Pass the RedHat RHCT RH033 Questions and answers with CertsForce

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.

The default tool for email and groupware in Red Hat Enterprise Linux is called Evolution. Evolution provides not only the email access, but also the ability to maintain a calendar, tasklist and contacts database.

What is Evolution?

Evolution is a full-featured personal and workgroup information management tool for Linux systems, and is the default email client for Red Hat Enterprise Linux. It provides all of the standard email client features, including powerful mailbox management, user-defined filters, and quick searches. Its additional feature is a flexible calendar/scheduler, which allows users to create and confirm group meetings and special events online.

Answer option C is incorrect. Thunderbird is a graphical mail client that offers email, Usenet and rss support but it does not support groupware features. Thunderbird is provided along with Firefox and others as part of the Mozilla suit of application.

What is groupware?

Groupware refers to programs that help users work together collectively while located remotely from each other.

Groupware services can include the sharing of calendars, collective writing, e-mail handling, shared database access, electronic meetings with each user able to see and display information to others, and other activities. Sometimes called collaborative software, groupware is an integral component of a field of study known as Computer-

Supported Cooperative Work or CSCW.

Answer options A and D are incorrect. The mutt and pidgin are Non-GUI mail clients.

What is mutt? mutt is a powerful tool for managing email within a text-only environment. This tool is very important to access email even when a graphical interface is not available. Some of its strengths are handling of message threads and flexibility. When mutt sees a series of related messages, it displays each reply under the parent. mutt supports sending of attachments through a mail. The following example describes how a file can be attached to a mail: echo "Sending an attachment." | mutt -a backup.zip -s "attachment" local@domain.com

This command will send a mail to local@domain.com with the subject (-s) "attachment", the body text "Sending an

attachment.", containing the attachment (-a) backup.zip.

What is Pidgin?

Pidgin is a multi-protocol Instant Messaging client that allows a user to use all of his IM accounts at once. It is a free software that can work with AIM ,Gadu-Gadu, Jabber, ICQ ,IRC, MSN, SILC, XMPP, Yahoo!, and Zephyr Network. Anyone is

free to use it and modify it, but if a user distributes his modifications, he must distribute the modified source code as well.

The license of this communication software is Freeware, i.e. anyone can freely download and use this communication software.

You can view all running processes with the help of the ps -aux command. Hence, any of the ps –aux commands (i.e., ps -aux | grep cc, ps -aux

| more, or ps -aux) can be used to check whether the cc process is running on the computer.

Answer option B is incorrect. The tail command is used to display the last few lines of a text file or piped data. It has a special command line option -f (follow) that allows a file to be monitored. Instead of displaying the last few lines and exiting, tail displays the lines and then monitors the file. As new lines are added to the file by another process, tail updates the display. This is particularly useful for monitoring log files. The following command will display the last 10 lines of messages and append new lines to the display as new lines are added to messages: tail -f /var/adm/messages

The LPRM command is used to remove a file from a print queue.

Answer option D is incorrect. The LPQ command reports the status of a print queue.

Answer option A is incorrect. The LPR command is used to submit a file for printing.

Answer option B is incorrect. There is no command such as LPQDEL in Linux.

You will use find ~ -perm -002 -exec chmod o-w {} \; command to fix other writable files in your home directory.

Answer option B is incorrect. The find /home -type d -ls command is used to do an ls -l style listing of all directories in /home/.

Answer options A and D are incorrect. There are no such commands in Linux.

pgrep looks through the currently running processes and lists the process IDs that match the selection criteria to stdout. All the criteria have to match. pkill is a tool that looks up or signals processes based on name and other attributes. Pkill will send the specified signal (by default SIGTERM) to each process instead of listing them on stdout.

Answer option A 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:

Answer option C is incorrect. The sort command is used to print the lines of its input or concatenation of all files listed in its argument list in sorted order. Sorting is done based on one or more sort keys extracted from each line of input. By default, the entire input is taken as the sort key. The blank space is taken used as the default field separator in the output of the sort command.

The -r flag, however, reverses the sort order. For example, the ls -s | sort -nr command will sort the directories of the root directory in reverse order of size.

If no path is given, find looks in the current directory and its subdirectories. Using the -i option tells the find command to perform caseinsensitive search for files named snow.html. It will show all files named snow.html, Snow.html,

SNOW.html in the current directory.

Answer option B is incorrect. This command will only search for files named snow.html in the current directory with case-sensitiveness. It will not search for those files named Snow.html, SNOW.html.

Answer option C is incorrect. This is an incorrect command; it will show an error message.

Answer option D is incorrect. This is also an incorrect command, there should be a name after -i in the command.

All these information are stored in the /etc/passwd file.

What is the /etc/passwd file?

In Linux operating systems, the /etc/passwd file lists information about each of the users that may login to the system. The file is so named because originally it also contained the data used to verify passwords. However, on

modern Unix systems, the security-sensitive password information is instead often stored in a different file using shadow passwords.

The /etc/passwd file typically has world-readable permissions, though it may only be edited by the

superuser or by using a few special purpose commands.

The first field is the user name. Each record in the file must have a unique user name field.

The second field stores information used to confirm a user's password; however, in most modern uses, this field is usually set to "x" (or some other indicator) with the actual password information being stored in a separate shadow password file.

The third field is the user identifier, the number that the operating system uses for internal purposes. It does not have to be unique.

The fourth field is the group identifier. This number identifies the primary group of the user; all files that are created by this user will initially belong to this group.

Reserved gecos ID (Typically, this is a set of comma-separated values including the user's full name

and contact details).

The sixth field is the path to the user's home directory.

The seventh field is the shell program that is started every time the user logs into the system.

Answer option C is incorrect. The shadow password is stored in the /etc/shadow file.

What is /etc/shadow file?

The /etc/shadow file stores the account information in the following format:

The traceroute -w command is used to make traceroute wait 5 seconds (default) for a response to a packet.

What is traceroute?

Traceroute is a route-tracing utility that displays the path an IP packet takes to reach its destination.

It uses Internet

Control Message Protocol (ICMP) echo packets to display the Fully Qualified Domain Name (FQDN) and the IP address of each gateway along the route to the remote host. Traceroute sends out a packet to the destination computer with the TTL field value of 1. When the first router in the path receives the packet, it decrements the TTL value by

1. If the TTL value is zero, it discards the packet and sends a message back to the originating host to inform it that the packet has been discarded. Traceroute records the IP address and DNS name of that router, and sends another packet with a TTL value of

2. This packet goes through the first router, and then times out at the next router in the path. The second router also sends an error message back to the originating host. Now, the process starts once again and

traceroute continues to send data packets with incremented TTL values until a packet finally reaches the target host, or until it decides that the host is unreachable. In the whole process, traceroute also records the time taken for a round trip for each packet at each router.

Answer option B is incorrect. The traceroute -T command uses the TCP/SYN packets for probing.

Answer option C is incorrect. The traceroute -q command sets the number of probe packets per hop.

The default value is 3.

Answer option D is incorrect. The traceroute -r command bypasses the normal routing tables and sends the probe packet directly to a host on an attached network. If the host is not on a directly-attached network, an error is returned. This option can be used to ping a local host through an interface that has no route through it.

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 A 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:

Answer option B is incorrect. The bg command can be used to resume in the background when a process is suspended.

Answer option C is incorrect. There is no such command as job.