Ans: UNIX is efficient multitasking, multiuser functioning computer operating systems An portable operating system analogous to DOS and Windows, supporting multiple concurrent users. Its portability allows it to run on different hardware platforms.
Ans: Unix is Written in C and assembly language
Ans: Developer involved for Development of UNIX are:
Ken Thompson
Dennis Ritchie
Brian Kernighan
Douglas McIlroy
And Joe Ossanna at Bell Labs
Ans: Shell in UNIX is: Command-line interpreter, which is used to execute Commands entered by user
Users typically interact with a Unix shell using a terminal emulator
In Unix User Directs the Computer by entering commands by text or by creating one or more text scripts of Commands and allow command line interpreter to execute.
Ans: 5 Most Frequently Used Open Source Shells for Linux
Ans: Linux is a UNIX Clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net.It aims towards POSIX The Portable Operating System Interface (POSIX) compliance.
Ans: Solaris is Sun micro systems UNIX.
Ans: Command you use to change the password is“passwd”
Ans: Login Program is responsible to bring the login prompt.
Ans: LILO stands for LInux LOader. LILO is a Linux Boot Loader that loads Linux Operating System into the main memory to begin execution. Most of the computers come with boot loaders for certain versions of Windows or Mac OS. So, when you want to use Linux OS, you need to install a special boot loader for it. LILO is one such boot loader.
When the computer is started, BIOS conducts some initial tests and transfers control to the Master Boot Record. From here, LILO loads the Linux OS and starts it.
The advantage of using LILO is that it allows fast boot of Linux OS.
Ans: The following are a few features of UNIX;
Ans: Generally, UNIX shell commands follow the following pattern
Command (-argument) (-argument) (-argument) (filename)
Ans: The command rm –r * erases all files in a directory with its subdirectories.
Ans: The ls –l command is used to list down files and folders in alphabetical order, sorted with modified time.
Ans: Following the different file types in UNIX;
Ans: Following are the purposes of the given UNIX commands;
Ans: A process ID is a unique integer that UNIX uses to identify a certain process.
The process executes to initiate other processes is called parent process and its ID is defined as PPID (Parent Process ID).
Every process is associated with a specific user and is called the owner of the process. The owner has all the privileges over the process. The owner is also the user who executes the process.
Identification for a user is User ID. The process also associated with Effective User ID which determines the access privileges to accessing resources like files.
Ans: The Kill command accepts process ID (PID) as an in a parameter. This is applicable only for the processes owned by the command executor.
Syntax –kill PID
Ans: The commandmkdir directory_nameis used to create a new directory.
Ans: You can use either pingortelnetto confirm a remote host is alive or not.
Ans: To run a process in the background, nohup is a special command. The process started with this command does not terminate even if the user logs off from the system.
Ans: The UNIX shell serves as an environment to run commands, programs, and shell scripts. In addition to that, it also acts as an interface between the user and the Unix OS. Shell issues $ as the command prompt, which reads input and determines the command to execute.
Ans: Each time you enter a command, a variable named PATH or path will define in which directory the shell will search for that command. In cases wherein an error message was returned, the reason maybe that the command was not in your path, or that the command itself does not exist. You can also manually set the path using the "set path = [directory path]" command.
Ans: One important rule when naming files is that characters that have special meaning are not allowed, such as * / & and %. A directory, being a special type of file, follows the same naming convention as that of files. Letters and numbers are used, along with characters like underscore and dot characters.
Ans: Each logical partitions in Unix are referred to as the File system and each file system contains, a ‘boot block’, a ‘superblock’, ‘inodes’, and ‘data blocks’. The superblock is created at the time of the creation of the file system.
It describes the following:
There are basically two types of superblocks:
26. Enlist some filename manipulation commands in UNIX?
Ans: Some filename manipulation commands along with their description is enlisted below in the table:
| Command | Description |
|---|---|
| cat filename | Displays contents of the file |
| cp source destination | Used to copy source file into the destination |
| mv old name new name | Move/rename and old name to the new name |
| rm filename | Remove/delete filename |
| Touch filename | Changing modification time |
| In [-s] old name new name | Creates soft link on old name |
| Is –F | Displays information about file type |
Ans: To avoid typing long commands or to improve efficiency, the alias command is used to assign another name to a command. Basically, it acts as a shortcut to the larger commands which can be typed and run instead.
For creating an alias in Unix, following command format is used:
alias name=’command you want to run’
Here, replace the ‘name’ with your shortcut command and replace ‘command you want to run’ with the larger command of which you want to create an alias of.
For Example, alias dir ‘Is –sFC’
Here, in the above example, ‘dir’ is another name for the command ‘Is-sFC’. Thus user now simply is required to remember and use the specified alias name and the command will perform the same task as to be performed by the long command.