Linux

The device file on the third partition on the second SATA hard drive in /dev

/dev/sdb3

save the file with changes and exit VIM

:wq

is a program that interprets commands typed in by the user. Each string typed into the shell can have up to three parts: the command, options (that begin with a - or --), and arguments. Each word typed into the shell is separated from each other with spaces.

Borne Again Shell

The GNOME Shell provides the core user interface functions for the GNOME desktop environment. The gnome-shell application is highly customizable. By default, RHEL 7 users use the "GNOME Classic" theme for gnome-shell, which is similar to the GNOME 2 desktop environment.

GNOME

The GNU Project developed a different online documentation system, known as GNU info.

GNU Info

(Kernel-based Virtual Machine) is a full virtualization solution built into the standard Red Hat Enterprise Linux kernel. KVM provides the virtual machine (VM) technology across all Red Hat products, from standalone physical instances of Red Hat Enterprise Linux up to the cloud OpenStack platform.

KVM

logical volume management. With LVM, one or more block devices can be aggregated into a storage pool called a volume group.

LVM -

The locate command searches a pre-generated database for file names or file paths and returns the results instantly

Locate

NetworkManager is a daemon that monitors and manages network settings.

NetworkManager

is a free and open-source software platform for cloud computing, mostly deployed as an infrastructure-as-a-service (IaaS). The software platform consists of interrelated components that control diverse, multi-vendor hardware pools of processing, storage, and networking resources throughout a data center.

OpenStack

The pinfo reader is more advanced than the original infor command. Designed to match the lynx text web browser keystrokes, it also adds color.

Pinfo

A pipe connects the standard output of the first command to the standard input of the next command.

Pipe -

A process is a running instance of a launched, executable (running) program. A process consists of: • an address space of allocated memory• security properties including ownership credentials and privileges • one or more execution threads of program code, and• the process state

Process

The root user can perform an update of the database with the updated command.

Updated

An absolute path is a fully qualified name, beginning at the root (/) directory and specifying each subdirectory traversed to reach and uniquely represent a single file.

absolute file reference

Bash is a command processor that typically runs in a text window where the user types commands that cause actions. Bash can also read and execute command from a file, called a shell script. Bash is an improved version of one of the most successful shells used on UNIX-lie systems and using bash for executing commands can be powerful.

bash

The blkid command gives an overview of existing partitions with a file system on them and the UUID of the file system, as well as the file system used to format the partition.

blkid

The highest possible address on a subnet (host part is all ones in binary) is used for broadcast messages in IPv4, and is called the broadcast address

broadcast address

NetworkManager provides both a graphical and a command line tool to help users and administrators configure and manage network interfaces. The command line interface for NetworkManager is nmcli

command line interface

Command to run, Options to adjust the behavior of the command and the arguments targets of the command.

command structure

Daemons are processes that wait or run in the background performing various tasks. Generally, daemons start automatically at boot time and continue to run until shutdown or until they are manually stopped. By convention, the names of many daemon programs end in the letter "d".

daemon -

To configure password aging controls and password length, edit /etc/login.defs file. Password length refers to the number of characters needed to have for the password to be allowed.

default password policy -

GNOME 3 desktop environment to run commands from a shell prompt in a terminal program.

desktop environment -

The df -h command reports on the total disk space, used disk space, and free disk space on all mounted regular files systems in a human readable output. The lower case h shows the files sizes in MiB, KiB and GiB units.

df -h

This command shows a disk usage report in human-readable format for the /var/log directory in a server.

du -h

All files on a Linux system are stored on file systems which are organized into a single inverted tree of directories, known as a file system hierarchy.

file system hierarchy

The find command performs a real-time search (scans) in the local file systems to find files that match the criteria of the command-line arguments. The find command is looking at files in the file system as your user account.

find

The desktop environment is the graphical user interface on a Linux system. • The default desktop environment in Red Hat Enterprise Linux 7 is provided by GNOME 3. It provides an integrated desktop for users and a unified development platform on top of a graphical framework provided by the X Window System

graphical user interface

A hypervisor or virtual machine monitor (VMM) is a piece of computer software, firmware or hardware that creates and runs virtual machines.

hypervisor

The id command is used to show information about the current logged-in user. Basic information about another user can also be requested by passing in the username of that user as the first argument to the id command.

id

command used to show device and address information (active interface has a status of UP, link line specifies the hardware (MAC) address of the device, inet line shows the IPv4 address and prefix, the broadcast address, scope, and device name, the inet6 lines shows IPv6 information.

ip addr show eth0

Provides the host and server libraries for interacting with hypervisors and host systems.

libvirt -

Log messages are normally saved in files in the /var/log directory. Log files are maintained by the rsyslog service, and the /var/log directory contains a variety of log files specific to certain services.

logs saved

With the octal notation, each access class gets a digit: the "hundreds" place for (u)ser, the "tens" place for (g)roup, and the "ones" place for (o)ther. • Each permission type gets a value: (r)ead gets 4, (w)rite gets 2, and e(x)ecute gets 1. • The digits in the octal notation are just the sum of the allowed permissions for that class of access.

octal notation for permissions

A pipeline is a sequence of one or more commands separated by | the pipe character.

pipeline

Every user has exactly one primary group (for local users, the primary group is defined by the GID number of the group listed in the fourth field of /etc/passwd).

primary group -

This command will view all process information associated with a user.

ps au -

A common display listing (options aux) displays all processes, with columns in which users will be interested, and includes processes without a controlling terminal.

ps aux -

(-R option to recursively set permissions on the files in the entire directory tree.

recursive permissions

The command line tool redhat-support-tool can also be used to access Red Hat Customer Portal services. The Red Hat Support Tool utility. redhat-support-tool provides a text console interface to the subscription-based Red Hat Access services. The redhat-support-tool is text-based for use from any terminal or SSH connection; no graphical interface is provided. Must have access to the Internet.

redhat‐support‐tool

a relative path identifies a unique file, specifying only the path necessary to reach the file from the working directory.

relative file reference

Reload will tell the service to reload its configuration files, but keep the same process running.

reload

Restart tells it to shut down entirely, then restart. Restart will terminate the service in question and restart it; reload will only reload the configuration file

restart

Each host has a routing table, which tells it how to route traffic for particular networks. The routing table entries will list a destination network, which interface to send the traffic out, and the IP address of any intermediate router that is required to relay the message to its final destination.

routing table

lists of files installed by the specified package

rpm ‐q ‐l

Rsync tool is another way to securely copy files from one system to another. It differs from scp in that if two files or directories are similar between two systems, rync only needs to copy the differences between the systems, while scp would need to copy everything.

rsync

An improved version of syslog. The rsyslog service sorts the syslog messages by type (or facility) and priority, and writes them to persistent files in the /var/log directory.

rsyslog -

The scp command transfers files from a remote host to the local system or from the local system to a remote host. It utilizes the SSH server for authentication and encrypted data transfer.

scp

Same as Supplementary Group Membership

secondary group membership -

A service often refers to one or more daemons, but starting or stopping a service may instead make a one-time change to the state of the system, which does not involve leaving a daemon process running afterward (called oneshot).

service

A session with sftp is similar to a classic FTP session, but uses the secure authentication mechanism and encrypted data transfer of the SSH server. SFTP is a file transfer protocol similar to FTP but uses the SSH protocol as the network protocol (and benefits from leaving SSH to handle the authentication and encryption). SCP is only for transferring files, and can't do other things like list remote directories or removing files, which SFTP does.

sftp

The daemon sshd is installed and configured by default to automatically run on bootup in RHEL7.

sshd

Use ssh-keygen to create a public-private key pair. Enter the file in which to save the key (/home/student/.ssh/id_rsa) : Enter Created directory '/home/student/.ssh'

ssh‐keygen -

Preparing a bug report. Before contacting Red Hat Support, gather relevant information for a bug report. Define the problem. Be able to clearly state the problem and its symptoms. Be as specific as possible. Detail the steps which will reproduce the problem. Gather background information. Which product and version is affected? Be ready to provide relevant diagnostic information. This can include output of sosreport. For kernel problems, this could include the system's kdump crash dump or a digital photo of the kernel backtrace displayed on the monitor of a crashed system. Determine the severity level. Red Hat uses four severity levels to classify issues. Urgent and High severity problem reports should be followed by a phone call to the relevant local support center

submit bug to Red Hat

The sudo command allows a user to be permitted to run a command as root, or as another user, based on settings in the /etc/sudoers file. This command requires a user to enter their own password for authentication, not the password of the account they are trying to access. This allows an administrator to hand out fine-grained permissions to users to delegate system admin tasks, without having to hand out the root password. All commands executed using sudo are logged by default to /var/log/secure.

sudo

Users may be a member of zero or more supplementary groups. The users that are supplementary members of local groups are listed in the last field of the group's entry in the /etc/group. Supplementary group membership is used to help ensure that users have access permissions to files and other resources on the system.

supplementary group membership -

The symbolic method of changing file permissions uses letters to represent the different groups of permissions: u for user, g for group, o for other, and a for all. With the symbolic method, it is not necessary to set a complete new group of permissions. In order to accomplish this, use three symbols: + to add permissions to a set, to remove permissions from a set, and = to replace the entire set for a group of permissions. The permissions themselves are represented by a single letter: r for read, w for write, and x for execute. When using chmod to change permissions with the symbolic method, using a capital X as the permission flag with add execute permissions only I the file is a directory or already has execute set for the user, group, or other.

symbolic notation for permissions -

A standard logging system based on the Syslog protocol is built into Red Hat Enterprise Linux. syslog messages are handled by two services, systemd-journald and rsyslog. By convention, the /var/log (no "s") directory is where these logs are persistently stored.

syslog

The systemctl command is used to manage different types of system objects, called units. The list of available unit types can be displayed with systemctl -t help. The command runs as root.

systemctl -

Tab completion allows a user to quickly complete commands or file names once they have typed enough at the prompt to make it unique. If the characters typed are not unique, pressing the Tab key twice displays all commands that begin with the characters already typed.

tab completion -

Tar stands for tap archive and is one of the oldest and most common commands for creating and working with backup archives. Archiving and compressing files are useful when creating backups and transferring data across a network. The tar command can list the contents of archives or extract their files to the current system.

tar

The default port number is 22

tcp port for sshd -

In a pipeline, the tee command will cop standard input to its standard output and will also redirect its standard output to the files named as arguments to the command.

tee

a system that supports VMs while also providing other local and network services, applications, and management functions.

thick host

an expertly minimized and tuned version of Red Hat Enterprise Linux dedicated to the singular purpose of provisioning and supporting guest VMs

thin host

The timedatectl command shows an overview of the current time-related system settings, including current time, time zone, and NTP synchronization settings of the system.

timedatectl

vim is an improved version of the vi editor distributed with Linux and UNIX systems.

vim

The virsh command-line tool is an alternative to the graphical virt-manager application. Unprivileged users can use virsh in read-only mode, or with root access for full administrative functionality. The virsh command is ideal for scripting virtualization administration.

virsh

In computing, virtualization refers to the act of creating a virtual (rather than actual) version of something, including virtual computer hardware platforms, operating systems, storage devices, and computer network resources.

virtualization

Tools such as PackageKit and yum are front-end applications for rpm and can be used to install individual packages or package collections (sometimes called package groups). The yum command searches numerous repositories for packages and their dependencies so they may be installed together in an effort to alleviate dependency issues.

yum -

command will install a group which will install its mandatory and default packages and the packages they depend on

yum groupinstall

PACKAGENAME gives detailed information about a package, including the disk space needed for installation.

yum info -