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Unix
Unix is a family of operating systems primarily designed for servers, mainframes, and high-end workstations. First created in 1969, Unix systems are renowned for their security and stability.
1,127 Questions
Define NFS in operating system?
NFS is the Network File System, and allows directories from systems to be used in other systems in a sharing arrangement.
Why is Unix more portable than other operating systems?
Unix was rewritten in the C programming language and not in assembly language. The migration from assembly language to the higher-level language C resulted in much more portable software, requiring only a relatively small amount of machine-dependent code to be replaced when porting Unix to other computing platforms.
Unix manages the hardware and the executing processes by the kernel. The kernel is a collection of programs written in C which directly communicate with the hardware. applications communicate to system using kernal. Hence kernal need to be changed for different hardware but user interface remains same.
Advantages of buffer cache in unix?
There are several different places that a buffer cache can exist. All have the one thing in common - they are places where data being read from or written to a device is temporarily stored in some medium that is faster than the backing device.
In the case of read caches, a buffer cache can store frequently requested data on a medium that is considerably faster than the underlying device, which speeds up the return of that data to the requesting program. It can also be used to assemble data received out of order (such as from a network interface) into a more presentable form, or can be used to assemble asynchronous data into fixed-size chunks for processing.
In the case of write buffer caches, they are used to smooth out small I/O writes into larger streaming writes (which provides better write performance). They can also be used to assemble smaller bits of information into a larger packet for transmission out a network interface.
Advantages of operating system?
Operating system is a layer between hardware and programs you use (MS Word or so).
So its advantage is that it makes your computer work.
What is a web based operating system?
A web-based OS is a system where all the applications and data his held on the internet. The operating system is essentially like any other operating system except that it runs out of a browser.
Why have GRUB and LILO stayed so popular across all major - nix distros distributions?
GRUB and LILO are easy to configure. With them, you can easily boot multiple operating systems from the same menu on the same computer. To triple boot OS/2, Windows 98, and Windows XP, each operating system needs it's own bootloader, and to manage them all, you need to either install a bootloader that can load them all (Smart Boot Manager, Gujin, GAG, etc...), or mess around with boot sectors. With LILO and GRUB, to boot a compatible *nix system, all it takes is editing a simple text file specifying what partition the operating system's kernel is on, and the name of the kernel, or just chainload to a disk or partition to handle the various Windoze flavors, or other proprietary bootloaders.
Short answer - because they work, and in the 'nix world if it ain't broke. . .
But the new kid on the block - Grub 2 - isn't just an incremental upgrade, quite different in several fundamental ways - most of them IMO improvements. Give a recent Debian-based distro (Ubuntu, Mint) a whirl to check it out and get yourself ready for the future!
Is unix is multiprogramming OS?
Yes, although to use multi-programming effectively your hardware needs to have multiple CPUs.
How do you yank and paste lines in UNIX?
The command 'Y' or 'yy' copies (yanks) one or more lines. To copy one line, two lines, 10 lines, and all lines to the end of the file, respectively:
Y
2Y
10Y
yG
To paste the text contained in the buffer above (uppercase P) or below the current cursor position (lowercase p), respectively:
P
p
It is also possible to yank text within a line. The following commands yank text from the current cursor position to the end of the word and the end of the line, respectively:
yw
y$
The same commands paste the text within a line. Lower case p pastes after the cursor position and upper case P pastes before.
Paste will also work with deleted text, either lines or parts of lines. Be careful not to execute any other commands prior to pasting as this will empty the buffer.
Write an algorithm for Round Robin CPU scheduling using?
On each system clock tick, at interval set by design...
- If no other runnable threads, return from clock interrupt.
- Save the currently running thread's context.
- Restore the next runnable thread's context.
- Return from clock tick interrupt.
Note: Most modern schedulers combine round-robin with priority. In the priority scheme, any runnable thread with a higher priority than the interrupted thread takes precedence. If there are none, then round-robin applies at the current priority. If there are no runnable threads at the current priority, lower priorities are considered until we reach the idle priority thread, which, by the way, is always runnable.
Also, there is usually an algorithm that adjusts thread priority dynamically. As the thread runs, if it stays runnable its priority slowly drops from its initial base priority. If it is constantly blocking and then then becoming runnable, its priority increases, often faster than it decreases. This makes interactive threads appear to be very responsive, while CPU intensive threads slowly defer to interactive threads. This is usually a good compromise between responsiveness and throughput.
What is the difference between sed and awk?
They both are frequently used programs in UNIX, but they do different things. Read their manuals if you want to use them.
vi is the default editor in Linux operating systems. It can be used not just to write programs, but to write any type of text files. Refer the following link for complete set of commands.
http://www.cs.colostate.edu/helpdocs/vi.HTML
Difference between Kernel mode and User mode in Operating System?
bt.o is the kernel mode driver. When you insmod bt.o you are inserting it into the kernel, where it can cause bad things to happen if it screws up. btduser is the user mode driver. It runs as an application in user space, where usually the worse thing that can happen is a segfault. You don't have to insmod anything for user mode. You just run the application.
Why unix is an open source operating system?
Unix is NOT open source, it is proprietary copyrighted code owned by AT&T and you must purchase a license to use it, as you do on Windows and Mac OS X.
However both Linux and GNU are open source OSs with equivalent functionality to Unix.
FreeBSD® is an advanced operating system for x86 compatible (including Pentium® and Athlon™), amd64 compatible (including Opteron™, Athlon™64, and EM64T), UltraSPARC®, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX® developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.
This text is from FreeBSD homepage.
www.freebsd.org
Why do some describe Unix as the most flexible operating system?
*NIX (Which includes Unix, Xenix, Linux, HPUX, etc.) offers flexibility because of a number of factors.
o Journaled file system - allows for better data stability
o Greater security
o Greater scalability
o Included compilers
o Included source code
o Compatibility with other file systems
o Piped commands
If you try the command 'man sed' you see it is listed as one of the examples of what sed can do.
What is the difference between line and stream editors?
A line oriented editor uses navigation and other means by line numbers. When you print a line, move to a line, or change something in a line all that is shown is the line itself, and not with the context of what is being changed.
Line oriented editors were common when screen or page based editing was not available. These days most text editors will show at least a half to full page of where you are editing so you see the change in context.
How to start ntp services on Sun Solaris 8?
To activate the ntp
server try the following command:
# svcadm
enable svc:
/network/ntp:default
After that check if the service is running:
# svcs
-a | grep ntp
# PS -ef
| grep ntp
The above answer applies to Solaris
10 and 11, but not to Solaris
8.
Solaris
8 does NOT include an NTP program as part of the default OS distribution. However, there are several freeware packages which can be used to install it.
To start such an NTP program, use the following command (run as root):
/etc/init.d/ntpd start
Why is Unix called a command interpreter?
Unix and Unix-like systems would be referred to as command interpreters because of the nature of their interface. These systems are interacted with via a shell (i.e. Bash), which is a 'command-line interface' where the user types in text commands and they are executed by the system. This is in contrast with modern operating systems where the primary method of interaction is via a 'graphical user interface' or GUI, where the system is represented with graphics (like windows, cursors, toolbars etc.). These modern OS's still include command-line interfaces, like Command Prompt in Windows and the Terminal in OSX.
UNIX is an open source operating system. As natural for an OS, it has its own way of doing all the tasks it is supposed to do- like managing files, allocating resources, handling user accounts- so on and so forth. These features make working on UNIX a different experience to working on Windows or Mac OSx- just like the experience of Windows is dissimilar to the OSx experience.
Keeping this in mind, the platform and the tools UNIX offers is collectively known as the UNIX environment.
Which tool allows you to interact with the operating system via a text interface?
Many Unix and Linux servers come without a graphical user interface, and the text mode interface is the default.
For those systems using a GUI, there is a 'terminal' tool that you can select from the menu to allow text interactions.
Upgrading an outdated computer system would be an example of which of these?
increasing the value of capital goods
fast
