#Command Line Interface

Unix/Linux

Unix is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, development starting in the 1970s at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others

Part 1: Ubuntu Users and Groups

Linux is a multi-user operating system. This means multiple people can be logged in and working on the same system simultaneously, and the system needs a way to differentiate their access.

1. Types of Users

Root User (Superuser):

The King/Queen: This is the most powerful user account (root). It has absolute, unrestricted access to the entire system.

UID 0: The root user always has a User ID (UID) of 0.

Bread and Butter Commands - all important

• This article provides practical examples of most frequently used commands in Linux/UNIX.

man - Super Important
cd ( Understand flags - dot ., double dot .., tilda~, dash -)
mkdir, mv
cp with recursive flag
ls with different flags
pwd, rm, sudo, apt
touch, cat, less, more
tail, rsync, grep
find - Super Important
sort, date, wc
tree (needs to be installed additionally)

Unix Intermediate commands

• lsof, kill, ifconfig
• chmod wget
• who whois
• Print user detail

# users name
who

# time of last system boot
who -b

Some Advance unix commands

• crontab, tail, Screen, grep, compress, wc

CRONTAB

• The crontab is a list of commands that you want to run on a regular schedule

# Shows all Crontab
crontab -l

# Edit Crontab
crontab -e

# Remove all cron tab --> Be careful
crontab -r

Command Line Basics Crash Course

Video - https://www.youtube.com/watch?v=cBokz0LTizk

Given above is a quick super-fast course in using the command line. It is intended to be done rapidly in about a day, and not meant to teach you advanced shell usage.