Linux contd

Applications in Linux

• To run any application, every os will create a process with a unique id with cpu & ram allocated
• on a broader note we run applications as
  • executables:
    • The process is created when you run the command or application
  • daemons/service:
    • This runs in the background, typically all servers on os are daemons
    • daemons can be started automatically when the system starts (Enabling the service)
    • In all modern linux we use systemctl command to control daemons.

How to get the applications installed in linux

• Build from source code.
  • Refer Here for an example
• Debian/rpm packages:
  • use dpkg or rpm commands
• Package Manager (apt/dnf)
  • Lets install tree

What happens when linux Starts

• BIOS (UEFI)
• Bootloader (GRUB)
• kernel => memory
• init service => Process with id 1
• PID => other process (load daemons)
  

Users/Groups in Linux

• Find out what is the purpose of
  • sudo group: This is group which can run sudo commands for elevated privleges in debian
  • wheel group: This is group which can run sudo commands for elevated privleges in redhat based distributions
• What is home directory: is the directory where the user has permissions, typically /home/<username>
• Every linux system has a root user with permission on everything.

Folder structure in linux

• File structure