#chgrp command

[kandztuts]

Linux CLI 20 🐧 chgrp, chown and passwd commands

New Post has been published on https://tuts.kandz.me/linux-cli-20-%f0%9f%90%a7-chgrp-chown-and-passwd-commands/

Linux CLI 20 🐧 chgrp, chown and passwd commands

chgrp stands for change group It is used to change one group's or file's ownership adds a group. In some distros it can be addgroup It changes the group of 1.txt file You can change the group to multiple files It changes the group for d2 directory and the files within it It changes the group for 1.txt file using the group of a chown stands for change owner it is used to change the ownership of files and directories it changes the owner of 1.txt to root it changes the owner of a to root and gives a feedback It changes the owner of d3 directory and the files within it You can also change the owner and the group by using user:group it changes the owner and the group for log.txt List the users on the system It displays information about specific user password passwd -l username → it locks the password for a specific user passwd -u username → it unlocks the password for a specific user passwd -d username → it deletes the user password passwd -e username → it expires the user password passwd -n 5 username → set the days of password expiration

[anaa11111]

Title: 10 Essential Linux Commands Every User Should Know

Linux is a popular operating system known for its stability, security, and flexibility. It is widely used in servers, supercomputers, and embedded devices. Linux commands are an essential part of the operating system, allowing users to perform various tasks and manage files, directories, and system settings. In this blog post, we will discuss the 10 essential Linux commands every user should know.

ls: The ‘ls’ command is used to list the files and directories in the current directory. It can display the file names, sizes, and modification dates. The command can also be used with various options to display hidden files, sort files by size or modification date, and more.

cd: The ‘cd’ command is used to change the current directory. It can be used to navigate to a specific directory or to move up and down the directory hierarchy. The command can also be used with relative or absolute paths to navigate to a specific location.

cp: The ‘cp’ command is used to copy files and directories. It can be used to copy a single file, a group of files, or an entire directory. The command can also be used with various options to preserve file attributes, overwrite existing files, and more.

mv: The ‘mv’ command is used to move or rename files and directories. It can be used to move a file or directory to a new location or to rename a file or directory. The command can also be used with various options to preserve file attributes and overwrite existing files.

rm: The ‘rm’ command is used to remove files and directories. It can be used to delete a single file, a group of files, or an entire directory. The command can also be used with various options to force the deletion of non-empty directories, preserve file attributes, and more.

mkdir: The ‘mkdir’ command is used to create new directories. It can be used to create a single directory or a group of directories. The command can also be used with various options to create directories with specific permissions, create directories in a specific location, and more.

rmdir: The ‘rmdir’ command is used to remove empty directories. It can be used to remove a single directory or a group of directories. The command can also be used with various options to force the removal of non-empty directories, preserve file attributes, and more.

chmod: The ‘chmod’ command is used to change the permissions of files and directories. It can be used to change the read, write, and execute permissions for the owner, group, and others. The command can also be used with various options to change permissions recursively, change permissions based on a mode, and more.

chown: The ‘chown’ command is used to change the ownership of files and directories. It can be used to change the owner and group of a file or directory. The command can also be used with various options to change ownership recursively, change ownership based on a user or group ID, and more.

chgrp: The ‘chgrp’ command is used to change the group ownership of files and directories. It can be used to change the group ownership of a file or directory. The command can also be used with various options to change group ownership recursively, change group ownership based on a group name, and more.

Conclusion: These 10 essential Linux commands are the foundation of Linux command-line management. By mastering these commands, users can perform various tasks, manage files and directories, and manage system settings. These commands are versatile and can be used in various situations, making them essential for any Linux user.

[linuxtrainingtips]

Linux Course: Unlocking the Power of Open-Source Operating Systems

In the world of technology, Linux stands as one of the most important and versatile operating systems. Whether you are an aspiring system administrator, a software developer, or someone interested in IT infrastructure, learning Linux is an essential skill that can open doors to countless career opportunities. This article will guide you through the key aspects of a Linux course, its benefits, what you will learn, and why it matters in today’s digital landscape.

What is Linux?

Linux is an open-source operating system kernel first released by Linus Torvalds in 1991. Unlike proprietary operating systems such as Windows or macOS, Linux is freely available to anyone and can be modified or distributed under the GNU General Public License. Over time, Linux has grown into a robust and secure OS powering everything from personal computers and servers to smartphones, embedded systems, and even supercomputers.

Many different versions, called distributions (distros), exist today — including Ubuntu, CentOS, Debian, Fedora, and Red Hat Enterprise Linux (RHEL). Each distro serves different purposes but shares the core Linux kernel and principles.

Why Learn Linux?

Linux skills are highly sought after in the IT industry due to the system's widespread use in servers, cloud computing, cybersecurity, and development environments. Here are some key reasons to take a Linux course:

Career Opportunities: Many organizations run their servers on Linux. Roles such as Linux System Administrator, DevOps Engineer, Cloud Engineer, and Security Analyst require solid Linux knowledge.

Open Source Advantage: Linux promotes transparency and customization, empowering users to learn deeply about how an OS functions.

Server and Cloud Dominance: Around 70% of web servers globally run Linux-based OSes, and cloud platforms like AWS, Google Cloud, and Azure rely heavily on Linux.

Stability and Security: Linux is known for its reliability and security, making it the preferred OS for critical applications.

Free and Flexible: Unlike Windows licenses, Linux distros are free, making it ideal for learning and experimentation.

Who Should Take a Linux Course?

A Linux course is valuable for a range of learners, including:

IT professionals looking to enhance their skills

Beginners interested in technology and open-source software

Developers aiming to build or deploy applications on Linux servers

System administrators managing network and server infrastructures

Cybersecurity enthusiasts focusing on penetration testing and ethical hacking

What Will You Learn in a Linux Course?

A well-structured Linux course covers fundamental to advanced topics, ensuring a holistic understanding of the OS. The following are the typical modules included:

1. Introduction to Linux

History and evolution of Linux

Overview of Linux distributions

Understanding open source and licensing

Installing Linux on virtual machines or physical hardware

2. Linux File System and Commands

Directory structure and file system hierarchy (/, /home, /etc, /var, etc.)

Basic shell commands (ls, cd, pwd, mkdir, rm, cp, mv)

File permissions and ownership (chmod, chown, chgrp)

Understanding files (regular, directories, symbolic links, special files)

3. Working with the Shell

Introduction to the command-line interface (CLI)

Bash shell basics

Command chaining, piping, and redirection

Environment variables and shell scripting basics

4. User and Group Management

Creating and managing users and groups

Password policies and security

Switching users and managing permissions

5. Package Management

Installing and managing software packages (using apt, yum, dnf, or zypper)

Updating and removing software

Working with repositories

6. Process and Service Management

Understanding processes and jobs

Process monitoring commands (ps, top, htop)

Managing system services (systemctl, service)

Scheduling tasks with cron and at

7. Networking Basics

Configuring network interfaces

Understanding IP addressing, DNS, and routing

Testing network connectivity (ping, traceroute, netstat)

SSH basics for remote access

8. Disk Management

Partitioning disks using fdisk and parted

Mounting and unmounting file systems

Disk quotas and monitoring disk usage (df, du)

9. System Monitoring and Troubleshooting

Logs management and analysis (/var/log)

Monitoring CPU, memory, and storage usage

Basic troubleshooting commands and techniques

10. Security Essentials

Firewalls (iptables, firewalld)

SELinux basics

SSH key-based authentication

Configuring sudo for privilege escalation

11. Advanced Topics (Optional, Depending on Course)

Kernel modules and compilation

Containers and virtualization (Docker, KVM)

Automating with Ansible or other configuration management tools

Setting up web servers (Apache, Nginx)

Database basics on Linux (MySQL, PostgreSQL)

Benefits of Completing a Linux Course

Hands-on Experience

Most Linux courses emphasize practical exercises that let you work in a real Linux environment. This hands-on practice is vital because Linux proficiency comes from doing, not just theory.

Certification Opportunities

Many Linux courses prepare students for certifications such as the CompTIA Linux+, Red Hat Certified System Administrator (RHCSA), or Linux Professional Institute Certification (LPIC). These certifications enhance your resume and demonstrate validated skills to employers.

Improved Problem-Solving Skills

Linux encourages users to understand system internals and troubleshoot issues using command-line tools. This builds a logical and analytical mindset that benefits all areas of IT.

Cost-Effective Learning

Linux is free to download and install, so you don’t need to invest in costly software licenses to practice and learn.

Versatility Across Platforms

Once proficient in Linux, you can work on cloud platforms, embedded devices, and even Windows Subsystem for Linux (WSL) on Windows machines, greatly expanding your environment options.

How to Choose the Right Linux Course?

With many Linux courses available online and offline, choosing the right one depends on your goals and learning style. Consider the following:

Course Level: Beginners should start with foundational courses; advanced users might seek specialized training.

Instructor Credentials: Look for courses taught by experienced professionals or recognized institutions.

Practical Labs: Ensure the course offers hands-on labs or virtual environments.

Certification Preparation: If certification is your goal, pick courses aligned with certification exams.

Community and Support: Courses with active forums or support channels help resolve doubts quickly.

Cost and Duration: Compare prices and course lengths to fit your budget and schedule.

Recommended Linux Learning Resources

Online Platforms: Coursera, Udemy, edX, Linux Foundation Training

Books: "Linux Command Line and Shell Scripting Bible" by Richard Blum, "How Linux Works" by Brian Ward

Linux Distributions: Start with beginner-friendly distros like Ubuntu or Fedora for practice

Practice Labs: Websites like Linux Academy, Katacoda, and OverTheWire offer interactive labs

Final Thoughts

Learning Linux is not just about mastering an operating system; it’s about embracing an open-source philosophy that drives innovation worldwide. Whether you want to manage servers, automate tasks, or build software, a solid understanding of Linux can serve as a foundation for a rewarding tech career.

Taking a Linux course equips you with essential skills that are in high demand across industries, from tech startups to multinational corporations. The knowledge you gain can empower you to troubleshoot complex problems, automate repetitive tasks, and efficiently manage computing environments.

So, if you are passionate about technology and eager to build your IT skills, enrolling in a Linux course is a step in the right direction — one that opens up a world of possibilities.

[mr-wisecoder]

Установка и настройка QEMU/KVM в Ubuntu

В этой статье я хочу рассмотреть установку и настройку QEMU/KVM в Ubuntu.

Оглавление

ВведениеПроверка аппаратной поддержкиПодготовка сервераУстановка и запускНастройка сетиНастройка сетевого мостаВиртуальные сети (NAT forwarding)Создание виртуальной машиныУправление виртуальной машиной Введение в QEMU/KVM KVM (Kernel-based Virtual Machine) — это комплекс программ для виртуализации с аппаратной поддержкой в среде Linux x86. Виртуализация позволяет нам устанавливать полностью изолированные, но работающие бок о бок операционные системы на одном и том же железе. Гипервизор KVM представляет из себя загружаемый модуль ядра Linux. Он обеспечивает только уровень абстракции устройств. Таким образом одного гипервизора KVM недостаточно для запуска виртуальной ОС. Нужна еще эмуляция процессора, дисков, сети, видео, шины. Для этого существует QEMU. QEMU (Quick Emulator) — эмулятор различных устройств, который позволяет запускать операционные системы, предназначенные для одной архитектуры, на другой. ��бычно такой комплекс программ для виртуализации называют QEMU/KVM. Проверка аппаратной поддержки виртуализации Во-первых, перед настройкой KVM необходимо проверить совместимость сервера с технологиями виртуализации: cat /proc/cpuinfo | egrep -c "(vmx|svx)" Числа отличные от нуля говорят о том, что процессор имеет поддержку аппаратной виртуализации Intel-VT или AMD-V . Подготовка сервера Во-вторых, для удобства создадим каталоги для хранения образов жестких дисков наших виртуальных машин и образов ISO, с которых будет производиться установка операционных систем. sudo mkdir -p /kvm/{hdd,iso} В результате будет создан каталог /kvm/hdd для виртуальных жестких дисков и каталог /kvm/iso для образов ISO. Установка и запуск QEMU/KVM в Ubuntu В качестве интерфейса к технологиии виртуализации QEMU/KVM в Ubuntu мы будем использовать библиотеку libvirt. С помощью следующей команды мы установим гипервизор, эмулятор, библиотеку и утилиты управления. sudo apt-get install qemu-kvm libvirt-bin virtinst libosinfo-bin Где qemu-kvm — сам гипервизор; libvirt-bin — библиотека управления гипервизором; virtinst — утилита управления виртуальными машинами; libosinfo-bin — утилита для просмотра списка вариантов гостевых операционных систем. После успешной установки всех пакетов настроим автоматический запуск сервиса. sudo systemctl enable libvirtd Запустим его. sudo systemctl start libvirtd Пользователя, под которым будем работать с виртуальными машинами, включим в группу libvirt: sudo usermod -aG libvirt user И установим права доступа на ранее созданные каталоги: sudo chgrp libvirt /kvm/{hdd,iso} sudo chmod g+w /kvm/hdd Настраивать виртуальные машины, хранилища и сети можно как из командной строки, так и с помощью GUI-инструмента virt-manager. Причем установить его можно как на сервер, так и на другой компьютер, например, на ваш ноутбук. В последнем случае вам придется добавить удаленное соединение к libvirt. Установку virt-manager и работу при помощи него с libvirt и виртуальными машинами мы рассмотрим в следующей статье. Настройка сети Итак, виртуальные машины могут работать через свою виртуальную сеть с NAT или получать IP-адреса из локальной сети через сетевой мост, который нам необходимо настроить. Настройка сетевого моста В старых версиях Ubuntu большая часть настроек конфигурации сети Ethernet находится в файле /etc/network/interfaces. На всякий случай создадим его резервную копию: mkdir -p ~/backup && sudo cp /etc/network/interfaces ~/backup Затем устанавливаем утилиты для конфигурирования Ethernet-моста: sudo apt-get install bridge-utils Открываем файл /etc/network/interfaces в своем любимом редакторе (vim, nano): sudo vim /etc/network/interfaces И приводим его к примерно такому виду: source /etc/network/interfaces.d/* auto lo iface lo inet loopback #allow-hotplug eno1 #iface eno1 inet static # address 192.168.7.2/24 # gateway 192.168.7.1 # dns-nameservers 127.0.0.1 192.168.7.1 8.8.8.8 # dns-search home.lan auto br0 iface br0 inet static address 192.168.7.2/24 gateway 192.168.7.1 bridge_ports eno1 bridge_stp on bridge_fd 2 bridge_hello 2 bridge_maxage 20 dns-nameservers 127.0.0.1 192.168.7.1 8.8.8.8 dns-search home.lan Все, что закомментировано — старые настройки сети; br0 — название интерфейса создаваемого моста; eno1 — сетевой интерфейс, через который будет работать мост. Если вы получаете адрес динамически через DHCP, то конфигурация сократится до такой: source /etc/network/interfaces.d/* auto lo iface lo inet loopback auto br0 iface br0 inet dhcp bridge_ports eno1 bridge_stp on bridge_fd 2 bridge_hello 2 bridge_maxage 20 Внимательно проверяем конфигурацию и перезапускаем службу сети: sudo systemctl restart networking Начиная с релиза Ubuntu 17.10, для управления конфигурацией сети по умолчанию используется утилита Netplan, которая добавляет новый уровень абстракции при настройке сетевых интерфейсов. Конфигурация сети хранится в файлах формата YAML. Предоставляется эта информация бэкендам (network renderers), таким как NetworkManager или systemd-networkd. Файлы конфигурации Netplan хранятся в папке /etc/netplan. Для настройки сети открываем в редакторе файл 01-netcfg.yaml vim /etc/netplan/01-netcfg.yaml и приводим его к такому виду: network: version: 2 renderer: networkd ethernets: ens3: dhcp4: false dhcp6: false bridges: br0: dhcp4: false dhcp6: false interfaces: addresses: gateway4: 192.168.7.1 nameservers: search: addresses: parameters: stp: true forward-delay: 2 hello-time: 2 max-age: 20 Ну а при использовании динамической адресации файл конфигурации будет выглядеть так: network: version: 2 renderer: networkd ethernets: ens3: dhcp4: false dhcp6: false bridges: br0: dhcp4: true dhcp6: true interfaces: parameters: stp: true forward-delay: 2 hello-time: 2 max-age: 20 В файлах конфигурации указываем свои адреса, имена интерфейсов и доменов и после тщательной проверки применяем сетевые настройки: sudo netplan apply Виртульные сети (NAT forwarding) Каждая стандартная установка libvirt обеспечивает подключение виртуальных машин на основе NAT из коробки. Это так называемая виртуальная сеть по умолчанию. Вы можете проверить, что она доступна таким образом: sudo virsh net-list --all Name State Autostart Persistent ---------------------------------------------------------- default active yes yes Для того, чтобы виртуальные машины с сетевым интерфейсом NAT могли выходить в интернет необходимо настроить перенаправление сетевого трафика. Для этого надо убрать комментарий строки #net.ipv4.ip_forward=1 в файле /etc/sysctl.d/99-sysctl.conf и сохранить настройки: sudo vim /etc/sysctl.d/99-sysctl.conf sudo sysctl -p /etc/sysctl.d/99-sysctl.conf Создание виртуальной машины Для создания виртуальной машины нам понадобятся две утилиты: osinfo-query — для получения списка доступных для установки вариантов операционных систем и virt-install — непосредственно для самой установки. Итак, создадим нашу первую виртуальную виртуальную машину с ОС Ubuntu 16.04, 1024MiB ОЗУ, 1 процессором, сетью через мост и 12GiB жестким диском. sudo virt-install \ --name ubuntu1604s \ --os-type=linux --os-variant=ubuntu16.04 \ --vcpus=1 \ --ram 1024 \ --network network=bridge:br0 \ --disk path=/kvm/hdd/ubuntu1604s.qcow2,format=qcow2,size=12,bus=virtio \ --cdrom=/kvm/iso/ubuntu-16.04.6-server-amd64.iso \ --graphics vnc,listen=0.0.0.0 --noautoconsole \ --hvm --virt-type=kvm Обратите внимание на параметр --os-variant. Он указывает гипервизору под какую именно ОС следует адаптировать настройки. Список доступных вариантов можно получить, выполнив команду: osinfo-query os Подробнее с параметрами virt-install вы можете ознакомиться на страницах руководства, а я приведу команду создания ВМ c сетью через NAT: sudo virt-install \ --name ubuntu1604s \ --os-type=linux --os-variant=ubuntu16.04 \ --autostart \ --vcpus=2 --cpu host --check-cpu \ --ram 2048 \ --network network=default,model=virtio \ --disk path=/kvm/vhdd/ubuntu1604s.qcow2,format=qcow2,size=12,bus=virtio \ --cdrom=/kvm/iso/ubuntu-16.04.6-server-amd64.iso \ --graphics vnc,listen=0.0.0.0,password=vncpwd --noautoconsole \ --hvm --virt-type=kvm После запуска установки в консоли сервера вы увидите текст похожий на этот: Domain installation still in progress. Waiting for installation to complete. Значит все нормально и для продолжения установки ОС в виртуальной машине нам нужно соединиться к ней по VNC. Чтобы узнать номер порта на котором он поднят для нашей ВМ откройте новую консоль или в текущей переведите задание в фоновый режим с помощью CTRL+Z, bg и выполните команду: sudo virsh dumpxml ubuntu1604s | grep graphics В моем случае это порт 5903: или выполнив команду sudo virsh vncdisplay ubuntu1604s вы получите примерно такой результат: :3 Это число нужно сложить с базовым портом 5900. Далее подключаемся с помощью клиента VNC (Remmina, TightVNC) к нашему серверу по полученному порту и устанавливаем Ubuntu 16.04 в нашей ВМ.

После успешного завершения установки в консоли вы увидите примерно следующее: Domain has shutdown. Continuing. Domain creation completed. Restarting guest. Управление виртуальной машиной Для управления гостевыми системами и гипервизором существует текстовая утилита virsh. Она использует libvirt API и служит альтернативой графическому менеджеру виртуальных машин virt-manager. Я коснусь только основных команд управления ВМ, так как описание всех возможностей утилиты — тема для отдельной статьи. Список всех доступных команд вы можете увидеть так: virsh help Описание параметров отдельной команды: virsh help command где command — это команда из списка, который мы получили выше. Для просмотра списка всех виртуальных машин используйте: sudo vish list --all Вот что она показала у меня: Id Name State ---------------------------------------------------- 1 ubuntu16 running 3 centos8 running 6 ubuntu18 running 10 ubuntu1604server running - win10 shut off - win2k16 shut off - win2k16-2 shut off - win7 shut off Если же вам нужны только работающие в данный момент виртуалки, то введите: sudo virsh list Для запуска виртуальной машины выполните в консоли: sudo virsh start domain где domain — имя виртуальной машины из списка, который мы получили выше. Для выключения: sudo virsh shutdown domain И для ее перезагрузки: sudo virsh reboot domain Редактирование конфигурации ВМ: sudo virsh edit domain Read the full article

[computingpostcom]

How can I install Wireshark on Debian 11/10/9?. Wireshark is an open-source network analysis and packet capture tool commonly used in the world of Network Engineers. Wireshark is a cross-platform application and it runs on Linux, Windows, and macOS. You can operate it from a GUI or CLI – Your comfort area is the limit!. On Ubuntu, check: How to install Wireshark on Ubuntu Desktop Features of Wireshark Wireshark comes with a rich set of features like: Deep inspection of hundreds of protocols, with more being added all the time Live capture and offline analysis Standard three-pane packet browser Multi-platform: Runs on Windows, Linux, macOS, Solaris, FreeBSD, NetBSD, and many others Captured network data can be browsed via a GUI, or via the TTY-mode TShark utility The most powerful display filters in the industry Rich VoIP analysis Read/write many different capture file formats: tcpdump (libpcap), Pcap NG, Catapult DCT2000, Cisco Secure IDS iplog, Microsoft Network Monitor, Network General Sniffer® (compressed and uncompressed), Sniffer® Pro, and NetXray®, Network Instruments Observer, NetScreen snoop, Novell LANalyzer, RADCOM WAN/LAN Analyzer, Shomiti/Finisar Surveyor, Tektronix K12xx, Visual Networks Visual UpTime, WildPackets EtherPeek/TokenPeek/AiroPeek, and many others Capture files compressed with gzip can be decompressed on the fly Live data can be read from Ethernet, IEEE 802.11, PPP/HDLC, ATM, Bluetooth, USB, Token Ring, Frame Relay, FDDI, and others (depending on your platform) Decryption support for many protocols, including IPsec, ISAKMP, Kerberos, SNMPv3, SSL/TLS, WEP, and WPA/WPA2 Coloring rules can be applied to the packet list for quick, intuitive analysis Output can be exported to XML, PostScript®, CSV, or plain textInsta Install Wireshark on Debian 11/10/9 The quickest installation is from Debian repositories. sudo apt update sudo apt install wireshark When asked whether to allow non-superusers to capture packets, select your option and finish the installation. Confirm the version of Wireshark installed on Debian 10 / Debian 9 Desktop. $ apt policy wireshark wireshark: Installed: 3.4.10-0+deb11u1 Candidate: 3.4.10-0+deb11u1 Version table: *** 3.4.10-0+deb11u1 500 500 http://deb.debian.org/debian bullseye/main amd64 Packages 500 http://security.debian.org/debian-security bullseye-security/main amd64 Packages 100 /var/lib/dpkg/status Configure and start Wireshark To be able to capture packets as a normal user, add your user to wireshark group. sudo usermod -a -G wireshark $USER Also change dumpcap binary file permissions. sudo chgrp wireshark /usr/bin/dumpcap sudo chmod 750 /usr/bin/dumpcap sudo setcap cap_net_raw,cap_net_admin=eip /usr/bin/dumpcap Verify: $ sudo getcap /usr/bin/dumpcap /usr/bin/dumpcap = cap_net_admin,cap_net_raw+eip Starting Wireshark on Debian 10 / Debian 9 You can launch Wireshark on Debian 10 / Debian 9 from the terminal or Applications launcher. The same can be done from the command line by typing: $ wireshark Enjoy using Wireshark on Debian 10 (Buster) / Debian 9.

[fortunelomo]

Layouteditor user group

Layouteditor user group upgrade#

Layouteditor user group verification#

Layouteditor user group password#

Linux Execute Scheduled Tasks In A Loop (crontab Command).

Linux Execute Tasks Regularly (at Command).

Linux Run Background Commands Away From The Terminal (nohup Command).

Linux Resume Suspended Work in Background (bg Command).

Linux Restore Background Commands To Foreground (fg Command).

Linux Display The Jobs That Current Terminal Puts Into The Background (jobs Command).

Linux Kick User By Terminal Number (pkill Command).

Linux Kill A Specific Group Of Processes (killall Command).

Linux Change Process Priority (nice And renice Command).

Linux List Information About Files Called Or Opened By A Process (lsof Command).

Linux Display Process Tree (pstree Command).

Linux Continuously Monitor Process Running Status (top Command).

Linux Display Running Processes (ps Command).

Linux Query Disk Quota (quota And repquota Command).

Linux Set Disk Quota Non-interactively (setquota Command).

Linux Modify User (Group) Disk Quota (edquota Command).

Linux Turn Off Disk Quota Limits (quotaoff Command).

Linux Turn On Disk Quota Limit (quotaon Command).

Linux Scan FileSystem And Create A Quota File (quotacheck Command).

Linux Virtual Memory And Physical Memory.

Linux Format Hard Disk (mke2fs Command).

Linux Partition Large Capacity Hard Disk (parted Command).

Linux Partition Hard Disk (fdisk Command).

Linux Display FileSystem Information (dumpe2fs Command).

Linux Detect And Repair Filesystems (fsck Command).

Linux Unmount Filesystem (umount Command).

Linux Mount Files Outside The Linux System (mount Command).

Linux Count The Disk Space Occupied By A Directory Or File (du Command).

Linux Display File System Hard Disk Usage (df Command).

Linux System Permission Management (sudo Command).

Linux Display File And Directory Permission Attributes (lsattr Command).

Linux Modify File And Directory Permission Attributes (chattr Command).

Linux Stick BIT (SBIT) Special Permission.

Linux Create/Modify File And Directory Default Permissions (umask Command).

Linux Modify The File Or Directory Permissions (chmod Command).

Linux Modify The Owner And Group Of File And Directory (chown Command).

Linux Modify The Group Of File And Directory (chgrp Command).

The Importance Of Linux Permission Management.

Linux Switch The Effective Group Of Users (newgrp Command).

Linux Add User To Or Remove User From Group (gpasswd Command).

Linux Delete User Group (groupdel Command).

Linux Modify User Group (groupmod Command).

Linux Add User Group (groupadd Command).

Linux Switch Between Users (su Command).

Linux View User's UID And GID (id Command).

Layouteditor user group password#

Linux Modify User Password Status (chage Command).

Linux Modify User Information (usermod Command).

Linux Change User Password (passwd Command).

Linux Adding A New System User (useradd Command).

Linux Source Package Installation And Uninstallation.

Linux Extract RPM Package File (cpio Command).

Layouteditor user group verification#

Linux RPM Package Verification And Digital Certificates.

Layouteditor user group upgrade#

Linux RPM Package Installation, Uninstallation And Upgrade (rpm Command).Linux Find File Contents (grep Command).Linux Display The Ending Content Of File (tail Command).Linux Display File Content (less Command).Linux Display The Beginning Content Of File (head Command).Linux Display File Content by Paging (more Command).Linux Vim Batch Comments And Custom Comment.Linux Unzip ".bz2" File (bunzip2 Command).Linux Compress A File Or Directory to ".bz2" (bzip2 Command).Linux Unzip ".gz" File (gunzip Command).Linux Compress A File Or Directory to ".gz" (gzip Command).Linux Unzip ".zip" File (unzip Command).Linux Compress A File Or Directory to ".zip" (zip Command).Linux Move File Or Directory (mv Command).Linux Delete A File Or Directory (rm Command).Linux Copy File And Directory (cp Command).Linux Create Hard/Soft Links To File (ln Command).Linux Create File And Modify File Timestamp (touch Command).Linux Remove Empty Directory (rmdir Command).Linux Create A Directory (mkdir Command).linux View Files In A Directory (ls Command).

[ageethu35]

Linux Course Objectives

Detail orientation on the basic concepts Linux OS and the process of installation

Organised learning from basic to advanced level in Group administration, Mounting and Swap file systems, Backup and Recovery and various commands from

Learn inter active installation and network based installations

Get to know the Software Package management, and Booting and its installation

Application level idea on advanced file permissions : chmod, chown, chgrp& sticky bit

Shell scripting and Kerberos

[siva3155]

300+ TOP RED HAT LINUX SYSTEM ADMINISTRATION Objective Questions and Answers

RED HAT LINUX SYSTEM ADMINISTRATION Multiple Choice Questions :-

1. John works as a Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. He is working as a root user on the Linux operating system. He wants to add a soft limit quota warning for the users, in which, after exceeding the quota value, a user will receive e-mail warnings about being over quotA. Which of the following commands will John use to accomplish his task? Each correct answer represents a complete solution. Choose all that apply. A. repquota B. quotaon C. warnquota D. edquota E. quotaoff Answer: C, D 2. Which of the following commands will you run to list all files that have been modified within the last 60 minutes? A. find /etc -name *.txt B. find start -dir -min -60 C. find start -dir -cmin -60 D. find start -cmin -60 Answer: C 3. You work as a System Administrator for McNeil Inc. The company has a Linux based network. You are a root user on Red Hat operating system. You have upgraded the amount of RAM in your system from 256 MB to 512 MB, but there is only 512 MB of swap space. Therefore, you want to add more swap space to /dev/hdb2 hard drive to run the applications that require a large amount of memory. Which of the following commands should you run to accomplish this task? Each correct answer represents a complete solution. Choose all that apply. A. mkswap /dev/hdb2 B. swapon /dev/hdb2 C. mount D. parted Answer: A, B, D 4. You work as a Linux Technician for Tech Perfect Inc. The company has a Linux-based network. You have configured a database server in the network. Users complain that the server has become remarkably slow. However, the previous day, the server was performing well. You know that some of the processes may be the cause of the issue. You run the PS command on the server. In the result set, which information will you look at that suggests the problematic process? A. A high load average B. A high process ID C. A low load average D. A low CPU time E. A high CPU time Answer: E 5. You want only the root access in a Linux computer for maintenance purposes. Which of the following runlevels will you use to boot the computer? A. 2 B. 0 C. 1 D. 3 Answer: C 6. Which of the following commands can be used to compress a file? Each correct answer represents a complete solution. Choose all that apply. A. gzip B. compress C. tar D. zip Answer: A, B, D 7. You work as a Network Administrator for Rick Inc. The company has a Linux-based network. You are configuring a Linux server. Which of the following bootloaders does not require to be rewritten after the configuration of the kernel has been changed? A. GRUB B. BOOTP C. LILO D. ELILO Answer: A 8. Which of the following fsck commands will you use to check all filesystems listed in /etc/fstab? A. fsck -P B. fsck -f C. fsck -A D. fsck -y Answer: C 9. After enabling shadowed passwords in a Linux server, where does Linux keep the passwords? A. /usr/shadow B. /etc/passwd C. /usr/passwd D. /etc/shadow Answer: D 10. You work as a Software Engineer for McNiel Inc. The company has a Linux-based network. The company has 150 Engineers. The root user has configured quota limits for each user. You want to view quota limits for your system. Which of the following commands will you use to accomplish this task? A. repquota -a B. quota -v C. quotacheck D. edquota Answer: B

RED HAT LINUX SYSTEM ADMINISTRATION MCQs 11. Which of the following commands is used to create a user account for a new user? A. USERMOD B. MOUNT C. USERADD D. CRUSER Answer: C 12. You work as a Network Administrator for Tech Perfect Inc. The company has a Linux-based network. You are configuring a server that will be used as a file server. You want to install an RPM package, named FILELOCATOR, on the server. You want to check whether the package is already installed. Which of the following commands will you use? A. grep FILELOCATOR B. find -q rpm | grep FILELOCATOR C. rpm -qa | grep FILELOCATOR D. find FILELOCATOR Answer: C 13. By default, which of the following commands configures the current run level? A. chkconfig B. pstree C. service D. ntsysv Answer: D 14. When installing RHEL in the graphical interface, which of the following switches can be used to specify a resolution? A. lowers B. vnc C. resolution D. skipddc Answer: C 15. You work as a Network Administrator for Net World International. The company has a Linux-based network. You want to upgrade an RPM package and get the status during the upgrade. Which of the following commands will you use to accomplish the task? A. rpm -ivh B. rpm -evh C. rpm -qvh D. rpm -Uvh Answer: D 16. John works as a Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. John is working as a root user on the Linux operating system. He wants to run the cc process at runlevel three. If the order of execution of cc command is 43, which of the following commands will John use to accomplish his task? A. ln -s /etc/init.d/cc /etc/rc.d/rc3.d/K43cc B. ln -s /etc/rc.d/init.d/cc /etc/rc.d/rc3.d/K43cc C. ln -s /etc/rc.d/cc /etc/rc.d/rc3.d/s43cc D. ln -s /etc/rc.d/init.d/cc /etc/rc.d/rc3.d/S43cc Answer: D 17. Which of the following commands displays a module name or filename and associated information, such as the authors name, license, description, module version, dependencies, parameters, etc? A. modprobe B. lsmod C. modprob D. modinfo Answer: D 18. After creating the swap area, which of the following commands will you need to run to start using it? A. mkswap B. mkfs C. swapon D. swapoff Answer: C 19. You work as a Network Administrator for Secure Web Inc. The company has a Linux-based network. The network has a mixed set of client operating systems. You want to format a new hard disk drive. The drive will have only one partition. Both the Linux and Windows operating systems will access the partition. Which of the following file systems will you use? A. VFAT B. XFS C. REISER D. EXT3 Answer: A 20. What is the minimum RAM requirement for installing Red Hat in GUI mode? A. 1GB B. 512 MB C. 128MB D. 64MB Answer: C 21. Fill in the blank with the appropriate command. The ________ command recursively removes files, which have not been accessed for a period of time. A. tmpwatch Answer: A 22. Which of the following commands can be used to modify kernel parameters at runtime? A. sync B. sysctl C. mkinitrd D. lsdev Answer: B 23. You want to verify the PGP signature of all headers and signatures associated with an RPM package. Which of the following commands will you use to accomplish the task? Each correct answer represents a complete solution. Choose all that apply. A. rpm -e B. rpm -K C. rpm --checksig D. rpm -V Answer: B, C, D 24. Which of following options will you use to force mtr to display numeric IP numbers and not try to resolve the host names? A. -t B. -n C. -l D. -p Answer: B 25. Which of the following statements are true about kernel modules? Each correct answer represents a complete solution. Choose all that apply. A. Kernel modules do not support executable loaders. B. The kernel module contains extra kernel codes that may be loaded after the loading of the base kernel. Only a minimal resident kernel is loaded into memory at boot time. C. Kernel modules do not support the device drivers, network drivers, and file system drivers. D. Whenever a user requests a feature that is not present in the resident kernel, a kernel module is dynamically loaded into memory. Answer: B, D 26. You want to temporarily change your primary group to another group of which you are a member. In this process, a new shell will be created, and when you exit the shell, your previous group will be reinstated. Which of the following commands will you use to accomplish this task? A. chgrp B. newgrp C. chmod D. chown Answer: B 27. You want to make Rick an owner of the files TRADE1.TXT and TRDREPORT.TXT. Which of the following commands will you use to accomplish this? A. chown rick TRADE1.TXT TRDREPORT.TXT B. chgrp rick TRADE1.TXT + TRDREPORT.TXT C. chown rick TRADE1.TXT + TRDREPORT.TXT D. chgrp rick TRADE1.TXT TRDREPORT.TXT Answer: A 29. You work as a Network Administrator for McNeil Inc. The company has a Linux-based network. You are a root user on the Linux system. You have to create a user named Trinity and deny interactive login. Which of the following should you use to accomplish the task? Each correct answer represents a part of the solution. Choose all that apply. A. vi /etc/passwd B. vi /etc/shadow C. useradd Trinity D. passwd Trinity E. Trinity:x:505:505::/home/Trinity:/sbin/nonlogin Answer: A, B, C, D, E 30. Which of the following commands can be used to check the errors of the ext2 and ext3 filesystems? Each correct answer represents a complete solution. Choose two. A. fsck --ext2 B. fsck.ext3 C. fsck --ext3 D. e2fsck Answer: B, D RED HAT LINUX SYSTEM ADMINISTRATION Objective type Questions with Answers 31. Which of the following statements is true about fdisk command? A. It is used to build a Linux file system on a device, usually a hard disk partition. B. It is used to create, change, delete, or display current partitions on the hard disk. C. It is used to check and optionally repair one or more Linux file systems. D. It displays or changes the filesystem label on the ext2 filesystem located on device. Answer: B 32. You have recently been appointed as a Network Administrator for Rick International Inc. The company has a Linux-based network. You have to print an important file named secure.txt urgently. You therefore want to know what printers are currently configured on your computer and how you can connect to them. Which of the following commands will you use to accomplish the task? A. lpstat -s B. lpstat -d C. lpr D. lpstat -p Answer: A 33. You want to uninstall an rpm package foo without verifying its dependencies. Which of the following commands will you use? A. rpm --erase --allmatches B. rpm -e --allmatches C. rpm -e --noscript D. rpm -e --nodeps Answer: D 34. During the boot process of a Linux computer, which of the following daemons is called after the kernel is loaded? A. LPD B. TELNETD C. INIT D. RLOGIND Answer: C 35. You work as a Network Administrator for McNeil Inc. The company has a Linux-based network. You have just created a directory named Sales on a file server. David, a Sales Manager, has to use this directory to keep sales reports. David reports that he is unable to save his reports in the directory. When you list the directory using the LS command, you get the following result: drwxr-xr-x 2 root root 2048 Jan 2 2006 Sales What is the most likely cause? A. The Sales directory is not properly mounted. B. David is working on his local computer's login. C. The Sales directory has been deleted by accident. D. David does not have the Write permission on the directory. Answer: D 36. You want to shrink a Logical Volume manager partition named /dev/disk1/lvm from 4GB to 3GB. Which of the following commands can you use to accomplish the task? Each correct answer represents a complete solution. Choose all that apply. A. lvreduce B. resize2fs C. lvsize D. reduce2fs Answer: A,B 37. John works as a Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. Due to some network security reasons, John wants to shut down all network interfaces just before rebooting the Linux server. Which of the following commands will he use to accomplish the task? A. init 3 B. init 6 C. init 0 D. shutdown -r now E. reboot -i Answer: E 38. You work as a Network Administrator for Tech World Inc. The company has a Linux-based network. The permissions on a file named Report are shown below: rwxr--r— You want to add a sticky bit to the file. Which of the following commands will you use? A. chmod 2744 report B. chmod 1744 report C. chmod 7744 report D. chmod 4744 report Answer: B 39. Which of the following statements is true about Linux kernel? Each correct answer represents a complete solution. Choose all that apply. A. It constitutes the core part of the Linux operating system. B. It detects hardware resources and boots up the system. C. It allocates memory on behalf of running process. D. It does not verify firewall rules Answer: A, B, C 40. Which of the following commands is used to make a swap active after creating a new SWAP partition? A. mkswap B. swapon C. fdisk D. mkfs Answer: A 41. In a Linux computer, which of the following files defines run levels for the processes to be started up during boot up? A. /etc/inittab B. /etc/syslog.conf C. /etc/lilo.conf D. /etc/runlevel Answer: A 42. You work as a Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. You have to create user accounts for four new Management Trainees. You also have to create a group named MT and provide membership of this group to the new user accounts. How will you accomplish this? A. Use the ADDUSER command to create new user accounts and the MT group. Add the users account to the group. B. Use the USERADD command to create new user accounts and the MT group. Add the user accounts to the group. C. Use the GROUPADD command to create the MT group. Use the USERADD command to create the user accounts and provide them the membership of the MT group. D. Use the ADDGROUP command to create the MT group. Use the ADDUSER command to create the user accounts and provide them the membership of the MT group. Answer: C 43. John works as a Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. John is working as a root user on the Linux operating system. He wants to check the errors of an ext2 filesystem. Which of the following commands can John use to accomplish the task? Each correct answer represents a complete solution. Choose all that apply. A. e2fsck B. fsck C. fsck -N D. fsck.ext2 Answer: A, B, D 44. You work as a Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. You have received an error on your Linux server stating that the superblock is damaged. Which of the following commands will you use to resolve the issue? A. mount B. e2fsck C. fsck D. mkfs Answer: B 45. You work as a Network Administrator for Mac World Inc. The company has a Linux-based network. Your Linux computer turns off because of power outage. The UPS was unable to provide backup power. Which of the following utilities will run automatically during the next boot to scan the hard disk for the possibility of file system damage? A. mkfs B. mount C. scanfs D. fsck Answer: D 46. Which of the following files is used to view the current status of RAID devices in Linux? A. /proc/mdstat B. /proc/stat C. /proc/meminfo D. /proc/mounts Answer: A 47. Which of the following network protocols are used by the dhclient command to configure the IP addresses of computers on the network? A. The dhclient command does not use any protocol. It statically assigns the address to the network computers. B. RARP and DHCP C. BOOTP and DHCP D. BOOTP and RARP Answer: C 48. You work as a system administrator for Tech Perfect Inc. The company has a Linux-based network. You are a root user on the Linux operating system. A user, Jetson, wants to view the speed and the duplex for his Ethernet card. His ethernet card is activated on interface eth0. Which of the following commands can you use to accomplish this task? A. ifup eth0 B. ifconfig eth0 C. ip link show eth0 D. sudo ethtool eth0 Answer: D 49. Which of the following files are used to activate disk quotas on a file system? Each correct answer represents a complete solution. Choose all that apply. A. quotA.group B. quotA.user C. quotaon D. .quotaon Answer: A, B 50. You work as a Network Administrator for Perfect Solutions Inc. You are required to configure a hard disk for a Linux workstation. You are using the FDISK utility to configure it. Which of the following options will you use to show all the existing partitions of the hard disk? A. n B. w C. 1 D. p Answer: D 51. John works as a Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. John is working as a root user on the Linux operating system. He wants to print a file named print.txt. Which of the following commands can John use to accomplish the task? Each correct answer represents a complete solution. Choose all that apply. A. lpr B. lprm C. lp D. a2ps Answer: A, C 52. Which of the following run levels is used to boot a Linux computer in graphical user interface (GUI) mode? A. 3 B. 7 C. 5 D. 9 Answer: C 53. Which of the following commands are used to remove a package from a Linux system? Each correct answer represents a complete solution. Choose two. A. yum -rm packagename B. yum erase packagename C. yum -r packagename D. yum remove packagename Answer: B, D 54. You work as the Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. You are a root user on the Red Hat operating system. You want to view all files with a size of over 50 megabytes on your system. Which of the following commands should you use to accomplish the task? A. find size +50M B. find -size 50M C. find -size -50M D. find -size +50M Answer: D 55. John works as a Network Administrator for Perfect Solutions Inc. The company has a Linux-based network. John is working as a root user on the Linux operating system. He wants to change the group membership of the file foo to group bar. Which of the following commands will he use to accomplish the task? A. chgrp bar foo B. chgroup foo bar C. chgrp foo bar D. chgroup bar foo Answer: A 56. Which of the following files lists the file systems to be mounted automatically at startup? A. /etc/mtab B. /dev/fstab C. /etc/fstab D. /dev/mtab Answer: C 57. Which of the following commands is used to mount file systems? A. detach B. mount C. umount D. attach Answer: B 58. What command will you use to find the current runlevel of an active Linux session? A. runlevel B. init C. rlevel D. ls /etc/runlevel Answer: A 59. Which of the following files contains the names and locations of system log files? A. /etc/lilo.conf B. /usr/syslog.conf C. /etc/syslog.conf D. /usr/lilo.conf Answer: C 60. Which of the following utilities is used to set ACL for files and directories? A. enable acl B. setacl C. setfacl D. getfacl Answer: C RED HAT LINUX SYSTEM ADMINISTRATION Questions and Answers pdf download Read the full article

[thecomputersco]

How to Use the chgrp Command on Linux | TheComputers.Co #computer #technology #pc #tech #software #programmer #thecomputers

[ajo-mathew]

How to Use the chgrp Command on Linux

The chgrp command on Linux changes the group ownership of a file or directory. Why use it instead of chown ? Sometimes a Swiss Army knife is great, but when you really need a scalpel, only a scalpel will do. You use the chgrp command to change the group ownership of a file or directory. from Pocket https://www.howtogeek.com/439500/how-to-use-the-chgrp-command-on-linux/ via IFTTT

[hasnain72]

How to Use the chgrp Command on Linux https://ift.tt/2Nb6sFg

[thelinuxcommandline-blog]

Permissions

Linux systems are not only multitasking systems but also multi-user systems. Means more than one person can be using the computer at the same time.

Commands learned:

id – Display user identity. chmod – Change a file's mode. umask – Set the default file permissions. su – Run a shell as another user. sudo – Execute a command as another user. chown – Change a file's owner. chgrp – Change a file’s group ownership. passwd – Change a user’s password.

Permission Attributes:

chmod - Change file mode Example: chmod 600 foo.txt ‘600′ is an argument in octal number, to set the permissions.

umask - Set default permissions Example: umask 002 (then create a new file, then that file will have permission 002)

su – Run a shell with substitute user and group IDs Usage: su [-[l]] [user], if -l is included, the resulting shell session is a login shell for the specified user. “-l” may be abbreviated “-”. To execute a single command, use su this way: su -c ‘command’.

sudo - Execute a command as another user Usage: sudo command The administrator can configure ‘sudo’ to allow an ordinary user to execute commands as a different user in a controlled way. sudo does not require access to the superuser’s password. sudo does not start a new shell, nor does it load another user’s environment. To see privileged granted by sudo, use sudo -l

passwd: set or change a password Superuser can specify a username as an argument to the above command to set the password for another user.

[timothemauzet]

Vous trouverez dans cette série d'article les principales commandes pour pouvoir utiliser correctement votre système d'exploitation GNU/Linux. Chaque commande est suivie d'une brève description de sa fonctionnalité.