RedHat RH033 Dumps

The rm *[0-9] command deletes all files whose names end with a number.

Answer option B is incorrect. The rm [^0-9] command deletes all files except those having names ending with a number.

Answer option C is incorrect. The rm ^[0-9] command deletes all files whose names begin with a number.

Answer option D is incorrect. The rm [0-9]* command also deletes all files whose names begin with a number.

The tail or tail -10 command can be used to see only the last ten lines of a file. The tail -n command is used to see the last n lines of a file. By default, the tail command shows the last 10 lines of a file.

Answer options A and C are incorrect. The head or head -10 command can be used to see only the first ten lines of a file. The head –n command is used to see the first n lines of a file. By default, the head command shows the first 10 lines of a file.

The /etc/profile shell script is the first startup script run when a login shell is started. It runs only for the login shell.

What is a Login shell?

A login shell is a shell that is started by login into the system. The login shells' responsibility is to start the non-login shell

and to make sure that environment variables are set so as to ensure that a user can get all the default parameters needed at start-up.

Login shell will set the PATH environment variable, TERM, the UID and GID of the terminal amongst other things. These are the requirements in order to work proficiently. Additionally, the login-shell will set default variable such as USERNAME,

HISTSIZE, HOSTNAME, HOME, etc.

Answer option A is incorrect. The ~/.bashrc shell script is the first startup script run when a non-login shell is started.

A non-login shell is a shell started by a user or a program issuing the bash command.

Some non-login shells are as follows:

su

graphical terminals

executed scripts

any other bash instances

Answer options D and B are incorrect. The non-login shells first call ~/.bashrc. The ~/.bashrc calls

/etc/bashrc, and then /etc/bashrc

calls /etc/profile.d.

When you will execute find -name "*.conf" -exec cp {} {} .orig \ ; command on the terminal, it will back up configuration files from the current directory and a .orig extension.

What is the find command?

The find command can perform a search based on a variety of search limitations. It searches through one or more directory tree(s) of a filesystem, locating files based on some user-specified criteria. By default, find returns all files in the current working directory. Further, find allows a user to specify an action to be taken on each matched file.

Thus, it is an extremely powerful command for applying actions to many files.

The find command can be used with a wild card (*), but it works best when we know the name of the file or directory we are looking for.

The find command can search your system for files that comply with certain numeric criteria, such as the size of the file (- size), the number of links to the file (-links), the date of the last change to the files data (-mtime), or the date of the last time the file was read (-atime). All these criteria accept a numeric value. When a numeric value is provided to find, it looks for an exact match, more than the number, or less than the number.

Answer options B and A are incorrect. These options are invalid.

Answer option D is incorrect. To fix other-writable files in your home directory, you will run find ~ - perm -002 -exec chmod o-w {} \;.

According to the scenario, the S status message shows that the process id 24224 is in sleeping status.

The ps -aux command reports the status of processes currently running on a Linux computer. It shows the following status messages:

You will use the tee command to write its content to standard output and simultaneously copy it into the specified file. The tee command is used to split the output of a program so that it can be seen on the display and also be saved in a file.

It can also be used to capture intermediate output before the data is altered by another command or program. The tee command reads standard input, then writes its content to standard output, and simultaneously copies it into the specified file(s) or variables. The syntax of the tee command is as follows: tee [-a] [-i] [File] where, the -a option appends the output to the end of File instead of writing over it and the -i option is used to ignore interrupts.

Answer option C is incorrect. The concatenate (cat) command is used to display or print the contents of a file.

Syntax: cat filename

For example, the following command will display the contents of the /var/log/dmesg file:

cat /var/log/dmesg

Note: The more command is used in conjunction with the cat command to prevent scrolling of the screen while displaying the contents of a file.

Answer option A is incorrect. The less command is used to view (but not change) the contents of a text file, one screen at a time. It is similar to the more command. However, it has the extended capability of allowing both forward and backward navigation through the file. Unlike most Unix text editors/viewers, less does not need to read the entire file before starting; therefore, it has faster load times with large files.

The command syntax of the less command is as follows: less [options] file_name

Where,

Answer option D is incorrect. The more command is used to view (but not modify) the contents of a text file on the terminal screen at a time.

The syntax of the more command is as follows: more [options] file_name

Where,

SELinux is an operating system based on Linux which includes Mandatory Access Control. The

SELinux provides Kernel-level security for Red Hat Enterprise Linux.

Answer options C, B, and A are incorrect. These are the features of SELinux.

What are the features of SELinux?

The features of SELinux are as follows:

SELinux provides Kernal-level security.

SELinux implements Mandatory access control (MAC) security in Red Hat Enterprise Linux.

SELinux assigns every file and process on the system a context, identifying its type and purpose.

SELinux enforces a policy that dictates which actions a given type of process may take on a given type of file

SELinux applies to all users, including root.

Kernel files do not change regularly and therefore are contained in the /boot directory, not in the

/var directory.

What is the /var directory?

According to the Filesystem Hierarchy Standard, the /var directory contains regularly-changing system files. This comprises spool directories and files, and administrative and logging data.

Answer option A is incorrect. System log files are stored in the /var directory.

Answer options D and C are incorrect. Print spool files and email-spools are variable data files and therefore are contained in the /var directory.

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.

aspell is a utility that can function as an ispell -a replacement, as an independent spell checker, as a test utility to test out Aspell features, and as a utility for managing dictionaries.

Syntax:

aspell [options]

Some important options used with aspell are as follows:

Answer option B is incorrect. The nice command is used to change the priority of a process in the kernel's scheduler. A niceness of -20 is the highest priority and 19 is the lowest priority. The default niceness for processes is inherited from its parent process, usually 0. For example, when specifying a very low priority, the following command can be entered: nice -n 19 cc -c *.c &

The above command runs the cc command in the background at a lower priority than the default priority set by the nice command.

Answer options D and A are incorrect. There are no such spell checkers as inspell and spell.

The bg utility resumes suspended jobs from the current environment by running them as background jobs if job control is enabled. If the job specified by job_id is already a running background job, the bg utility will have no effect and shall exit successfully. Using bg to place a job into the background will cause its process ID to become "known in the current shell execution environment", as if it had been started as an asynchronous list.

Answer option D is incorrect. The fg utility continues a stopped job by running it in the foreground, some shells are not able to run this command.

Syntax:

fg [%job] Where %job specifies the job that a user wants to run in the foreground.

Answer option A is incorrect. The jobs command lists the jobs that are running in the background and in the foreground. If the prompt is returned with no information, no jobs are present.

Syntax: jobs [-p | -l] [-n] [-p] [-x] [job id]

Some important options used with jobs command are as follows:

Answer option C is incorrect. The top command is used to produce a frequently-updated list of processes. By default, the processes are ordered by percentage of CPU usage, with only the "top" CPU consumers shown. This command shows how much processing power and memory are being used, as well as other information about the running processes. The following figure demonstrates the output of the top command:

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 service and chkconfig commands are used to start and stop a service, and to ensure persistence across reboots. The service command is used to abstract the management of services provided by the system. It can be used to start and stop services, as well as to determine the status of services. To execute a given command for a given service, it uses the start, stop, restart, and reload arguments. Some important options used with the service command are as follows:

The chkconfig tool is used to update and query runlevel information for system services.

Answer option D is incorrect. The yum command automatically attempts to check all configured repositories to resolve all package dependencies during an installation/upgrade.

Answer option B is incorrect. The tape archive (tar) command combines a large number of files into a single file for archival purposes.

This command will execute a program named My_program and whatever errors are generated while executing that program will all be added to a file named file2 rather than being displayed on the screen.

What is redirection of STDIN, STDOUT, STDERR in Linux?

Redirection means diverting data from their normal destination to another. Whenever a program is executed on terminal some output is displayed at the shell prompt. In case a user does not want that output to appear in the shell window, the user can redirect it elsewhere. The user can redirect the output into a file, printer, etc.

Not only the output of programs is redirected, but also input of a program and error messages are redirected to a file.

Common Redirection operators are as follows:

Answer option D is incorrect. This command will direct the standard output of My_program to file2.

Answer option A is incorrect. This command will append the standard output of My_program to file2.

Answer option C is incorrect. This command cannot be applied in this scenario.

The lpq command views the content of a print queue.

Answer option D is incorrect. The lpr command sends a job to the queue to be printed.

Answer option A is incorrect. The lprm command removes a job from the queue.

Answer option B is incorrect. The lpstat -a command lists the configured printers.

You can use the file command to display the file types of all the files in a directory at a time. In order to accomplish the task, you will have to issue the following command:

file *

What is the file command?

The file command is used to analyze the files specified in the argument.

Syntax:

file [] [] ...

By providing the name of a file as an argument, the file command analyzes the file. The file command supports multiple arguments. The asterix (*) metacharacter can also be used with the file command.

Answer option C is incorrect. In Linux, the mount command is used to mount and display disks, partitions, and file systems. Mounting refers to the process in which the operating system prepares the media to be read.

Answer option A is incorrect. The File System Check (fsck) command is used to scan all disks and partitions, and it repairs them if required. The fsck command should be run only on an unmounted file system.

Answer option D is incorrect. The init command is used to switch a Linux computer to different run levels.

The Ctrl+Alt+Backspace key combination is used to terminate the X session.

Answer option A is incorrect. The Ctrl+Alt+F7 key combination is used to switch from a virtual console back to the X terminal.

Answer option C is incorrect. The Ctrl+Alt+Fn key combination is used to switch from graphical mode to the nth (n varies from 1-6) virtual console running in text mode.

Answer option D is incorrect. Ctrl+Alt+A is not a valid key combination to terminate the X session.

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. Instead of the arrow keys, you can also use

vi's traditional h, j, k and l keys for the same effect.

Answer options B and A are incorrect. 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 D is incorrect. Ctrl-w, q is used to quit from your current window.

The -c option with the wc command is used to count the number of bytes in a file. It shows only the number of bytes used by a file.

Answer option A is incorrect. The -l option with the wc command is used to count the number of lines in a file. It shows only the number of lines in a file.

Answer option D is incorrect. The -w option with the wc command is used to count the number of words in a file. It shows only the number of words in a file.

Answer option C is incorrect. The -m option with the wc command is used to count the number of characters in a file.

The evince utility is used to view PDF files on the Linux operating system.

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]

Answer options B and D are incorrect. These commands are used to convert a text to PostScript and send it to a file or the print queue.

What is PostScript?

PostScript is a language developed by Adobe Systems for printing documents on laser printers. It can also be adapted to produce images on other types of devices. It is the standard for desktop publishing. Every PostScript printer contains a built-in interpreter that executes PostScript instructions. Level 1, Level 2, and PostScript 3 are three basic versions of PostScript language.

Answer option A is incorrect. The ps2pdf utility is used to create PDF files.

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 scp command is used to copy files from one host to another over the network.

What is the scp command?

The scp command is used to copy files over ssh connections. This is pretty useful if a user wants to transport files between computers, for example, to backup a file. The scp command uses the ssh command to copy files over the network.

Syntax:

# scp [options] source destination

Where, source refers to the file which a user wants to copy from his current computer/directory, and destination refers to the home directory of the remote system where a user wants to copy the file.

Some important options used with the scp command are as follows:

Answer option A is incorrect. The ls command in Linux lists information about files (the current directory by default).

Answer option C is incorrect. The mutt command is used to manage email within a text only environment.

Answer option B is incorrect. The cat command is used to join multiple files together and display the result on the screen.