contains all these information, the file type, file permissions on the specified file, location of data on the hard disk.

The ipconfig network diagnostic tool is used in the Windows operating system to see IP addresses and MAC addresses, and other related information. It is not used in the Linux operating system. In the place of the ipconfig utility, ifconfig is used in Linux for performing the same task.

Answer option D is incorrect. The ping utility is a network diagnostic tool that checks TCP/IP connectivity on any host. It is used in both Linux and Windows operating systems.

What is the ping utility?

The ping command-line utility is used to test connectivity with a host on a TCP/IP-based network.

This is achieved by sending out a series of packets to a specified destination host. On receiving the packets, the destination host responds with a series of replies. These replies can be used to determine whether or not the network is working properly.

Answer option A is incorrect. This is a network diagnostic tool in Linux that perform hostname to IP address translation and vice versa.

Answer option B is incorrect. This is a network diagnostic tool in Linux which is used to perform hostname to IP address translations, and vice versa in greater detail.

The env command is used to list the environment variables that are set on a Linux computer.

The programs that run on a Linux computer are known as processes. When a user starts a program, a new process is created. This process runs within what is called an environment. A user can set parameters in this environment so that the running program can find the desired values. The following syntax is used to set a parameter to a variable:

VARIABLE=value

This would set a parameter by the name VARIABLE with the value that you provide. Some of the commonly used environment variables are HOME, PATH, PS1, etc.

Answer option B is incorrect. The rm command is used to delete files from a directory on a Linux computer.

Answer option C is incorrect. The ls command is used to list files on a Linux computer.

Answer option D is incorrect. The echo $shell command will provide the name of the current shell that a user is using.

The scp command copies files between hosts on a network. It uses ssh for data transfer, and uses the same authentication and provides the same security as ssh. Unlike rcp, scp will ask for passwords or passphrases if they are needed for authentication. Any file name may contain a host and user specification to indicate that the file is to be copied to/from that host.

Copies between two remote hosts are permitted.

The VI is a visual interactive text editor that allows a user to create, modify, and store files on a Linux computer. It works in the following modes:

Command: This is the default mode of the command. Various commands can be used in this mode to manipulate the opened text.

Input: In this mode, a user can insert text directly in the text screen area.

Answer option D is incorrect. The GNU zip (GZIP) utility is a compression utility that is used to compress files for saving space. It creates files with the .gz extension. It can also compress tar files. In order to unzip files with the .gz extension, the

GUNZIP command is used.

Answer option B is incorrect. The nmap utility, also commonly known as port scanner, is used to view the open ports on a Linux computer. It is used by administrators to determine which services are available for external users. This utility helps administrators in deciding whether to disable the services that are not being used in order to minimize any security risk.

Answer option C is incorrect. MS Word is a Windows-based utility. Hence, it cannot be used in Linux.