Red Hat Certified System Administrator (RHCSA) EX200 Study Guide

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www. linuxexplor er s. com / r ed- hat - cer t if ied- syst em - adm inist r at or - r hcsa- ex200- st udy- guide/ 

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Red Hat Certified System Administrator (RHCSA) EX200 Study Guide 

Here is a study guide for the Red Hat Certified Sy stem Administrator Exam EX-200 (RHCSA). I put this together from my 

notes and followed the objectives outlined in the ex200 per the Red Hat website and illustrated how I would complete the 

requireemtns feel free to leave a comment if y ou have a different solution. 

Understand and use essential tools 

Access a shell prompt and issue commands with correct syntax. 

Open a shell by going to: 

Applications | Sy stem T ools | Konsole 

Use input-output redirection (>, >>, |, 2>, etc.). 

> Directs output to a file or device (overwrites if the file exists 

Example 

# cat /etc/testdata.txt | grep fail > failures.txt 

< Directs input from the file or device 

>> Appends output or text to a file (creates if the file doesn’t exist) 

| Redirects the output of one command to another 

Use grep and regular expressions to analyze text. 

# cat foobar.txt | grep text 

Access remote systems using ssh and VNC. 

# ssh 192.168.1.100 -l USERNAME 

# v ncv iewer 192.168.1.100 

Log in and switch users in multiuser runlevels. 

Switch user: # su 

Switch to user to root: “# su -” or “# su root” 

Archive, compress, unpack, and uncompress files using tar, star, gzip, and bzip2. 

Uncompress tar: # tar -xv f file.tar 

Unpack zipped tarball: # tar -xzv f file.tar.gz 

Uncompress gzip: # gunzip file.gz

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Uncompress bzip2: # bunzip2 file.bz2 

Uncompress star: # star -xv f=/tm p/file.star 

Create and edit text files. 

# nano T EXT FILE 

# v i T EXT FILE 

Create, delete, copy, and move files and directories. 

Delete file: # rm T EST FILE 

Copy file: # cp T EST FILE /hom e/testdir/ 

Move file # m v T EST FILE /hom e/testdir/T EST FILE.bak 

Create hard and soft links. 

Soft link: # ln -s /test/target /test/softlink 

Hard link: # ln /test/target /test/hardlink 

List, set, and change standard ugo/rwx permissions. 

# chm od ugo+rwx file.test //Ads read write execute privileges to file 

# chm od ugo-rwx file.test //Removes read write execute privileges to file 

# chm od 7 55 file.test //Ads permissions based on octal format 

Locate, read, and use system documentation including man, info, and files in /usr/share/doc. 

# m an

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# init 0 (Switches to runlevel 0 which shutdown the sy stem) 

# halt 

Reboots Com m ands 

# reboot 

# shutdown -r + 

# shutdown -r now 

# init 6 //switches to runlevel 6 which reboots the sy stem immediately 

Boot systems into different runlevels manually. 

1) Boot y our sy stem and press any key within the allotted amount of time to get to the “Grub” bootloader screen. 

2) Select y our boot “OS” and press “a” to edit the boot command 

3) Add the number of the runlevel y ou would like to use at the end of the command to boot to that runlevel 

Example: 

roroot=/dev/mapper/vg_centosvm-lv_rootrd_NO_LUKSLANG=en_US.UTF-8rd_NO_MDquiet 

SYSFONT=latarcyrheb-sun16rhgbcrashkernel=autord_LVM_LV=vg_centosvm/lv_swapKEYBOARDTYPE=pc 

KEYTABLE=usrd_LVM_LV=vg_centosvm/lv_rootrd_NO_DM1 

The “1” at the end of the boot string will boot the sy stem to runlevel 1 

Use single-user mode to gain access to a system. 

Boot the sy stem to runlevel 1 as shown above to gain super user (root) access in run level 1 

Identify CPU/memory intensive processes, adjust process priority with renice, and kill 

processes. 

Y ou can identify process with the following commands 

# ps aux 

# ps-ef 

# ps -u // shows programs running for username 

# ps -o user,com m ,pid,nice -u root //Gets the processes PID and Nice value for the root user 

top // Shows the stop processes that are using sy stem resources 

Y ou can kill processes with the following commands 

# kill -9 //hard close of the process 

# kill -15 //attempts to kill process gracefully 

# killall //kills the parent and all associated child processes 

Adjust process priorities 

# renice 

nice priorities range from -19 to 20 with -19 being the hightest priority and -20 being the lowest. 

Locate and interpret system log files. 

Y ou can find the sy stem logs in the /var/log directory . The logs can be viewed with text viwer commands such as cat, less

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and tail 

Access a virtual machine’s console. 

# v irt-v iewer REDHAT VM 

Start and stop virtual machines. 

# v irsh start REDHAT VM 

# v irsh shutdown REDHAT VM (Attempts a “graceful sy stem shutdown) 

# v irsh destroy REDHAT VM (Equivalent to turning off the sy stem with the power button unsaved data may be lost 

with this option. 

Start, stop, and check the status of network services. 

# serv ice start //example: service httpd start 

# serv ice stop 

# serv ice restart 

# serv ice status 

# checkconfig on //turns on service at boot 

# checkconfig off //turns off services at boot 

Configure local storage 

List, create, delete, and set partition type for primary, extended, and logical partitions. 

List partitions: # fdisk -l 

Delete: partitions 

1) Open the drive with: 

# fdisk /dev /sda 

2) Press “c” to turn off DOS-compatible mode and the “u” to display units in sectors. 

3) Ty pe n for a new partition. Each disk can have 4 primary partitions which are number 1-4. Partition 5 is the extended 

partition and partitions 6 – X are logical partitions. 

4) Press “w” to write the changes to the disk or “q” to exit without saving changes. 

Create and remove physical volumes, assign physical volumes to volume groups, and create and 

delete logical volumes. 

Create phy sical volume: # pv create -v /dev /sda1 /dev /sda2 

Create volume group: # v gcreate -v -s 32 VG01 /dev /sda1 /dev /sda2 

Create logical volume: # lv create -v 10g -n LV01 VG01

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# lv create -v 15g -n LV02 VG01 

Explanation: 

In order to create a logical volume the first thing that needs to be done is to format the partitions so they can be added to a 

volume group. This is done with the “pvcreate” command. 

The next step is to add the phy sical volumes to the volume group and that is done with the vgcreate command. The “-s 32” 

option define the phy sical extent size. The phy sical extent size determines the maximum size of the logical volume and the 

default phy sical extent size which 4mb. There are 65,536 phy sical extents available to a volume group with gives y ou a total 

size of 262,114mb or 256gb (4mb x 65,536 mb = 262,114mb) for the volume group. By setting the extent size to 32mb the 

maximum size of the volume group would be 2,097 ,152mb or approximately 2 teraby tes (32mb x 65,536 = 2,097 ,152mb). 

Once the volume group has been defined the next step is to add the logical volumes to the volume group. 

The volumes created in the example above will be located in /dev/VG01/LV01 and /dev/VG01/LV02 

these logical volumes can now be formatted with a file sy stem, mounted and placed in the fstab so that they are mounted 

when the sy stem boots. 

Format the Volumes 

# m kfs.ext4 /dev /VG01/LV01 

# m kfs.ext4 /dev /VG01/LV02 

Delete Volumes 

In order to remove the volumes y ou will need to run the following sequence of commands. 

# lv rem ov e /dev /VG01/LV01 

# lv rem ov e /dev /VG01/LV02 

# v grem ov e /dev /VG01 

# pv rem ov e /dev /sda1 /dev /sda2 

Create and configure LUKS-encrypted partitions and logical volumes to prompt for password 

and mount a decrypted file system at boot. 

The following procedure assumes that the dm_cry pt module has been loaded. For a more detailed explanation please see 

# cry ptsetup luksForm at /dev /sda1 //formats the drive and prompts y ou to create a passphrase 

# cry ptsetup luksOpen /dev /sda1 luks01 //opens drive /dev/sda1 and maps it to /dev/mapper/luks01 

# m kfs.ext4 /dev /m apper/luks01 //formats the volume with the ext4 file sy stem. 

Now that the LUKS-encry pted volume has been created and formatted it can be added to the boot process. 

Create an “/etc/cry pttab” file. 

Add the following line to the file and save it: 

luks01 /dev /sda1 

the cry pttab file will attempt to open the encry pted volume at boot and will prompt y ou for a password. If the file is 

successfully opened its mapped to /dev/mapper/luks01

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next add the mapped volume to the fstab 

/dev/mapper/luks01/LUKSext4defaults12 

See this article for a more detailed explanation on luks encry ption 

http://www.linuxexplorers.com/2012/03/how-to-configure-a-luks-encry pted-partition-in-red-hat-enterprise-linux-rhel- 

rhcsa-objective/ 

Configure systems to mount file systems at boot by Universally Unique ID (UUID) or label. 

Add the following line to the /etc/fstab 

UUID=6a235116-5447-4c68-b14a-644196d76902/homeext4defaults12 

Add new partitions and logical volumes, and swap to a system non-destructively. 

Y ou need to be careful when editing the /etc/cry pttab and /etc/fstab files. Errors could cause y ou to have boot problems 

which my cost valuable time to troubleshoot during the exam. Double check y our work and make backup copies of the files 

in case y ou make a mistake. 

Create and configure file systems 

Create, mount, unmount, and use ext2, ext3, and ext4 file systems. 

Create file sy stems 

# ext4: m kfs.ext4 /dev /sda1 



# m kswap /dev /sda3 //makeswap partition 

Mount file sy stem: 

# m ount /dev /sda1 /m ountpoint 

# m ount -a //mounts all file sy stems in the /etc/fstab file 

Unmount file sy stem: 

# um ount /m ountpoint 

Mount, unmount, and use LUKS-encrypted file systems. 

LUKS filesy stems need to be “opened” before they can be mounted once opened it can be mounted with a command such as: 

#m ount /dev /m apper/LUKS /hom e/luks_m ount 

Mount and unmount CIFS and NFS network file systems. 

Mount NFS Volume: 

# m ount 192.168.1.67 :/hom e /hom e/nfs_local 

Mount CFS Volume

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# m ount -t cifs -o guest //192.168.1.7 0/Share /hom e/win_m ount 

Configure systems to mount ext4, LUKS-encrypted, and network file systems automatically. 

/etc/fstab entries 

/dev/mapper/LUKSext4defaults12 

/dev/sda1/homeext4defaults12 

//192.168.1.70/Share/home/win_mountcifsguest,_netdev00 

192.168.1.67:/home/home/nfs_localnfsdefaults00 

Extend existing unencrypted ext4-formatted logical volumes. 

# v gextend VG01 /dev /sdb1 //adds partition to volume group VG01 

# lv extend -L +5g /dev /VG01/LV011 //adds 5gigs to logical volume LV01 

# resize2fs -p /dev /VG01/LV01 //resizes the filesy stem 

Create and configure set-GID directories for collaboration. 

Create a directory to be shared by a group 

# m kdir /hom e/topsecret 

# chgrp -R security /hom e/topsecret //changes group owner of the folder to security 

# chm od 27 55 /hom e/topsecret // Adds the GUID bit to the directory 

# chm od g+s /hom e/topsecret //Adds the GUID bit to the directory 

Create and manage Access Control Lists (ACLs). 

# setfacl -m u:boss:rwx /hom e/bonus_pay outs.txt //add the user boss to the file 

# setfacl -x u:boss /hom e/bonus_pay outs.txt //remove the user boss from the file 

# setfacl -b /hom e/bouns_pay outs.txt //removes the acl settings from the file 

# getfacl /hom e/bonus_pay outs.txt // lists the acl settings for the directory 

Diagnose and correct file permission problems. 

Deploy, configure, and maintain systems 

Configure networking and hostname resolution statically or dy namically . 

DHCP Configuration 

nano/etc/sysconfig/network-scripts/ifcfg-eth0 

DEVICE="eth0" 

BOOTPROTO="dhcp" 

HWADDR="00:16:D4:39:5B:6F" 

NM_CONTROLLED="yes" 

ONBOOT="yes"

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StaticIP 

DEVICE="eth0" 

IPADDR=192.168.1.100 

NETMASK=255.255.255.0 

HWADDR="00:16:D4:39:5B:6F" 

NM_CONTROLLED="yes" 

ONBOOT="yes" 

DNS1=192.168.1.254 

/etc/sysconfig/network 

NETWORKING=yes 

HOSTNAME=RH_PC.com 

GATEWAY=192.168.1.254 

#servicenetworkrestart 

Schedule tasks using cron 

Username = tigerwoods 

# crontab -e 

sample entry 

default entries must edited with the “vi” editor 

*/2 * * * * touch /hom e/tigerwoods/win_m asters{1..10}.txt 

this entry creates the files “win_masters1.txt, win_masters2.txt through win_masters10.txt 

Sy stem crontab 

/etc/crontab 

The sy stem crontab consists cron jobs for “sy stem” processes. For example scripts that clean space from users home 

directories. 

Configure systems to boot into a specific runlevel automatically. 

Edit the /etc/inittab and specify the runlevel or exit the etc/grub.conf file 

Install Red Hat Enterprise Linux automatically using Kickstart. 

Install a VM with kickstart 

#virt-install-nVMGUEST01-r2048–vcpus=1-l/home/RHINSTALL--disk 

path=/home/VM/VMGUEST01.img,size=50-x“ks=/home/ks.cfg” 

Options 

-n Name of the VM Guest 

-r Amount of RAM in MB 

–v cpus Number of CPUs to be used 

-l location of the install files 

–disk d efine the location for the disk file and its size. The size is in GB

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-x location of the kickstart file 

This can also be done via virt-manager GUI 

Configure a physical machine to host virtual guests. 

# y um -y groupinstall Virtualization 

# y um -y groupinstall “Virtualization Client” 

Install Red Hat Enterprise Linux systems as virtual guests. 

Install virtual guests via the virt-manager console or via the virt-install command 

Configure systems to launch virtual machines at boot. 

Configure this through the virt-manager or virt-viewer console or with the command 

# v irsh autostart 

Configure network services to start automatically at boot 

# chkconfig on 

Configure a system to run a default configuration HTTP server. 

# y um -y install httpd 

# serv ice httpd start 

# chkconfig httpd on 

Configure a system to run a default configuration FTP server. 

# y um -y install v sftpd 

# serv ice v sftpd start 

# chkconfig v sftpd on 

Install and update software packages from Red Hat Network, a remote repository, or from the 

local file system. 

Use y um to update and install packages.

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Update the kernel package appropriately to ensure a bootable system. 

Install the new kernel side by side and edit the grub bootloader 

# y um -y install kernel //installs newest kernel and modifies grub to boot with new kernel 

Modify the system bootloader. 

Edit the /etc/grub.conf file 

Manage users and groups 

Create, delete, and modify local user accounts. 

useradd 

userm od -a -G //add’s user to a group 

Change passwords and adjust password aging for local user accounts. 

passwd 

# chage -M 30 tigerwoods //sets the password to expire evert 30 day s for user tigerwoods 

# chage -E “2012-05-31″ tigerwoods //sets the password to expire on 5/31/2012 for user tigerwoods 

Create, delete, and modify local groups and group memberships. 

Manually edit the /etc/group 

file to add groups 

groupadd 

groupmod 

gpasswd 

Configure a system to use an existing LDAP directory service for user and group information. 

Manage security 

Configure firewall settings using system-config-firewall or iptables. 

Y ou can open or close ports in the firewall by editing the /etc/sy sconfig/iptables file 

Set enforcing and permissive modes for SELinux. 

Use sestatus to determine if SELinux is in enforcing or permissive mode. 

This can be done by editing the /etc/sy sconfig/selinux file or with the following commands 

# setenforce 1 //sets SELinux to run in enforcing mode 

# setenforce 0 //sets SELinux to run in permissive move#

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List and identify SELinux file and process context. 

# ls -Z //lists SELinux context for directories 

# ps -ef -Z //lists SELinux context for processes 

# id -Z //List SELinux contexts for users 

# cp -Z // directory copy SELinux context for files. If not specified the file inherits the contex for the 

destination directory 

Restore default file contexts. 

# restorecon 

Use boolean settings to modify system SELinux settings. 

# getsebool -a //lists all SELinux boolean settings 

# setsebool -p =1 //turns on SELinux boolean setting 

Example: 

#setsebool -P sam ba_run_unconfined=1 

settings can also be toggled with 

# togglesebool 

SELinux booleans can also be configured with the sy stem-config-selinux 

Diagnose and address routine SELinux policy violations. 

# sealert -a /v ar/log/audit/audit.log

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