Linux

The key features of modern UNIX are: virtual memory, multitasking and multiuser.

The original design philosophy of UNIX was to distribute the functionality in small parts of programs. Thus, the user can obtain new functionality and new features in a relatively simple way, using different combinations of small parts (programs). Moreover, in the case of the emergence of new utilities (and indeed are) can be integrated into the workspace. Modern versions of the UNIX system are organized for easy use and functional network, so it is very common to find versions of the UNIX system on large mainframes supporting hundreds of users simultaneously. The internal communication tools of the system, routines easy acceptance of additional low-level device and the flexible organization of the file system are natural to the network environment today.

The UNIX system, with its ability to multitask and its huge base of software for communications, computing makes it simple to network, also allowing efficient sharing of devices such as printers and hard disk. The version of SVR4 (System V Release 4), is the latest version of the UNIX from AT & T. It has been ported to most mainframe machines and is the current standard for online AT & T. SVR4 has been significantly improved over previous versions. One such improvement is the graphical user interface (GUI) that allows the use of X Windows. Commercial systems SCO UnixWare and Solaris from Sun Microsystems are based on SVR4. The biggest improvement is the addition of SVR4 full support for local area networks. The management of networked machines has been improved greatly and remote administration is now possible through the network.Network Connection Support for local area networks in SVR4 is greatly improved compared to older versions of the UNIX operating system.

In addition to supporting low-level routines in the kernel, there is a simple and friendly software to connect the two LAN’s main available in the UNIX world, Ethernet and Starlan. UNIX is a multiuser operating system, not only can use more than one person at a time, but that different users receive different treatment. In order to identify people, UNIX performs a process called income (login). Each UNIX file has associated a set of permissions. These permissions tell the operating system who can read, write or execute as a program for file. UNIX recognizes three different types of individuals: first, the file owner, and second, the “group” and, finally, is the “rest” that are neither owners nor belong to the group called “other.” In general, UNIX machines are networked, meaning that the commands are not physically implemented on the computer on which you are typing, but on a computer that is connected. Sometimes you have to explicitly connect, giving a host name from a terminal emulator program, ie a program that allows a computer to act as a keyboard and screen of another computer remotely. There are many ways to communicate with other users connected to the same system, or who are users of it. To first order using the talk, which connects to a user when connected to the system.

Not only can you connect a user with the same system, but of anyone connected to it, for example, on the Internet. The most common way to send the email. This method allows you to send ASCII text, sometimes with attached files (attachments), these files must first be converted to ASCII, to be sent via this medium. UNIX has a command, mail, to send email, but not too friendly to the user and therefore use other programs like Pine, to send or receive mail. Connecting to other computers Since UNIX is a network operating system, many UNIX computers are connected to each other and the Internet. UNIX A computer usually offers a range of services to the network by continuously running programs called daemon. These daemon listening port or numeric address that identifies a service and act as servers. To use such services are used client programs, you already know which port it is and what is the proper protocol to talk to that daemon. Of course, to use these programs must first have permission to use such port or protocol, and then access the remote machine, ie you have to”authenticate”or identified as an authorized user of the machine. Some of these programs are telnet, rlogin, rsh, ftp, etc..

Summary of UNIX

UNIX is the most widely used in scientific research, but its application in other environments has been widely accepted.
The version of SVR4 (System V Release 4), is the latest version of the UNIX from AT & T.
The original design philosophy of UNIX was to distribute the functionality in small parts of programs.
In general, UNIX machines, the commands are not physically implemented on the computer on which you are typing, but that to which one is connected.
UNIX A computer usually offers a range of services to the network by continuously running programs called daemon.
Linux Linux is a clone of the UNIX operating system that runs on multiple platforms, especially on PCs with Intel 80386 processor or better. Linux can turn any PC into a workstation with the best qualities of UNIX. This system has been installed in both business and universities, as for personal use. What makes Linux so different is that it is a free implementation of UNIX. It was and still is developed by a group of volunteers, mainly from Internet, who exchange code, report tricks and solve problems in a fully open. There is a set of standardization documents published by the IEEE POSIX named. Linux first of all documents meet the POSIX POSIX-1 and-2. Linux has a cache or cache improves disk performance.

This means that RAM temporarily stores information pertaining to the permanent storage system. The differences between what Linux thinks is in the disk and what is actually stored in it, is synchronized every 30 seconds. In Linux you can run most popular software for UNIX, including the X Window System The X Window System, or simply X, is a standard graphical user interface for UNIX machines and is a powerful environment that supports many applications. Using the X Window System, you can have multiple terminal windows on the screen at once (virtual consoles), each having a different workout. With TCP / IP, a Linux machine running X applications can be deployed on other machines. At present, X is used in all available versions of UNIX. The Linux system is mostly compatible with several UNIX standards at the source level, including IEEE POSIX.1, UNIX System V and Berkeley UNIX System Distribution (BSD). All source code for Linux, including kernel or kernel, drivers, libraries, user programs and development tools are free. Linux provides a complete software implementation of TCP / IP and includes a complete programming environment that includes all the standard libraries, programming tools, compilers and debuggers that are expected from other UNIX systems.

There are a variety of commercial software available for Linux. In these times, you can purchase any type of application, such as Motif, which is an interface to the X Window system like Microsoft Windows, WordPerfect (the popular word processor) or Maple, which is a complex package that performs symbolic manipulations, for Linux. Linux supports virtual consoles (VC), which are a way to make a machine appear as multiple terminals, all connected to the same Linux kernel. Fortunately, using virtual consoles is one of the simpler things in Linux, because there are “hot keys” to quickly switch between consoles. Linux systems generally come with eight VC enabled by default. To establish communication networks, Linux supports two network protocols: TCP / IP and UUCP. With Linux, TCP / IP and Internet connection, users can communicate with other computers. Linux also supports connectivity to Microsoft Windows, Macintosh and LocalTalk AppleTalk and Novell IPX.

The TCP / IP (Transmission Control Protocol / Internet Protocol) is a standard Linux system and computers in the network need to use it. With TCP / IP, all information is converted into packets that are sent immediately to the destination address. This protocol allows you to run interactive applications over the network. TCP / IP is the solution for communication between LAN’s that do not properly satisfy low-cost protocol UUCP. UUCP (UNIX-to-UNIX Copy) is an old mechanism for file transfer, electronic mail and news between UNIX machines. Historically, UUCP machines are connected over telephone lines via modem, but UUCP can transfer data over a TCP / IP in the same way. Linux Summary 1. Linux is a clone of the UNIX operating system that runs on multiple platforms. 2. What makes it different is that Linux is a free implementation of UNIX. 3.In Linux you can run most popular software for UNIX, including the X Window System 4. Linux provides a complete software implementation of TCP / IP. 5. Linux supports virtual consoles (VC). Back to topics in this section Back to Home Page Access since December 3, 2000 Find more information on the Internet with this excellent search engine Search the Web. Any comments to: Mr. Manuel Espinoza Curiel me_techpage@yahoo.com Ciudad Obregon, Sonora, Mexico