- Details
- Lubos Rendek
- Redhat / CentOS
In this tutorial you will learn:
- What are symbolic (soft) links
- What are hard links
- How to create a symbolic link
- How to create a hard link
- How to remove link
- Details
- Lubos Rendek
- Redhat / CentOS
RHCSA is a must have certification for anyone serious about getting a Linux system administration job. This RHCSA Exam Preparation Guide is currently under construction but is regularly updated with new topics. Please check back later.
If you are a beginner or somewhat new to GNU/Linux do not waste time by waiting but get started with a GNU/Linux command line basics before you do anything else. Understanding the GNU/Linux command line is an absolute must and will take you a long way on your RHCSA exam.
Understand and use essential tools
- Access a shell prompt and issue commands with correct syntax
- Use input-output redirection (>, >>, |, 2>, etc.)
- Use grep and regular expressions to analyze text
- Access remote systems using SSH
- Log in and switch users in multiuser targets
- Archive, compress, unpack, and uncompress files using tar, star, gzip, and bzip2
- Create and edit text files
- Create, delete, copy, and move files and directories
- Create hard and soft links
- List, set, and change standard ugo/rwx permissions
- Locate, read, and use system documentation including man, info, and files in /usr/share/doc
Operate running systems
- Boot, reboot, and shut down a system normally
- Boot systems into different targets manually
- Interrupt the boot process in order to gain access to a system
- Identify CPU/memory intensive processes and kill processes
- Adjust process scheduling
- Locate and interpret system log files and journals
- Preserve system journals
- Start, stop, and check the status of network services
- Securely transfer files between systems
Configure local storage
- List, create, delete partitions on MBR and GPT disks
- Create and remove physical volumes
- Assign physical volumes to volume groups
- Create and delete logical volumes
- Configure systems to mount file systems at boot by universally unique ID (UUID) or label
- Add new partitions and logical volumes, and swap to a system non-destructively
Create and configure file systems
- Create, mount, unmount, and use vfat, ext4, and xfs file systems
- Mount and unmount network file systems using NFS
- Extend existing logical volumes
- Create and configure set-GID directories for collaboration
- Configure disk compression
- Manage layered storage
- Diagnose and correct file permission problems
Deploy, configure, and maintain systems
- Schedule tasks using at and cron
- Start and stop services and configure services to start automatically at boot
- Configure systems to boot into a specific target automatically
- Configure time service clients
- Install and update software packages from Red Hat Network, a remote repository, or from the local file system
- Work with package module streams
- Modify the system bootloader
Manage basic networking
- Configure IPv4 and IPv6 addresses
- Configure hostname resolution
- Configure network services to start automatically at boot
- Restrict network access using firewall-cmd/firewall
Manage users and groups
- Create, delete, and modify local user accounts
- Change passwords and adjust password aging for local user accounts
- Create, delete, and modify local groups and group memberships
- Configure superuser access
Manage security
- Configure firewall settings using firewall-cmd/firewalld
- Configure key-based authentication for SSH
- Set enforcing and permissive modes for SELinux
- List and identify SELinux file and process context
- Restore default file contexts
- Use boolean settings to modify system SELinux settings
- Diagnose and address routine SELinux policy violations
- Details
- admin
- Redhat / CentOS
hostname of your CentOS 7 Linux is defined by the file /etc/hostname thus setting a new hostname for your system is just a matter of editing this file and replace a current hostname definition line with new one. However, doing so will not update your system;s hostname immediately thus a preferred way of changing a hostname on CentOS 7 Linux is to use nmtui and more specifically its child nmtui-hostname. Using nmtui-hostname tool will make the process of changing your hostname rather simple as executing a single command. The following linux command will change the hostname to linuxconfig.org:
# nmtui-hostname linuxconfig.org
- Details
- Lubos Rendek
- Redhat / CentOS
sudo command allows regular users to execute commands with administrative/root privileges. By adding any user to predefined sudo group wheel will grant root privileges to execute any command as root user. Any attempt to use the sudo command for the non-sudo user will result in:
user is not in the sudoers file. This incident will be reported.In this tutorial you will learn:
- How to create sudo user on RHEL 8 / CentOS 8 system.
- How to add existing user to sudoers.
- Details
- Lubos Rendek
- Redhat / CentOS
firewalld firewall. The FTP protocol is primarily used by file transfer services such as, but not limited to, vsftpd FTP server. For more information visit our introduction guide to firewalld syntax and usage guide.
In this tutorial you will learn:
- How to open FTP port 21.
- How to open FTP port 21 permanently.
- How to list currently open ports/services.
- How to close/remove open FTP port 21.
- Details
- Lubos Rendek
- Redhat / CentOS
systemctl command.
In this tutorial you will learn:
- How to enable service to start on boot.
- How to list all services on systemd Linux system.
- Details
- Lubos Rendek
- Redhat / CentOS
firewalld firewall. HTTP and HTTPS protocols are primarily used by web services such as, but not limited to, Apache or Nginx web serves.For more information about the
firewalld firewall visit our introduction guide to firewalld syntax and usage guide.
In this tutorial you will learn:
- How to open HTTP port 80 and HTTPS port 443.
- How to open HTTP port 80 and HTTPS port 443 permanently.
- How to list currently open ports/services.
- How to close/remove HTTP port 80 and HTTPS port 443.
- Details
- Thomas Sandmann
- Redhat / CentOS
In this tutorial we will learn how to install Apache Tomcat 8 application container to RHEL 8 / CentOS 8. We will be using the zip package available to download from the Apache Tomcat website. As this package will not handle setting up the environment, we will create it from the command line.
In this tutorial you will learn:- How to install Apache Tomcat from zip file
- How to create the environment for the Tomcat server from command line
- How to add basic service file to systemd
- How to enable autostart, start and stop the Tomcat server
- How to verify Tomcat is reachable
- Details
- Lubos Rendek
- Redhat / CentOS
In this tutorial you will learn:
- How to open and close ports on RHEL 8 / CentOS 8 with Firewalld.
- How to open and close services on RHEL 8 / CentOS 8.
- How to reload firewall configuration.
- How to list open ports or services.
- Details
- Lubos Rendek
- Redhat / CentOS
The nftables framework replaces iptables as a default network packet filtering feature on RHEL 8.
# firewall-cmd --list-all public (active) target: default icmp-block-inversion: no interfaces: enp0s3 sources: services: cockpit dhcpv6-client ssh ports: protocols: masquerade: no forward-ports: source-ports: icmp-blocks: rich rules:In this tutorial you will learn:
- How to check the firewall status onRHEL 8 / CentOS 8.
- How to stop firewall on RHEL 8 / CentOS 8.
- How to start firewall on RHEL 8 / CentOS 8.
- How to permanently disable firewall on RHEL 8 / CentOS 8.
- How to enable firewall to start after reboot.
- Details
- Lubos Rendek
- Redhat / CentOS
timedatectl.
In this tutorial you will learn:
- How to retrieve current timezone.
- How to change/set timezone.
- Details
- Lubos Rendek
- Redhat / CentOS
There are several ways on how to check what version of CentOS is running on your system. The simplest way to check for the CentOS version number is to execute the cat /etc/centos-release command. Identifying the accurate CentOS version may be required to help you or your support team to troubleshoot your CentOS system.
- Details
- Fabrizio Pani
- Redhat / CentOS
This guide will show how to install and configure a DNS Server in RHEL 8 / CentOS 8 in caching mode only or as single DNS Server, no master-slave configuration. A reverse and forward zone example is provided.
In this tutorial you will learn:- How to install a DNS server in RHEL 8 / CentOS 8
- How to configure a server as caching only DNS Server
- How to configure a server as single DNS Server
- Details
- Răzvan T. Coloja
- Redhat / CentOS
Minecraft is still a popular game these days. The simplicity of its graphics had an appeal on gamers of all ages and there are many hundreds of thousands of players worldwide, most of them playing on online servers. But did you know you can create your own Minecraft server using RedHat Enterprise Linux 8? Here is a how to teaching you exactly how to do it.
In this tutorial you will learn:- How to install Java
- How to download and run a Minecraft server
- How to create a user for the Minecraft server
- How to open the Minecraft port
- Details
- Răzvan T. Coloja
- Redhat / CentOS
Most IPs these days are automatically assigned through DHCP by either your ISP or your home router. But there may come a time when you wish to opt for a static IP address and you will want to change it. It may be that you are configuring a home LAN and you don't want to use DHCP or simply want a static IP address that you can access from outside your home. In this tutorial we will learn how we can change the IP address in RHEL 8 / CentOS 8 Linus system.
In this tutorial you will learn:- How to change the IP address in RHEL 8 / CentOS 8 using GNOME
- How to change the IP address by editing configuration files
- How to manually change your DNS server
- How to restart networking in RHEL 8 / CentOS 8
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