Basic Interview Questions in Unix

What is Unix?
Unix is a robust, multitasking and multi-user operating system developed at Bell Labs in the late 1960s. It's renowned for its portability, reliability, and flexibility and has served as the foundation for various other operating systems.

What is a shell?
A shell is a software program that enables users to interact with the Unix operating system. Essentially, it functions as a command interpreter that reads and executes user input.

What are some common shells in Unix?
Common shells in Unix include bash, csh, ksh, zsh, and sh.

What is the process in Unix?
A process in Unix is a currently executing program or task on the system. Each process is assigned a unique Process ID (PID) to facilitate system tracking.

What is a daemon in Unix?
A daemon is a specific type of process that operates in the background, handling various tasks such as managing system resources or providing network services.

What is a file in Unix?
In Unix, a file is a data collection stored on disk or other storage media, coming in various types like text files, binary files, directories, or device files.

What is a directory in Unix?
A Unix directory is a file that maintains a list of other files and directories, similar to a folder in Windows.

What is a permission in Unix?
Unix employs a permission system to regulate access to files and directories. It involves three types of permissions: read, write, and execute, which can be configured for the file's owner, the file's group, and all other users.

What is a pipeline in Unix?
A Unix pipeline is a method for linking multiple commands so that the output of one command serves as the input for the next command.

What is a wildcard in Unix?
A wildcard in Unix is a character used to represent one or more other characters. Common wildcards include the asterisk (*) and question mark (?), which respectively match any string of characters or a single character.

What is the distinction between a hard link and a symbolic link in Unix?
A hard link directly references a file on a disk, while a symbolic link is a specialized file that points to another file or directory.

What is the root directory in Unix?
The root directory represents the top-level directory in the Unix file system hierarchy and is denoted by the forward-slash (/) character.

What is the distinction between a relative path and an absolute path in Unix?
A relative path is specified about the current working directory, while an absolute path begins at the root directory, specifying the complete path to the file or directory.

What is the purpose of the grep command in Unix?
The grep command is utilized to search for text patterns within files. It can search for patterns in a single file or conduct recursive searches throughout multiple files and directories.

What is the purpose of the find command in Unix?
The find command is employed to locate files and directories on a Unix system that match specific criteria, such as file name, size, or modification time.

What is the purpose of the chmod command in Unix?
The chmod command is used to modify the permissions of files and directories, enabling the setting or alteration of read, write, and execute permissions for the owner, group, and other users.

What is the purpose of the chown command in Unix?
The chown command is employed to change the owner and group of files and directories, facilitating the transfer of ownership between users or the assignment of group ownership to files.

What is a shell script in Unix?
A shell script is a file comprising a sequence of Unix commands that can be executed consecutively as a single program. Shell scripts are frequently employed to automate repetitive tasks or undertake complex system administration duties.

What is the purpose of the tar command in Unix?
The tar command serves to generate and manipulate archives of files and directories. It can combine multiple files into a single archive or extract files from an archive.

What is the purpose of the top command in Unix?
The top command provides real-time information regarding the currently running processes on a Unix system, making it valuable for system performance monitoring and problem diagnosis.