{{tag>[rhel7 certification]}}


=====RHCSA v7 EX200 objectives (20160323)=====
Some notes on the EX200 exam.

  * [[https://www.redhat.com/en/services/training/ex200-red-hat-certified-system-administrator-rhcsa-exam]]

  * You cannot shrink Xfs (you can shrink ext4).
  * Change root password in single user mode is a different procedure (rd.break).
  * ''makewhatis'' is gone, use ''mandb''.

==== - Understand and use essential tools====
=== - Access a shell prompt and issue commands with correct syntax===
  * Use SSH or the console to log in. You can try tab-complete to find commands or the locate, find, etc,  command. Use the man-pages or options:<code>-h -x -? --help</code>

=== - Use input-output redirection (>, >>, |, 2>, etc.)===
  * ''>'' Redirect output, target is truncated before writing starts.
  * ''>>'' Redirect output, append to target.
  * ''|'' Connect standard output to standard input (a pipe).
  * ''2>'' redirect stderr.
=== - Use grep and regular expressions to analyze text===
  * Grep all lines without starting with an ''#'' or empty space: <code>grep ^[^#] file</code>
  * Interpret PATTERN as a list of fixed string: <code>grep -F <string> <file>
#or
fgrep</code>
  * Invert match ''grep -v''.
=== - Access remote systems using ssh===
  * SSH client configuration in ''~/.ssh/config''.
  * Verbose logging: ''ssh -vvv <host>''.
  * Tunnel: ''ssh -L8080:host:80 host''.
  * Enable X11 forwarding: ''ssh -X <host''.
=== - Log in and switch users in multiuser targets===
  * Switch to root: ''sudo -i'' or ''sudo su -''.
  * Edit sudoers: ''visudo'' or add to ''/etc/sudoers.d/''.
  * Swith to user with nologin shell: ''su -s /bin/bash user''.
=== - Archive, compress, unpack, and uncompress files using tar, star, gzip, and bzip2===
  * TAR
    * Create: ''c''.
    * Verbose: ''v''.
    * File: ''f''.
    * Gzip: ''z''.
    * Bzip2: ''j''.
  * GZIP: ''gzip <file>'', ''gunzip <file>''.
=== - Create and edit text files===
  * Create 'text' file: ''vi'' or ''vim''.
  * Redirect output (overwrite) to file: ''echo "hi" > filename''.
=== - Create, delete, copy, and move files and directories===
  * Create empty file: ''touch''.
  * Remove file: ''rm file''.
    * Force: ''-f''.
    * Recursive: ''-r''.
  * Copy: ''cp source destination''.
    * Preserve mode, owner and timestamps: ''-p''.
    * Recursive ''-r''.
  * Move: ''mv source destination''
=== - Create hard and soft links===
  * Create hard link: ''ln target link-name''.
  * Create soft link: ''ln -s target link-name''.
  * Show inode number (for hard links): ''ls -i''.
=== - List, set, and change standard ugo/rwx permissions===
  * List permissions: ''ls -l'' or ''stat file''.
  * Set permissions: ''chmod 755'' or ''chmod o+rw'' etc.
  * Change owner: ''chown user:group target''.
=== - Locate, read, and use system documentation including man, info, and files in /usr/share/doc===
  * Man pages: ''man command''.
  * Search all man pages: ''man -k command''.
  * Search for text in all man pages: ''man -K text''.
  * Info pages: ''info command''.
  * Read documentation in ''/usr/share/doc'' directories.
==== - Operate running systems====
=== - Boot, reboot, and shut down a system normally===
  * Boot: turn on server or virtual machine.
  * Reboot: ''reboot'' or ''shutdown -r now'' or ''systemctl isolate reboot.target''
  * Shutdown: ''shutdown -h now'' or ''systemctl isolate poweroff.target''.
=== - Boot systems into different targets manually===
  * Show default target: ''systemctl get-default'' or ''ls -lh /etc/systemd/system/default.target''
  * List all tartgets:<code>systemctl list-units --type target --all</code>
  * Rescue mode: ''systemctl rescue''.
  * Emergency mode: ''systemctl emergency''
=== - Interrupt the boot process in order to gain access to a system===
  * In grub boot menu, select desired kernel, press 'e', edit the kernel line and append (ctrl-e) the word ''single''. Boot the system.
  * If you need to change the root password:<code>
# press 'e' in the grub menu, 
# change add: rd.break enforcing=0
# press ctrl-x
mount -o remount,rw /sysroot
chroot /sysroot
passwd root
touch /.autorelabel
mount -o remount,ro /
exit
exit
</code>



=== - Identify CPU/memory intensive processes, adjust process priority with renice, and kill processes===
  * Identify CPU/Memory intensive processes with: ''top''.
  * Adjust priority with ''nice command -n <number -20 - 19>'' and ''renice -n <priority> <PID>''. A higher number is more nice. 
  * Show nice level of processes: ''ps -efl''.
=== - Locate and interpret system log files and journals===
  * Query the systemd journal: ''journalctl''.
    * Follow: ''-f''.
    * Augment log lines with explanation texts: ''-x''.
    * Show all logs from specified service: ''journalctl /usr/sbin/sshd''.
=== - Access a virtual machine's console===
  * ''virsh console <vm>''.
=== - Start and stop virtual machines===
  * ''virsh stop <vm>''.
  * ''virsh start <vm>''.
=== - Start, stop, and check the status of network services===
  * Show connections: ''nmcli c show''
  * Up: ''nmcli c up eth0''
  * Down: ''nmcli c down eth0''
  * Edit: ''nmcli c edit eth0''
=== - Securely transfer files between systems===
  * SCP: ''scp <file> <target-host>''
  * sftp

==== - Configure local storage====
=== - List, create, delete partitions on MBR and GPT disks===
  * List partitions: ''fdisk -l /dev/vda'' or ''fdisk /dev/vda''
  * Delete and edit with: ''fdisk'' or ''parted''

=== - Create and remove physical volumes, assign physical volumes to volume groups, and create and delete logical volumes===
  * Create PV: ''pvcreate /dev/vda2''.
  * Assign to VG: ''vgextend <VGname> <PhysicalDevicePath>''.
  * Create LV: ''lvcreate -L 5GB -n <lvname> <vgname>''.
  * Remove LV: ''lvremove /dev/<vgname>/<lvname>''.

=== - Configure systems to mount file systems at boot by Universally Unique ID (UUID) or label===
  * Show UUID's: ''blkid''.
  * Add UUID to /etc/fstab: ''UUID=7c2eaf53-ae5b-4b81-a539-b5f5d34c60c5 /boot                   xfs     defaults,noatime 0 0''
  * Label a device: ''e2label /dev/mapper/testV testlv''
  * In ''/etc/fstab'' use: ''LABEL=testlv '' as device.

=== - Add new partitions and logical volumes, and swap to a system non-destructively===
  * For Partitions and LVs, see above. 
  * Add SWAP:
    * fdisk set partition to SWAP
    * ''partx -a /dev/vdc''.
    * ''partprobe''.
    * ''mkswap /dev/vdc1''.
    * ''swapon -v /dev/vdc1''.
    * Show swap: ''swapon -s''.
  * Add swap file as an example:
    * Create 512MB file: ''dd if=/dev/zero of=/var/tmp/swapfile1 bs=1024 count=524288''.
    * Change owner and mode: ''chown root:root /var/tmp/swapfile1'' ''chmod 0600 /var/tmp/swapfile1''.
    * Make swap: ''mkswap /var/tmp/swapfile1''.
    * Activate swap: ''swapon /var/tmp/swapfile1''.
    * Show swap: ''swapon -s''.


==== - Create and configure file systems====
=== - Create, mount, unmount, and use vfat, ext4, and xfs file systems===
  * Create file system: ''mkfs.<fstype>''.
  * Mount file system: ''mount -t <vfstype> <device> <directory>''.

=== - Mount and unmount CIFS and NFS network file systems===
  * Show NFS exports: ''showmount -e''.
  * Mount NFS: ''mount <server>:mountoint <directory>''.
  * Show SMB shares: ''smbclient -L diskstation -U user''.
  * Mount CIFS: <code>mount -t cifs //server/share /mnt -o user=username</code>
=== - Extend existing logical volumes===
  * Check spave available in PV and VG: ''pvs'', ''vgs''
  * Resize LV: ''lvresize -r -l+100%FREE <lvname>''.
=== - Create and configure set-GID directories for collaboration===
  * An SGID on directory will have new files and directories have its group set to the group.
  * Create team group, change group of directory (chown). 
  * Add SGID: ''chmod g+s /data/team''.
  * Allow write: ''chmod g+w /data/team''.
  * Enable users to see files from others, but no delete (like /tmp): ''chmod +t /data/team''
=== - Create and manage Access Control Lists (ACLs)===
  * Check if filesystem is mounted with acl option: ''mount''. But ext4 is already acl aware.
  * If not mounted with acl option, add it to fstab and remount, or: ''mount -o remount /var''
  * If an ACL is present, then ''ls -l'' will show a plus sign next to the rwx modes.
  * Set ACL: ''setfacl -m u:user:rw- <filename>''

=== - Diagnose and correct file permission problems===
  * ''ls -l'', ''getfacl'', ''lsattr''.
  * ''chmod'', ''chown'', ''setfacl'', ''chattr''.
==== - Deploy, configure, and maintain systems====
=== - Configure networking and hostname resolution statically or dynamically===
  * Edit network configuration (including DNS servers): ''nmcli''
  * Static hostname resolution in ''/etc/hosts''.
  * Set own hostname: ''hostnamectl set-hostname <hostname>''.
=== - Schedule tasks using at and cron===
  * Add crontabs in ''/etc/crontab'' and below directories ''/etc/cron.d'', ''/etc/cron.daily'', etc.
  * Scheduling: ''min hour daymonth month dayweek(0=sun)''
    * /2 = every 2 hours
    * /5 = every 5 minutes
    * ''30 4 1,15 * 5'' would cause a command to be run at 4:30 am on the 1st and 15th of each month, plus every Friday.
=== - Start and stop services and configure services to start automatically at boot===
  * List services:<code>systemctl list-unit-files --type service</code>
  * Start: ''systemctl start sshd.service''.
  * Stop: ''systemctl stop sshd.service''.
  * Restart: ''systemctl restart sshd.service''.
  * Start at boot: ''systemctl enable sshd.service''.
  * Disable start at boot: ''systemctl disable sshd.service''.
=== - Configure systems to boot into a specific target automatically===
  * List targets: <code>systemctl list-units --type target --all</code>
  * Show default target:<code>systemctl get-default
#or
ls -lh /etc/systemd/system/default.target</code>
  * Set default target: <code>systemctl get-default multi-user.target</code>

=== - Install Red Hat Enterprise Linux automatically using Kickstart===
  * Install webserver to service the Kickstart file: ''yum -y install httpd system-config-kickstart''.
  * rsync CDROM to ''/var/www/html/pub''
  * At boot edit kernel line, add: ''ks=http://192.168.122.35/ks.cfg''
=== - Configure a physical machine to host virtual guests===
  * Install virtualization packages: ''yum groupinstall Virtualization "Virtualization Tools"''.
=== - Install Red Hat Enterprise Linux systems as virtual guests===
  * Use ''virsh'' or ''virt-manager''.
=== - Configure systems to launch virtual machines at boot===
  * Configure: ''virsh autostart <vm>''
=== - Configure network services to start automatically at boot===
  * See ''nmcli'' above.
=== - Configure a system to use time services===
  * Use NTPd or Chrony.
=== - Install and update software packages from Red Hat Network, a remote repository, or from the local file system===
  * Use repo files in /etc/yum.repos.d or RedHat Satellite.
  * ''yum-config-manager''
=== - Update the kernel package appropriately to ensure a bootable system===
  * Install new kernel: ''rpm'' or ''yum''.
  * Check: ''/etc/default/grub''.
=== - Modify the system bootloader===
  * Edit: ''/etc/default/grub''.
  * Generate the new config: ''grub2-mkconfig -o /boot/grub2/grub.cfg''
  * ''grub2-editenv list''
  * ''grub2-set-default''
==== - Manage users and groups====

=== - Create, delete, and modify local user accounts===
  * Create: ''useradd''.
  * Modify: ''usermod''.
  * Delete: ''userdel''.

=== - Change passwords and adjust password aging for local user accounts===
  * Change password: ''passwd''.
  * Change age: ''chage''.
  * List age: ''chage -l <username>''.

=== - Create, delete, and modify local groups and group memberships===
  * Create: ''groupadd''.
  * Modify: ''groupmod''.
  * Delete: ''groupdel''.

=== - Configure a system to use an existing authentication service for user and group information===
  * Configure ''SSSd'' or ''PAM-LDAP''.
  * Use ''authconfig-tui''.

==== - Manage security====

=== - Configure firewall settings using firewall-config, firewall-cmd, or iptables===
  * Get info on active zones: ''firewall-cmd --get-active-zones''.
  * Get info on specific zone: ''firewall-cmd --zone public --list-all''.
  * Add service to zone: ''firewall-cmd --zone public --add-service httpd --permanent''.
  * Add source to zone: ''firewall-cmd --zone public --add-source 10.1.2.3 --permanent''.
  * Reload with new config: ''firewall-cmd --reload''.
=== - Configure key-based authentication for SSH===
  * Generate key pair: ''ssh-keygen -t <type>''.
  * Put public key in ''~/.ssh/authorized_keys'' on remote server.
=== - Set enforcing and permissive modes for SELinux===
  * Enforcing: ''setenforce 1''.
  * Permissive: ''setenforce 0''.
  * Edit ''/etc/selinux/config'' for permanent configuration.

=== - List and identify SELinux file and process context===
  * Files: ''ls -lZ''.
  * Processes: ''ps -efZ''.

=== - Restore default file contexts===
  * Restore file contexts: ''restorecon -Rv /var/www/html''.
  * 
=== - Use boolean settings to modify system SELinux settings===
  * Get booleans: ''getsebool -a''.
  * Set boolean: ''setsebool <boolean> <value>'', use ''-P'' for permanent (at boot time).

=== - Diagnose and address routine SELinux policy violations===
  * Check ''/var/log/audit/audit.log''.
  * Read selinux man pages.
  * Quick and dirty solution: ''audit2allow''.