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What is Linux
23 Apr 2020

Linux

What is Linux?

Linux is a family of open-source Unix-like operating systems based on the Linux kernel invented by Linus Torvald in 1991.

Linux was designed to be similar to UNIX, but has evolved to run on a wide variety of hardware from phones to supercomputers. Every Linux-based OS involves the Linux Kernel which manages hardware resources and a set of software packages that make
up the rest of the operating system.

What Does Linux Include?

1. Kernel :

The base component of the OS. Without it, the OS doesn’t work. The kernel manages the system’s resources and communicates with the
hardware. It’s responsible for memory, process, and file management.

2. System User Space :

When you open an application, the OS loads the program and required resources into the userspace. Any required libraries are loaded into the user space as well. If you open and edit a document, that file will also be temporarily loaded into the userspace. When you save the file, the data is written from the user space to a storage device such as an HDD or SDD.

3. Application :

Application software is a program or group of programs designed for end-users. These programs are divided into two classes: system software and application software. While system software consists of low-level programs that interact with computers at a basic level, application software resides above system software and includes applications such as word processors and spreadsheet.

 

Linux Commands

Widely Used Commands In Linux :

  • System Information :
    • cat /etc/redhat-release
    • Uptime
    • Hostname
  • Hardware Information :
    • Cat /proc/cpuinfo (CPU)
    • Free -h (shows free or used memory)
    • dmidecode
  • Performance Monitoring :
    • Top (shows all runtime processes)
    • Ls /var/log/messages
  • User Management :
    • Useradd “name of user”
    • Usermod (for any modification)
    • Cat /etc/passwd (user related information)
    • Cat /etc/shadow (password related information of users)
  • File Permission :
    • Chmod 777 filename
    • Setfacl -m u:xxx:rwx filename
  • Networking :
    • Ifconfig
    • Ping hostname
    • Firewall-cmd –add-port/services