Keywords: Kernel, Shell, Terminal, Console, Command Line,
Scripting, Skills, Tools
· Key Terminologies
o Kernel
ü
a computer program at the
core of a computer operating system that always has complete control over
everything in the system.
ü
It manages the following
resources: File management, Process management, I/O management, Memory
management, Device management, etc.
o Shell
ü
A shell is a special user
program that provides an interface for the user to use operating system
services
ü
Shell accepts
human-readable commands from users and converts them into something which the
kernel can understand
ü
It is a command language
interpreter that executes commands read from input devices such as keyboards or
from files. The shell gets started when the user logs in or starts the
terminal.
ü
Shell is broadly classified
into two categories: Command Line Shell, Graphical shell
ü
Shell can be accessed by
users using a command line interface. A special program called Terminal in
Linux/macOS, or Command Prompt in Windows OS is provided to type in the
human-readable commands
ü
Graphical shells provide
means for manipulating programs based on the graphical user interface (GUI), by
allowing for operations such as opening, closing, moving, and resizing windows,
as well as switching focus between windows
ü
Window OS or Ubuntu OS can
be considered as a good example which provides GUI to the user for interacting
with the program. Users do not need to type in commands for every action.
ü
Several shells are
available for Linux systems like SH (Bourne shell), BASH (Bourne
again shell), CSH (C-shell), KSH (Korn shell), Each shell does
the same job but understands different commands and provides different built-in
functions
o Terminal
ü
A program which is
responsible for providing an interface to a user so that he/she can access the
shell.
ü
It basically allows users
to enter commands and see the output of those commands in a text-based
interface.
ü
Large scripts that are
written to automate and perform complex tasks are executed in the terminal.
o Terminal vs Console vs Shell vs Command Line
ü
Terminal, Console, Shell,
and Command line all are ways to give the command to the computer but all these
have different functions.
ü
A terminal is a text-based
interface that is used to type commands or take input and view the output. Examples:
Command prompt, guake, gnome-terminal, terminator, etc.
ü
A console is a type of
terminal that is used to interact with operating system programs. Examples: Famicom,
Xbox, PlayStation, Nintendo Switch, Wii, and Wii U, etc.
ü
Shell is used to interact
with the operating system’s kernel. It interprets and processes the commands
entered by the user. Examples: Bash, zsh, ksh, sh, tsch, Power Shell, pwsh, cmd,
yori, etc.
ü
The Command Line is an area
where the user enters the commands. Examples: Microsoft Windows, DOS Shell,
Mouse Systems Power Panel, etc.
· Shell Scripting
o
Usually, shells are
interactive, which means they accept commands as input from users and execute
them.
o
However, sometimes we want
to execute a bunch of commands routinely, so we have to type in all commands
each time in the terminal.
o
As a shell can also take
commands as input from file, we can write these commands in a file and can
execute them in shell to avoid this repetitive work. These files are
called Shell Scripts or Shell Programs.
o
Shell scripts are similar
to the batch file in MS-DOS. Each shell script is saved with ‘.sh’ file
extension e.g., myscript.sh.
o
A shell script has syntax
just like any other programming language.
o
A shell script comprises
the following elements Shell Keywords, Shell commands, Functions, Control flow,
etc.
· Shell Scripting Skills:
o Technical Skills Integration
ü
Proficiency in Scripting
Languages
ü
Proficiency in Command Line
Operations
ü
System Administration and
Configuration
ü
Task Automation
ü
Integration with DevOps
Practices
ü
Continuous Integration/Continuous
Deployment (CI/CD)
ü
Configuration management
o Soft Skills
ü
Efficiency and Automation
ü
Problem-Solving and
Troubleshooting Abilities
· Shell Scripting Tools
o
Operating Systems:
Unix, Linux, Windows, MacOs
o Shell: Bash, zsh, ksh, sh, tsch, Power Shell, pwsh, cmd,
yori, etc.
o Terminals: Command prompt, guake, gnome-terminal, terminator,
etc.
