RHCSA Objectives ANSWERS

Understand and use essential tools

·         Access a shell prompt and issue commands with correct syntax.

A: Applications -> system tools -> terminal

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

A: 1 > stdout 2> stnderr > filename < stdin (both stdoutAndstderr >filename 2>&1

·         Use grep and regular expressions to analyze text.

A: grep word filename, grep -v (do not). grep -v ^# filename

·         Access remote systems using ssh and VNC.

A: ssh root@iptaddress; yum install tigervnc-server(server) (client - tigervnc) 

·         Log in and switch users in multiuser runlevels.

·         A: su - username (su -)

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

A: tar –czvf newtar.tar.gz originfile (j – bz2), untar = tar –x(j)zvf newtar.tar.gz, star –c f=newname.star filename, sar –xattr f=backup.star sat.doc

·         Create and edit text files.

A: vim, touch, cat-read, ls –la, less

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

A: touch, rm (-rf), cp (-rp), mv

·         Create hard and soft links.

A: ln –s /fullpath source/ fulpath ; ln sourcefile filename

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

A: ls –l, ll, chmod, r = 4, w=2, x=1

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

A: rpm –qd service, locate, find, grep less

Note: Red Hat may use applications during the exam that are not included in Red Hat Enterprise Linux for the purpose of evaluating candidate's abilities to meet this objective.

Operate running systems

·         Boot, reboot, and shut down a system normally.

A: init 0, init 6, shutdown –r now, shutdown –h now (+10), reboot

·         Boot systems into different runlevels manually.

A: init 1,2,3, telinit 1,2,3

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

A: space bar, grub menu edit, kernel append 1 (passwd)

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

A: top, ps, pstree, ps –ef, top –p pidnumber, sar –A, lsof –c; nice –n –p, renice, inside top (r option) to renice, kill -9(-15) pidnumber, killall name, pkill -9 (-15) or no number; ps –aux | grep –w Z (zombie process)

·         Locate and interpret system log files.

A: less, more, tail (-f),  dmesg, sealert –a /var/log/audit/audit.log

·         Access a virtual machine's console.

A: Applications->system tools->virt-manager, virt-view domain

·         Start and stop virtual machines.

A: virsh shutdown (destroy) domain, virsh start domain, virsh list –all,

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

A: /etc/init.d/network status (stop, start, restart)

Configure local storage

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

A: fdisk –l, n, d, p, e: pvs, vgs,lvs, lvdisplay, pvcreate(vg,lv) lvremove

·         Create and remove physical volumes, assign physical volumes to volume groups, and create and delete logical Volumes.

A: pvcreate, vgcreate, vgremove, pvremove

·         Create and configure LUKS-encrypted partitions and logical volumes to prompt for password and mount a decrypted file system at boot.

A: crypsetup –y –v luksFormat /dev/mapper/balo1

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

# blkid

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

A: pvcreate,vgextend, lvresize –r, mkswap –L Labelname, swapon Labelname

Create and configure file systems

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

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

·         Mount and unmount CIFS and NFS network file systems.

A: mount –t cifs //serverip/shareolder /mnt

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

·         Extend existing unencrypted ext4-formatted logical volumes.

·         Create and configure set-GID directories for collaboration.

A: chmod 2070 /home/group

·         Create and manage Access Control Lists (ACLs).

A: add acl by defaults in /etc/fstab, setfacl –m u:user:rwx /file (-x remove, -b remove all the acl)

·         Diagnose and correct file permission problems.

A: ls –l, lsattr, chattr +

Deploy, configure, and maintain systems

·         Configure networking and hostname resolution statically or dynamically.

A: /etc/sysconfig/network-scripts/ifcfg-eth0

·         Schedule tasks using cron.

A: crontab –e, crontab –l

·         Configure systems to boot into a specific runlevel automatically.

A: /etc/inittab

·         Install Red Hat Enterprise Linux automatically using Kickstart.

A: system-config-kickstart; -x ks=, linux ks=http:file

·         Configure a physical machine to host virtual guests.

A: yum groupinstall “Virtualization”; yum groupinstall “Virtualization Platform”; yum groupinstall “Virtualization Client”

·         Install Red Hat Enterprise Linux systems as virtual guests.

A: virt-install, or Applications->System Tools-> Virt-manager->create new

·         Configure systems to launch virtual machines at boot.

A: virsh autostart domainname

·         Configure network services to start automatically at boot.

A: ifcfg-eth0 -> ONBOOT=yes

·         Configure a system to run a default configuration HTTP server.

A: yum groupinstall “Web Server” –y; service httpd start, chkconfig httpd on, open port80.

·         Configure a system to run a default configuration FTP server.

A: yum install vsftpd –y; service vsftpd start, chkconfig vsftpd on, open port 20 and 21

·         Configure a system to use time services.

A: yum install ntp –y, vim /etc/ntp.conf

·         Install and update software packages from Red Hat Network, a remote repository, or from the local file system.

A: vim /etc/yum.repos.d/file.repo, [name],name=, baseurl=http://server/model/os/$basearch; yum clean all, yum repolist all, yum install –disablerepo package

·         Update the kernel package appropriately to ensure a bootable system.

A: yum install kernel

·         Modify the system bootloader.

A: vim /boot/grub/grub.conf

Manage users and groups

·         Create, delete, and modify local user accounts.

A: useradd, userdel (-r), usermod, usermod –aG team user

·         Change passwords and adjust password aging for local user accounts.

A: passwd; chage –E mm/dd/yyyy user; chage –l user

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

A: groupadd, groupmod, groupdel,

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

A: GUI mode -> Adminstration

Manage security

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

A: system-config-firewall

·         Set enforcing and permissive modes for SELinux.

A: setenforce 1 or 0 or /etc/selinux/config

·         List and identify SELinux file and process context.

A: ls –Z or for dir – ls –Zd, ps –eZ |grep processname

·         Restore default file contexts.

A: restorecon -R

·         Use boolean settings to modify system SELinux settings.

A: semanage boolean –l, setsebool –P boolean on/off

·         Diagnose and address routine SELinux policy violations

A: yum install policycoreutils-gui setroubleshoot, sealert –a /var/log/audit/audit.log