Linux and Unix are important topics in Operating System for IBPS SO IT Officer preparation. Questions can be asked from Linux commands, Unix architecture, file permissions, process management, shell commands, networking commands, and basic system administration. A good understanding of Linux and Unix helps students solve both theoretical and command-based questions in the Professional Knowledge section.
Table of Contents
What is Unix?
Unix is a powerful, multi-user and multitasking operating system. It was designed for stability, security, portability, and command-line-based operation. Unix is mostly used in servers, workstations, enterprise systems, and large computing environments.
Unix introduced many important operating system ideas such as hierarchical file system, pipes, shell scripting, process control, and the concept that everything is treated as a file.
What is Linux?
Linux is an open-source Unix-like operating system. It is based on the Linux kernel and is widely used in servers, cloud computing, cybersecurity, software development, networking, embedded systems, and supercomputers.
Linux is free to use, modify, and distribute. Popular Linux distributions include Ubuntu, Debian, Fedora, Red Hat Enterprise Linux, Kali Linux, Arch Linux, and openSUSE.
Linux vs Unix
Linux and Unix are similar in many ways, but they are not exactly the same. Unix is an older operating system family, while Linux is a Unix-like operating system developed later as an open-source alternative.
Basis Linux Unix Nature Open-source Unix-like operating system Original operating system family Cost Mostly free Mostly proprietary Source Code Available to the public Usually not freely available Examples Ubuntu, Fedora, Debian, Kali Linux, Red Hat AIX, Solaris, HP-UX Usage Servers, desktops, cloud, cybersecurity, development Enterprise servers and workstations Flexibility Highly flexible and customizable Less flexible compared to Linux
Similarities Between Linux and Unix
Linux and Unix both support multi-user operation, multitasking, command-line interface, hierarchical file system, file permissions, process management, pipes, redirection, and shell scripting.
Architecture of Linux and Unix
The architecture of Linux and Unix mainly consists of hardware, kernel, shell, system utilities, and user applications.
Component Meaning Exam Importance Hardware Physical components like CPU, memory, disk, keyboard, and monitor Basic OS layer Kernel Core part of the operating system that manages resources Very important Shell Command interpreter between user and kernel Very important System Utilities Programs used for file management, process control, and system tasks Important for command questions User Applications Software used by users Basic understanding required
Kernel
The kernel is the heart of the operating system. It manages CPU, memory, files, devices, processes, and system calls. It acts as a bridge between hardware and software.
The main functions of the kernel are process management, memory management, device management, file system management, and system call handling.
Shell
The shell is a command interpreter. It takes commands from the user, interprets them, and passes them to the kernel for execution. Common shells include sh, bash, csh, ksh, and zsh.
For IBPS SO IT, remember that Bash is one of the most commonly used shells in Linux.
Linux File System
Linux and Unix use a hierarchical file system. The top-level directory is called the root directory and is represented by /. All files and directories are placed under this root directory.
In Linux, everything is treated as a file. Regular files, directories, devices, and processes are represented in file-like form.
Important Linux Directories
Directory Use / Root directory of the Linux file system /home Stores user home directories /bin Contains essential user commands /sbin Contains system administration commands /etc Contains system configuration files /var Contains variable data such as logs and cache /tmp Stores temporary files /usr Contains user programs and libraries /dev Contains device files /proc Contains process and kernel information
Important Linux Commands for IBPS SO IT
Linux commands are very important for IBPS SO IT because many questions are directly based on command usage. The following table covers the most useful commands for revision.
Command Use Example pwd Shows present working directory pwd ls Lists files and directories ls -l cd Changes directory cd /home mkdir Creates a new directory mkdir test rmdir Removes an empty directory rmdir test touch Creates an empty file touch file.txt cat Displays file content cat file.txt cp Copies files or directories cp a.txt b.txt mv Moves or renames files mv old.txt new.txt rm Removes files or directories rm file.txt man Shows manual page of a command man ls
File Viewing Commands
Command Purpose cat Displays complete file content less Views file content page by page more Views file content page by page head Displays the first few lines of a file tail Displays the last few lines of a file tail -f Monitors file changes in real time, commonly used for logs
File Permissions in Linux and Unix
File permission is one of the most important Linux topics for IBPS SO IT. Linux uses three basic permissions: read, write, and execute.
Permission Symbol Numeric Value Meaning Read r 4 Allows reading file content or listing directory content Write w 2 Allows modifying file content or changing directory content Execute x 1 Allows executing a file or entering a directory
Permission Categories
Linux permissions are given to three categories: owner, group, and others. Owner means the user who owns the file. Group means users who belong to the same group. Others means all remaining users.
Common chmod Values
chmod Value Permission Meaning Common Use 777 Read, write, execute for everyone Generally not recommended for security 755 Owner has full permission; group and others have read-execute Common for directories and executable files 644 Owner has read-write; group and others have read-only Common for normal files 600 Owner has read-write only Used for private files
Important Permission Commands
chmod is used to change file permissions.
chown is used to change file ownership.
chgrp is used to change group ownership.
umask defines default permissions for newly created files and directories.
Process Management in Linux and Unix
A process is a program in execution. Linux and Unix support multitasking, so multiple processes can run at the same time. Every process has a unique Process ID called PID.
Command Use ps Displays currently running processes top Displays real-time process information kill Terminates a process using PID killall Terminates processes by name bg Sends a process to the background fg Brings a background process to the foreground jobs Displays background jobs
Types of Processes
A foreground process runs directly in the terminal and waits for user interaction. A background process runs behind the terminal and allows the user to continue other work. A daemon process runs in the background and provides system services.
Important System Calls
System Call Use fork Creates a new process exec Replaces current process with a new program wait Makes parent process wait for child process exit Terminates a process
Pipes and Redirection
Pipes and redirection are important command-line concepts in Linux and Unix. A pipe sends the output of one command as input to another command. The pipe symbol is |.
Example: ls | grep test
This command displays files whose names contain the word test.
Symbol Meaning Example | Pipe output of one command to another ls | grep file > Redirect output and overwrite file ls > files.txt >> Redirect output and append to file echo Hello >> notes.txt < Take input from file wc -l < file.txt
Searching and Filtering Commands
Command Use grep Searches text patterns inside files find Searches files and directories locate Quickly finds files using a database sort Sorts data uniq Removes duplicate adjacent lines wc Counts lines, words, and characters cut Extracts specific columns from text awk Used for text processing and pattern scanning sed Used for stream editing and text replacement
Networking Commands in Linux
Linux networking commands are important for IT Officer preparation because banking systems depend heavily on servers, networks, and secure communication.
Command Use ping Checks network connectivity ip addr Displays IP address and network interface details ifconfig Displays network interface information netstat Displays network connections ss Displays socket statistics traceroute Shows the route taken by packets nslookup Performs DNS lookup dig Performs detailed DNS queries ssh Provides secure remote login scp Securely copies files between systems wget Downloads files from the internet curl Transfers data from or to a server
Linux Security Concepts
Linux is widely used in servers because it provides strong user permissions, file ownership, process isolation, access control, and security updates.
Root User
The root user is the superuser in Linux and Unix. It has complete control over the system. Since root has full administrative power, it should be used carefully.
sudo Command
The sudo command allows a permitted user to run commands with administrative privileges. It is safer than directly logging in as root because it provides temporary administrative access.
Important Security Files
File/Directory Purpose /etc/passwd Stores user account information /etc/shadow Stores encrypted password information /etc/group Stores group information /var/log Stores system log files
Cron and Scheduling
Cron is used to schedule tasks in Linux and Unix. It allows commands or scripts to run automatically at fixed times. The crontab command is used to manage cron jobs.
Environment Variables
Environment variables store system and user-level configuration values. PATH is one of the most important environment variables. It tells the shell where to search for executable commands.
Command Use echo $PATH Displays the PATH variable export Creates or modifies environment variables env Displays environment variables
Hard Link and Soft Link
A hard link is another name for the same file on disk. It points directly to the inode of the file. A soft link, also called a symbolic link, points to the file path. If the original file is deleted, a soft link may become invalid, but a hard link can still access the data if the inode exists.
Basis Hard Link Soft Link Points To Inode File path Original File Deleted Data may still be accessible Link becomes broken Across File Systems Usually not allowed Allowed Directory Link Generally not allowed for normal users Allowed
Inode
An inode is a data structure that stores metadata about a file. It contains information such as file permissions, ownership, size, timestamps, and disk block location. The file name is not stored inside the inode.
Shell Scripting
Shell scripting means writing a group of shell commands in a file and executing them together. Shell scripts are used for automation, backup, monitoring, system administration, and repetitive tasks.
Shell scripts can use variables, loops, conditional statements, functions, command-line arguments, and input-output operations.
Linux Boot Process
The Linux boot process generally includes BIOS or UEFI, bootloader, kernel loading, init or systemd, and user login. BIOS or UEFI initializes hardware. The bootloader loads the kernel. The kernel initializes system resources. systemd starts services. Finally, the user gets a login screen or terminal.
GRUB
GRUB stands for Grand Unified Bootloader. It is a bootloader used in many Linux systems to load the operating system kernel during the boot process.
Package Management
Package managers are used to install, update, and remove software in Linux. Different Linux distributions use different package managers.
Package Manager Used In apt Debian and Ubuntu-based systems yum Older Red Hat and CentOS-based systems dnf Fedora and newer Red Hat-based systems pacman Arch Linux zypper openSUSE
Linux and Unix in Banking IT
Linux and Unix are widely used in banking and enterprise environments because they are stable, secure, reliable, and suitable for server-based applications. Banking systems require strong security, high availability, process control, user management, log monitoring, and network services. This makes Linux and Unix knowledge useful for IT Officer roles.
Important IBPS SO IT Exam Points
Topic Must Remember Point Linux Linux is an open-source Unix-like operating system Unix Unix is multi-user and multitasking Kernel Kernel is the core of the operating system Shell Shell is a command interpreter Root Directory The root directory is represented by / chmod Changes file permissions chown Changes file ownership ps Displays process information kill Terminates a process grep Searches text patterns cron Schedules tasks sudo Runs commands with administrative privileges PATH Stores command search paths GRUB Bootloader used to load the kernel
Common Mistakes Students Make
Many students only memorize Linux commands but do not understand their purpose. For IBPS SO IT, students should understand both command usage and operating system concepts behind them.
Another common mistake is confusion between chmod and chown. chmod changes permission, while chown changes ownership.
Students also confuse shell and kernel. The kernel manages system resources, while the shell accepts user commands and passes them to the system for execution.
How to Prepare Linux and Unix for IBPS SO IT
First, understand the basic architecture of Linux and Unix. Then learn important directories, basic commands, file permissions, process commands, networking commands, and shell scripting basics. After that, revise command tables and practice MCQ-based questions.
For better preparation, make short notes of commands and their uses. Focus more on commands like chmod, chown, ps, kill, grep, find, tar, cron, ssh, ping, and sudo because these are commonly useful in exam-style questions.
Conclusion
Linux and Unix are important parts of Operating System preparation for IBPS SO IT. Students should focus on architecture, kernel, shell, file system, commands, permissions, process management, networking, security, cron jobs, and shell scripting. Regular revision of command tables and exam points can help students score better in the Professional Knowledge section.
Frequently Asked Questions on Linux and Unix
What is Linux?
Linux is an open-source Unix-like operating system widely used in servers, cloud computing, networking, cybersecurity, and software development.
What is Unix?
Unix is a multi-user and multitasking operating system known for stability, security, and command-line operation.
What is the main difference between Linux and Unix?
Unix is an older operating system family, while Linux is an open-source Unix-like operating system. Unix is mostly proprietary, while Linux is freely available.
What is the role of the kernel?
The kernel manages hardware resources, memory, files, devices, processes, and system calls.
What is the role of the shell?
The shell is a command interpreter that allows users to interact with the operating system by typing commands.
Which Linux commands are important for IBPS SO IT?
Important Linux commands include ls, cd, pwd, cat, cp, mv, rm, chmod, chown, ps, top, kill, grep, find, ssh, ping, tar, and cron-related commands.
Is Linux important for IBPS SO IT?
Yes, Linux and Unix concepts are important because they are part of Operating System and system administration topics in IT Professional Knowledge preparation.
What is chmod used for?
chmod is used to change file permissions in Linux and Unix.
What is chown used for?
chown is used to change the ownership of a file or directory.
What is cron used for?
Cron is used to schedule commands or scripts to run automatically at specific times.