The UNIX operating system is a set of programs that perform as a link between the computer and the user.
The computer program that allocates the system resources and coordinates all the information of the computer's internal is called the operating system or the kernel.
Users correspond with the kernel through a program known as the shell. The shell is a command line performer; it translates commands entered by the user and converts them into a language that is understand by the kernel.
Here is a basic block illustration of a UNIX system −
The most important concept that unites all the versions of UNIX is the following four fundamentals −
If you have a computer which has the Unix operating system install in it, then you only want to turn on the system to make it live.
As soon as you rotate on the system, it starts booting up and at last it prompts you to log into the system, which is a movement to log into the system and use it for your day-to-day performance.
When you first attach to a UNIX system, you generally see a prompt such as the following –
You will be provide with a command without delay (sometime called the $ prompt) where you kind all your commands. For instance, to check calendar, you need to kind the cal command as follows –
All UNIX systems want passwords to help certify that your files and data stay on your own and that the system itself is secure from hackers and crackers. Following are the steps to modify your password −
Step 1 − to begin, type password at the command prompt as exposed below.
Step 2 − Enter your old password, the one you're presently using.
Step 3 − Type in your new password. Always keep your password difficult enough so that nobody can guess it. But make sure, you consider it.
Step 4 − you must validate the password by typing it again.
Note − we have added asterisk (*) here just to explain the location where you need to enter the recent and new passwords otherwise at your scheme. It does not show you any character when you nature.
All data in UNIX is prepared into files. All files are organized into directories. These directories are organized into a tree-like constitution called the file system.
You can apply the less command to list out all the files or directories accessible in a directory. Following is the instance of using less command with -l selection.
Here entry starting with d..... Stand for directories. For instance, ump, unit and urlspedia are directories and rest of the entry are files.
While you're logged into the scheme, you might be willing to know: Who am I?
The easiest way to find out "who you are" is to penetrate the whom command –
Try it on your system. This command lists the account name connected with the present login. You can try who am icommand as well to get information about yourself am.
Sometime you strength be concerned to know who is logged in to the computer at the same time.
There are three commands obtainable to get you this in order, based on how much you wish to know about the other users: users, who, and w.
Try the w command on your system to check the output. This list down information connected with the users logged in the system.
When you send your session, you need to log out of the system. This is to make sure that nobody else access your files.
The most regular way to shut down a UNIX system correctly via the command line is to use one of the following commands –
|S.No.||Command & Description|
You normally need to be the super user or root (the most privileged account on a UNIX system) to shut down the system. Still, on some separate or personally-owned UNIX boxes, a directorial user and sometimes standard users can do so.
Unix/Linux Related Interview Questions
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