The SUSE Certified Administrator in Enterprise Linux 15 (sca_sles15)

The command that will display the value of a variable named TMPDIR is echo TMPDIR.Theechocommandwillprintitsargumentstothestandardoutput.The sign is used to reference the value of a variable in bash. If you omit the $ sign, echo will print the name of the variable instead of its value. If you use single quotes around the variable name, echo will also print the name instead of its value. If you use double quotes around the variable name, echo will print its value as expected. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-bash.html#sec-bash-variables

Firewalld uses two separated configuration sets, runtime, and permanent configuration.

The runtime configuration is the actual running configuration and it is not persistent on reboots. When the firewalld service starts it loads the permanent configuration which becomes the runtime configuration.

https://www.supportsages.com/everything-you-need-to-know-about-firewalld/#:~:text=Firewalld%20uses%20two%20separated%20configuration,which%20becomes%20the%20runtime%20configuration .

Firewalld maintains two separate configurations: runtime and permanent. The runtime configuration is the current state of the firewall that is applied to the system. It can be changed by various commands and tools without affecting the permanent configuration. The permanent configuration is the persistent state of the firewall that is stored in configuration files. It can be changed by various commands and tools with the --permanent option. The permanent configuration will take effect after reloading firewalld or rebooting the system. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-firewall-firewalld.html#sec-firewall-firewalld-config

The recommended file system for data volumes is XFS. XFS is a high-performance and scalable file system that supports large files and file systems, online defragmentation and resizing, metadata checksums, and other features. XFS is the default file system for data partitions in SLES 15. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-filesystems.html#sec-filesystems-xfs

The file that contains the list of DNS servers SLES will contact is /etc/resolv.conf. This file specifies one or more nameserver addresses that will be used to resolve hostnames to IP addresses. It may also contain other options such as search domains, sort lists, etc. The /etc/resolv.conf file can be generated automatically by network configuration tools or edited manually by the administrator. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-network-dns.html#sec-network-dns-resolv.conf

The term “action” means an action that defines where a log message ends up such as in a regular file or database table when referring to system logging in SUSE Linux Enterprise. An action is part of a rule that specifies how to process a log message based on its properties. An action can be one of the following types: file, pipe, shell, template, discard, stop, call, omusrmsg, ommysql, ompgsql, etc. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-syslog.html#sec-syslog-config-actions

The commands that can be used to terminate processes are kill and killall. The kill command can be used to send a signal to a process specified by its process ID (PID). The default signal is SIGTERM, which requests a graceful termination of the process. The killall command can be used to send a signal to one or more processes specified by their name. It will match all processes that belong to the current user unless otherwise specified. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-cli-processes.html#sec-cli-processes-kill

The option for zypper that will list the available patches is zypper lp. This command will display a table of patches that are applicable to your system but not yet installed. It will show the patch name, category, severity, summary, and status for each patch. You can use zypper patch to install all available patches or zypper patch-info to get more details about a specific patch. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-zypper.html#sec-zypper-patches

The two commands that are commonly used to compile and install from source code are ./configure and make install. The ./configure command will check the system for dependencies, set variables, and generate a Makefile. The make install command will use the Makefile to compile the source code and copy the binaries and files to the appropriate locations. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-software-install-source.html

The -U option will install a package whether or not a previous version of the package is already installed. If a previous version exists, it will be upgraded. The -F option will install a package only if a previous version of the package is already installed. It will not install a new package. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-sw-cl.html#sec-rpm-commands