RHCSA EX200

Red Hat Certified System Administrator

Important Informations

Example Practice Questions

Configure the network

#From console of serverb.lab.example.com
hostnamectl set-hostname serverb.lab.example.com #Sets FQDN
hostname #To verify hostname
nmcli connection #Shows all connection interfaces
nmcli connection modify "wired_connection_name" ipv4.addresses 172.25.250.11/24 ipv4.gateway 172.25.250.254 ipv4.dns 172.25.250.254 ipv4.method static
#Don't forget the netmask /24 means 255.255.255.0
nmcli connection up "wired_connection_name"
ping 172.25.250.11 #To verify if everything is correct
reboot

Create a repository

#Use SSH and [email protected]
vi /etc/yum.repos.d/new.repo #Extension is always repo
[1]
name=app
baseurl=http://classroom.example.com/content/rhel8.0/x86_64/dvd/AppStream
enable=1
gpgcheck=0
[2]
name=base
baseurl=http://classroom.example.com/content/rhel8.0/x86_64/dvd/BaseOS
enable=1
gpgcheck=0

yum clean all #Cleans all cache repos
yum repolist all #Shows all the repo list
yum install vim -y #Verify

Configure the Selinux

semanage port -l | grep http #Check if port is used by any service
semanage port -a -t http_port_t -p tcp 82 #Add service to port
firewall-cmd --permanent --add-port=82/tcp #Add entry to firewall
firewall-cmd --reload #Reloads the firewall for changes to apply
firewall-cmd --list-all #Lists the firewall allows
yum install httpd -y #Install Apache
# Insert the below content
systemctl start httpd #Start the apache service
systemctl enable httpd # Enable the apache service

vim /etc/httpd/conf/httpd.conf #Open apache conf file
#Add a webpage as virtual host
<virtualhost 172.25.250.11:82>
servername serverb.lab.example.com
documentRoot /var/www/html
</virtualhost>
:wq #Saves the file in vim

httpd -t #Checks for syntax errors in config file
systemctl restart httpd #Restart the apache services
ls /var/www/html #Check files for webserver root directory
curl http://172.25.250.11:82/filename #verify

Create the following users, groups and group memberships

groupadd admin # Create group
useradd harry -G admin #User create with group
useradd -G admin natasha #User create with group
useradd -s /sbin/nologin sarah # User create with no shell access
passwd --stdin harry #Create password for harry
id harry #Verify
cat /etc/groups #Verify

Create a collaborative directory /common/admin with the following characteristics

mkdir -p /common/admin #Create the directory
chgrp admin /common/admin #Change ownership to admin
chmod 770 /common/admin # Change permission
chmod g+s /common/admin #Future permission to group
ls -ld /common/admin #verify
su harry #login with harry as he is admin
#create a file inside the folder and verify
logout

Configure autofs to automount the home directories of production5 domain users.

yum install autofs #Install autofs
systemctl start autofs #Start the service
systemctl enable autofs # Enable service at system reboot
getent passwd production5 # Shows user home directory info

vim /etc/auto.misc #Edit autofs conf
production5    -rw,soft,intr servera.lab.example.com:/home/production5
:wq

systemctl restart autofs #Restart autofs after conf change
su production5 #Login as the user
#Create a file inside the home directory of production5
logout

Set a Cron job for harry on 12.30 at noon print /bin/echo on "hello".

crontab -eu harry #Open crontab to edit
30 12 * * * /bin/echo "hello"

cat /etc/crontab #Check for the changes in crontab
crontab -lu harry #verify

Configure Acl permission

setfacl -m u:harry:rw /var/tmp/fstab #Set ACL for harry
setfacl -m u:natasha:--- /var/tmp/fstab #Set facl for natasha
getfacl /var/tmp/fstab  /var/tmp/fstab #Verify

Configure the NTP

vim /etc/chrony.conf #Open NTP configuration
#Remove the other default server
server classroom.example.com iburst #Add this line

systemctl restart chronyd.service #Restart the server
chronyd sources #verify

Locate the Files

find / -user sarah -type f -exec cp{} /root/find.user \;
ls -al /root/find.user #verify

Find the string

grep "home" /etc/passwd > /root/search.txt

Create a user account

useradd -u 1326 alies 

Create an archieve file

tar -zcvf /root/test.tar.gz /var/tmp
#If file ext is gz=z and bz2=j

Set the Permission

su - natasha #change the user in shell
umask #check current umask

vim .bash_profile #Open bash conf
umask 277 #Set custom umask

source .bash_profile #Source new conf
mkdir folder1 #Test1
touch file1.txt #Test2
logout 

Password Expire Date

vim /etc/login.defs  #Open configuration file
PASS_MAX_DAYS 20     # Number is in days

Assign Sudo Privilege

vim /etc/sudoers  #Open the config file
#for user 
admin ALL=(ALL) NOPASSWD:ALL
#For Groups
%admin ALL=(ALL) NOPASSWD:ALL
#Save with
:wq!

Login Text Message

su - alice  # Change user to alice

vim .bash_profile  #Open bash profile
RHCSA="Welcome to Redhat"
export RHCSA #Export the variable to use
echo $RHCSA  #This will echo at the time of login

source .bash_profile #Apply the bash profile changes
logout 
su -alice #After login you will get the text

Create the script file

mkdir /root/myfiles
vim mysearch
#! /bin/bash
find /usr/share -type f -size -1M -exec cp{} /root/myfiles \; #Find the files
 
chmod +x mysearch #Give execution permission to script
sh mysearch # Run the script

Password Break

#Reboot the system and press e when grub comes up to edit grub
# Add rd.break at the last of the line started with Linux
#save and start the machine to enter maintainence mode
mount -o remount,rw /sysroot
chroot /sysroot
passwd --stdin root
#Enter the password
touch /.autorelabel
exit
exit
#Take ssh of that server with new password

Create Repository File

vi /etc/yum.repos.d/new.repo #Extension is always repo
[1]
name=app
baseurl=http://classroom.example.com/content/rhel8.0/x86_64/dvd/AppStream
enable=1
gpgcheck=0
[2]
name=base
baseurl=http://classroom.example.com/content/rhel8.0/x86_64/dvd/BaseOS
enable=1
gpgcheck=0

yum clean all #Cleans all cache repos
yum repolist all #Shows all the repo list
yum install vim -y #Verify

Create a swap partition 512MB size

lsblk # Shows all devices
fdisk /dev/vdb #Open fdisk to configure device and partitions
n
p
Enter
Enter
+512M
t
L
82
p
w

udevadm settle on partprobe # Implies that you want to wait for all pending udev events to be completed before running the partprobe command
lsblk 
mkswap /dev/vdb1 #Format the partition as swap
blkid #Get the ID of attatched devices and partitions
vim /etc/fstab #Add entry to mount at boot
/dev/vdb1  swap swap defaults 0 0

free -h #Check total swap
swapon -a #mount the new swap
free -h #Verify the total swap

LVM and LVG

fdisk /dev/vdb #Open to make partitions
n
p
Enter
Enter
+2G
t,2
8e
vgcreate -s 8M datastore /dev/vdb2 #Create the vg
lvcreate -l 50 -n database datastore #Create the lv within vg
lsblk #verify the configuration
mkfs.ext3 /dev/datastore/database #Format the logical volume
blkid
mkdir /mnt/database
vim /etc/fstab
/dev/datastore/database /mnt/database ext3 defaults 0 0 #Add to mount on boot

mount -a #Mount the partition
df -hT #See mounted disks

VDO

yum install vdo -y #Install vdo
systemctl start vdo #Start vdo service
systemctl enable vdo #Start vdo with system boot
vdo create --name=vectra --device=/dev/vdb --vdoLogicalSize=50G #Create vdo logical partition
vdo list  #Lists all vdo
mkfs.xfs /dev/mapper/vectra #Format the VDO in xfs(default if not mentioned format)
blkid
mkdir /test
vim /etc/fstab #Add in fstab to mount at system boot
/dev/mapper/vectra /test xfs defaults,x-systemd.requires=vdo.service 0 0

mount -a #Mount now
df -hT #See mounted disks

#Login in console as root with password
mount -o remount,rw /
vim /etc/fstab
# Comment the vdo line and reboot

LV Extend

df -hT
lvextend -l 100 -r /dev/mapper/datastore-database # Size=100*VGSize=100*8MB
#If you want to directly use size use -L 600M

Tuned

yum install tuned
systemctl start tuned
systemctl enable tuned
tuned-adm recommend
tuned-adm profile profile-name
tuned-adm active
tuned-adm list
systemctl restart tuned

Create the container as system startup service

Configure the Container as persistent storage and create logs for container

sh root@serverc
id paradise
useradd paradise
passwd --stdin paradise
ssh paradise@serverc #Keep the root ssh session in another tab
mkdir ~/container_journal 

#Execute below in root tab
ls /var/log
vim /etc/systemd/journal.conf
storage=persistent

systemctl restart systemd_journald.service
ls /var/log/journal
cp /var/log/journal/<press Tab>/*.journal /home/paradise/container_journal/
ls /home/paradise/container_journal

#Execute in paradise user
podman login
podman search rsyslog #Take the rhel7/rsyslog(The 1st one)
podman pull registry.lab.example.com/rhel8/rsyslog #According the image it changes
podman images
podman run -d --name logserver -v /home/paradise/container_journal:/var/log/journal:Z registry.lab.example.com/rhel7/rsyslog #URL may vary according to image
podman ps
mkdir -p ~/.config/systemd/user
cd ~/.config/systemd/user
ls
podman generate systemd --name logserver --new --files
ls
podman stop logserver
podman run logserver
podman ps
systemctl --user daemon-reload
systemctl --user start container-logserver.service
systemctl --user enable container-logserver.service
podman ps

#Execute as root
loginctl show-user paradise #Check if linger=no is set
loginctl enable-linger paradise
loginctl show-user paradise

#Execute as paradise
podman ps