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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
Unix (officially trademarked as UNIX®, sometimes also written as Unix or Unix® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy.
It is important because counting all of the various flavors of UNIX (freeBSD, openBSD, Solaris, HP-UX,etc. also sort of Mac OS-X) and all of the Linux Flavors (which are sort of descendants of UNIX systems) would make up a large portion of all of the computers in operation.
Unix is important in and of itself because it was designed to handle multiple stations connecting to a central hub which, in turn, may itself be connected to other hubs. This defines a network with a star topology which, amazingly enough, is the same as the basic structure of the entire internet.
In a nut shell UNIX is an operating system which at one point in time, was the most prevalent operating system in use. It is still widely used in scientific and professional circles. Unix is one of the oldest but still most popular Operating Systems. It was invented in 1969 at AT&T Bell Labs by Ken Thompson and Dennis Ritchie. All the contemporary operating systems of Solaris, HP-UX, Linux, AIX are variants of Unix. Unix is a family of multi-user operating systems. It was originally developed by AT&T in the 1970s. Unix has a very strong security and model and relatively simple design, making it popular and fairly easy to implement. Many operating systems are either based on or modeled after the first Unix systems, such as Linux, Solaris, or Mac OS X.
What is the difference between RSH and SSH?
rsh and ssh are similar in that they can execute commands on remote systems. The main difference between the two (besides the actual TCP ports) is that rsh traffic is not encrypted and therefore a security risk; ssh traffic is encrypted.
The other main difference is that ssh is a secure replacement for telnet, whereas rsh can log into a remote system using the rlogin protocol, which is similar but not the same as telnet.
How do you move to your home directory using a relative path name?
There are several ways to do this. The easiest way is just to type the command 'CD', which automatically puts you in your home directory. Other ways:
CD $HOME
CD ~
CD ~login-id (use your login-id here)
If you know the absolute path name, just use it with the 'CD' command:
CD /home/staff/guy1
There are several ways to do this (typical Unix ...).
you could execute the following command:
du | sort -n | tail -6
The 'du' command lists disk usage by listing a file name and size per line, then use the sort command to list numerically, and the last 6 will be the 6 largest.
What is the difference between echo cat and cat echo commands in Linux?
echo cat will print out the word 'cat' on the command line.
cat echo will attempt to list the contents of a file called 'echo'.
A "pipe" is where output is redirected to another program. It exists in Windows as well as Unix (although you don't see much of it in Windows usage).
The character used in piping is the pipe character ('|').
For example, you wanted to create a MD5 hash of the message "Hello World!" you'd do echo "Hello World!" | md5sum. The echo command will output "Hello World" to standard output (also called stdout), and the pipe will redirect that to the md5sum utility, which will calculate the MD5 hash from the output as input.
POSIX stands for Portable Operating System Interface for UniX. It is an IEEE 1003.1 standard that defines the language interface between application programs and the Unix operating system. Adherence to the POSIX ensures compatibility when programs are moved/migrated from one unix computer to another.
AnswerStrictly speaking, POSIX is an API specification, in conjunction with a specification of certain specific utility programs which must be present. While originally based on the UNIX Operating System, POSIX does not have to mean a UNIX system. For example, both certain versions of Windows NT and IBM's OS/360 have received POSIX certification as complying with the specification.As noted above, POSIX is about insuring compatibility of programs between systems, allowing a POSIX-compliant program to run on any POSIX-compliant Operating System.
there is an open-source project based on a heavily modified and specialized Unix code-base, this is called OpenSolaris from Sun Microsystems but this was discontinued when Oracle acquired Sun
however the open-source efforts has continued with an OpenSolaris fork called OpenIndiana and similar distributions based on the illumos kernel which remains theonly available open-source descendant of the UNIX System V, Release 4 (SVR4) code base developed by Sun and AT&T in the late 1980s..
OpenSolaris was developed as a combination of several software consolidations that were open-sourced subsequent to Solaris 10, and was meant to be the community-driven effort to provide the future code-base of Solaris 10 onwards..
Unix (officially trademarked as UNIX, sometimes also written as Unix with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna. Today's Unix systems are split into various branches, developed over time by AT&T as well as various commercial vendors and non-profit organizations. As of 2007, the owner of the trademark is The Open Group, an industry standards consortium. Only systems fully compliant with and certified to the Single UNIX Specification are qualified to use the trademark; others are called "Unix system-like" or "Unix-like". During the late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix (particularly of the BSD variant, originating from the University of California, Berkeley) by commercial startups, the most notable of which are Solaris, HP-UX, and AIX. Today, in addition to certified Unix systems, Unix-like operating systems such as Linux and BSD are commonly encountered. Sometimes, "traditional Unix" may be used to describe a Unix or an operating system that has the characteristics of either Version 7 Unix or UNIX System V. Contents
What is stored in a files inode on a Linux or unix system?
In native filesystems, the inode stores:
- the owner (userid and groupid)
- file type
- access permissions
- file access times (datetime file modified, accessed; datetime inode modified)
- number of links to the file
- table of disk addresses for the blocks used by the data of the file
- file size
Directories are special files which contains a mapping linking names to an inode.
In many filesystems, short data can be stored in the directory.
Is a Unix a real operating system?
No. This is a common misconception. The source code to Unix operating systems has traditionally been licensed to vendors, but the code was never made available to most users. Some of the code from Unix systems prior to System III was released under a BSD license in 2002, but most System III and later code is still proprietary.
What is the difference between command and utility in UNIX?
A command is something that's built-in to the kernel, where as the utility is something that runs on top of the kernel. Example of utilities are: fdisk, copy, edit, etc.
Number of characters in a UNIX file name?
It depends on the version of the operating system and how it is configured. You would need to look at the MAX_PATH setting to determine what the exact maximum is for a path name.
In general, you should be able to get at least 255 characters and possibly much more depending on the system.
What is the significance of Unix?
Importance Of Unix
-support multiuser and multitasking.
-adaptability and simplicity.
-flexible file system.
-excellent network environment.
-portable.
- provide better security.
What is the purpose of a shell script?
A shell script is used to automatically enter a series of commands without having to make the user type them out.
What functions does Linux and or Unix provide in today business world?
A majority of servers, including most of the Internet, run on Linux or other Unix-like operating systems. As a desktop platform, it is used in Mac OS X, and some (particularly Linux distributions) are mainly used by more technically savvy users or hobbyists. The wide range of distributions (or "distros") means that there is a flavor for everyone. Additionally, the Linux kernel is used in the Android mobile phone operating system.
What is the difference between Solaris 9 and Solaris 10?
soalris 9 support:
* it only support terabyes
* only init phase no SMF services
* no zones concepts
solaris 10 support
* supports petabytes and zfs(zeta filesystems
* uses svcs services and SMF
* supports zones
more than ,
grub bootloader for x86 sytem, and NFSv4 is introduced.
differance between solaris 9 and sol 10
1. SMF - service management facilty
2. Zone
3. ZFS - Zeta Byte file system
4. Nfs 4.0 version
5. Multi terabyte file system (up to 16 TB ) in sol 9 1 TB only
6. Passwd authentication Sol 9 - 16 characters
sol 10 - 256 characters
What are the advantages of a Unix file system?
It is a system software and all the processes in the operating system can be controlled by the user.
Where can someone go to learn more about shell script?
Linux shell scripting tutorials are available as pdf files or videos where a lecturer speaks over a video of a computer console. This is where you can watch someone code in the bash environment and follow along.
There are many ways to do this, but the fastest and easiest is to use the 'uptime' command, which will tell you in a summary line how many users are logged in.
What is the command echo in unix mean?
it is a command in unix and unix like operating systems that places a string on the computer terminal.It is typically used in shell scripts and bath files screen or a file.
Why do you use shell commands?
Once upon a time, all computers were controlled by typing instructions. There was no GUI 'Graphic User Interface' as on modern computers. Whilst there is nothing wrong in using GUI entirely, some users would rather use the CLI 'Command Line Interface' on a terminal, either entirely or partly. Provided the user knows the code to type, it is often faster using CLI than the mouse and GUI.
input="yes"
while [[ $input = "yes" ]]
do
echo "------------"
echo "Calculator"
echo "------------"
PS3="Press 1 for Addition, 2 for subtraction, 3 for multiplication and 4 for division: "
select math in Addition Subtraction Multiplication Division
do
case "$math" in
Addition)
echo "Enter first no:"
read num1
echo "Enter second no:"
read num2
result=<code>expr $num1 + $num2</code>
echo Answer: $result
break
;;
Subtraction)
echo "Enter first no:"
read num1
echo "Enter second no:"
read num2
result=<code>expr $num1 - $num2</code>
echo Answer: $result
break
;;
Multiplication)
echo "Enter first no:"
read num1
echo "Enter second no:"
read num2
result=<code>expr $num1 \* $num2</code>
echo Answer: $result
break
;;
Division)
echo "Enter first no:"
read num1
echo "Enter second no:"
read num2
result=$(expr "scale=2; $num1/$num2" | bc)
echo Answer = $result
break
;;
*)
echo Choose 1 to 4 only!!!!
break
;;
esac
done
echo "Do you want to calculate again(yes/no):"
read input
echo "Thank you for using this program"
done
Does UNIX have a command line interface?
Several different versions of UNIX have GUI's or Graphical User Interfaces.
The most common example of UNIX with an interface is Mac OS X.
