RHCSA Flashcards by Stephen Amrich

How to enable port forwarding

vi /etc/sysctl.conf
	# add line
	net.ipv4.ip_forward=1
	# save file
	sysctl -p

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Disk compression

VDO

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Layered storage

Stratis

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First thing in any script

!/bin/bash

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Shell script user prompt for input

read VARIABLENAME

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default exit codes for successful and unsuccessful

exit 0 = unsuccessful exit 1 = successful

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Numerical calculations within a bash script

$((1+2))

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How to call a variable in a bash script

$VARIABLE

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How to create a local repo

create mount point (mkdir /repo)
add to /etc/fstab: /rhel8.iso /repo iso9660 defaults 0 0
mount -a

/etc/yum.repos.d
	[appstream]
	name=appstream
	enabled=1
	baseurl=file:///repo/AppStream
	gpgcheck=0

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2 things to never forget when using firewall-cmd

always run with and without permanent

always restart firewall-cmd after any changes

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How to rename a file in linux

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set time zone

timedatectl set-timezone

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How to modify boot and kernel options

/etc/default/grub (most commonly worked with, timeout time, etc, feeds changes to grub2-mkconfig)
/boot/grub2/grub.cfg (final product of grub2-mkconfig)
***Executing change to bootloader: grub2-mkconfig -o /boot/grub2/grub.cfg
grub2-set-default will change which kernal boots 0 is the first
GRUB_TIMEOUT_STYLE=hidden

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Packages required for Stratis

stratisd, stratis-cli

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Packages required for VDO

vdo, kmod-kvdo

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If having issues with stratis, how to wipe disk

wipefs -a /disk

fstab configuration for stratis

UUID /mountpoint xfs x-systemd.requires=stratisd.service

ALWAYS USE UUID
lsblk -o=UUID /dev/stratis/mypool/myfs

fstab option required for vdo

x-systemd.requires=vdo.service

Where and how to set up nfs export on nfs server

/etc/exports

/dir 10.1.1.1(rw)

exportfs -av

NFS packages

autofs, nfs-utils, nfs-server

NFS firewall services

nfs, mountd, rpc-bind

How to check available mount points for remote device

showmount -e 10.1.1.1

NFS fstab setup

option = _netdev

file system type = nfs

Samba share options

_netdev, username=user, password=password

yum install samba, yum install samba-client

NFS SEboolean

setsebool -P nfs_export_all_rw on JUST USE SETSEBOOL -P NFS TAB TAB

podman packages

podman and container-tools

User persistent container - dont forget

loginctl enable-linger USER (run from root)

location to run, and command for generating systemd podman USER file

/.config/systemd/user podman generate systemctl --files web_dev (--new for new every time) systemctl --user daemon-reload NOTE - ONLY WORKS FROM SSH OR CONSOLE, NOT SUDO OR SU

location to run, and command for generating systemd podman USER file

/etc/systemd/system | podman generate systemctl --files web_dev (--new for new every time)

Persistent mount storage on container

- v ~/web_data:/var/www/html:Z | - v and Z

Execute command within container

podman exec mycontainer cat /etc/whatever

Check container log

podman logs containername VERY IMPORTANT IF CONTAINER FAILS TO LAUNCH

Specify environment variables when creating container

-e EX: podman run -d --name mysql -e MYSQL_ROOT_PASSWORD=password

How to execute a command with results of find

find / -type f -perm 0777 -print -exec chmod 644 {} \; MOST IMPORTANT THINGS TO REMEMBER: {} = passes output of find \; ends the execute GREAT EXAMPLES IN THE MAN PAGE

How to extend xfs filesystem

xfs_growfs

How to extend ext4 filesystem

resize2fs

Settings for usermod userdel and chage

/etc/login.defs