Working with Linux CLI #2

Working with Linux Command Line Interface #2
https://msslinux.blogspot.com/2020/07/working-with-linux-cli-2.html

Login: student
 pass: ******

 [student@hostX Desktop]$ su
  Password: ******

 [root@hostX ~]# exit
 [student@hostX ~]$ exit

Linux Command Syntax/Pattern/structure:
===============================

Ideally every command has three parts. At first Command which is mandatory and last one is argument. Some commands works without arguments and for some commands arguments are mandatory. There is another part found for some commands tat is options.

  # command [optoin (-)] argument

 ex # ping -c 6 172.25.10.135   //'ping'(command) '-c 6'(option) '172.25.10.135' (argument)
    # date  //no option no argument
    # cal


[student@hostX Desktop]$ cd
[student@hostX ~]$ ls      ;list of files and dir.
[student@hostX ~]$ ls -l
[student@hostX ~]$ ls -li  ; Files and directory inode
[student@hostX ~]$ ls -la  ; details list with hidden files and dir
[student@hostX ~]$ ls -lh  ; human readable
[student@hostX ~]$ ls -laih ; all


here let's discus about different options of 'ls' command:

 -l = list  (to show long and details list as option)
 -i = inode (unique indexing number for every file)
 -a = all   (will show all files including hidden files of current directory )
 -h = human readble (will show file size in Kilo, Mega, Giga instead of bytes)


Continued in next post Working with Linux CLI #3

Working with Linux CLI #1

Working with Linux Command Line Interface #1
https://msslinux.blogspot.com/2020/07/working-with-linux-cli-1.html

Very Introductory orientation of Linux Command Line based on Red Hat Enterprise  Linux 8 (RHEL8). Throughout the series  of tutorial learner will get familiar with Linux CLI from zero to hero. No prior knowledge is required.


Linux Command Line Interface Orientation:
===============================
[student@hostX Desktop] $
[root@hostX    Desktop] #
  1         2               3         4

  1: user id
  2: host name
3: user's current location
4: user types (root: #, regular user: $)

Linux User's Types:
===============
 => root user: Administrator (#)
 => system user: service (mail/ftp/games/daemon)-cannot login
 => regular user: student, guest, sam,bob ($)


Working with Linux Shells & Terminal:
=============================
 User -> Keyboard -> Terminal/Application -> Shell -> Kernel -> Hardware
           Screen <- Terminal <- Shell <- Kernel <- Hardware

Which Shells are in use and which shells are available in current system:

[student@hostX Desktop] $ echo $SHELL
[student@hostX Desktop] $ chsh -l
 /bin/sh
 /bin/bash
 /usr/bin/sh
 /usr/bin/bash


Continued in next post Working with Linux CLI #2

WHAT IS FIRMWARE? AND WHAT IS KERNEL?

WHAT IS FIRMWARE? AND WHAT IS KERNEL?
https://msslinux.blogspot.com/2020/07/what-is-firmware-and-what-is-kernel.html
Firmware is software that typically exists on a microchip device. Your PC's BIOS is one example.
The simple (Basic Input Output System, BIOS) program that runs every time you turn on your PC scans/communicates with your CPU, RAM, video card, hard drives,
 floppy drives, USB controller, etc. Since the program is stored (and run) on a chip, it's called "firm"ware, whereas "soft"ware is loaded from
 a flexible source (a hard drive) and typically run on a general purpose processor (your computer's CPU).

A kernel is a (mid-level) piece of software that interfaces between applications and the PC's hardware.
 It's not as low-level as firmware (which often runs ON the hardware, itself); nor is it a high-level program like a user program (word processor,
spreadsheet app, browser, etc). Unlike firmware, the kernel is software, as it gets loaded into memory when a PC boots from
the hard drive (it's one of the first things to get loaded and executed).