Free Essays on Unix

UNIX has served many different government and scientific entities in the past and continues to be enhanced by software designers in order to better serve customers by being responsive to today’s marketplace. It is obvious that with public demand for internet services, combined with the fact that the internet is UNIX-based, there is no immediate threat to the UNIX operating system. The unique advantage of the UNIX operating system when it was introduced was that it could (and still does) run on dissimilar machines, unheard of prior to 1969. UNIX also can run more than one program at a time, store complex graphics and databases, and link to other UNIX and mainframe computer systems, including DOS since the late 1980s. UNIX-based systems control various programs written by many companies to distribute information between multiple computers within the network. UNIX at first worked over ARPnet the ARPA network grew throughout the 1970s when computer networks from various organiz ations, both nationally and internationally, began to link to ARPAnet, mostly for transferring engineering and scientific research data. The ARPAnet eventually migrated into what we know as the World Wide Web. The Web allows users to easily browse through hypertext and multimedia located on various computers and mainframe systems around the world. Prior to the CERN project, Internet users had to know UNIX programming language and move around in a cumbersome UNIX shell environment. The Web can best be described as a â€Å"global interactive, dynamic, cross-platform, distributed, graphical hypertext information system that operates over the Internet. It operates on many protocols, including FTP, Gopher, UseNet, WAIS databases, and TELNET. Most of the text transferred over the Internet is written in hypertext markup language (HTML). Graphics are transferred via standard generalized markup language (SGML) through the UNIX operating system. No one owns the web, but a... Free Essays on UNIX Free Essays on UNIX UNIX has served many different government and scientific entities in the past and continues to be enhanced by software designers in order to better serve customers by being responsive to today’s marketplace. It is obvious that with public demand for internet services, combined with the fact that the internet is UNIX-based, there is no immediate threat to the UNIX operating system. The unique advantage of the UNIX operating system when it was introduced was that it could (and still does) run on dissimilar machines, unheard of prior to 1969. UNIX also can run more than one program at a time, store complex graphics and databases, and link to other UNIX and mainframe computer systems, including DOS since the late 1980s. UNIX-based systems control various programs written by many companies to distribute information between multiple computers within the network. UNIX at first worked over ARPnet the ARPA network grew throughout the 1970s when computer networks from various organiz ations, both nationally and internationally, began to link to ARPAnet, mostly for transferring engineering and scientific research data. The ARPAnet eventually migrated into what we know as the World Wide Web. The Web allows users to easily browse through hypertext and multimedia located on various computers and mainframe systems around the world. Prior to the CERN project, Internet users had to know UNIX programming language and move around in a cumbersome UNIX shell environment. The Web can best be described as a â€Å"global interactive, dynamic, cross-platform, distributed, graphical hypertext information system that operates over the Internet. It operates on many protocols, including FTP, Gopher, UseNet, WAIS databases, and TELNET. Most of the text transferred over the Internet is written in hypertext markup language (HTML). Graphics are transferred via standard generalized markup language (SGML) through the UNIX operating system. No one owns the web, but a... Free Essays on Unix Following is all the information that you need to understand the workings of the UNIX operating system (Berkley 4.2). Patched together by The War On the security side of UNIX: - On the Security of UNIX Dennis M. Ritchie Recently there has been much interest in the security aspects of operating systems and software. At issue is the ability to prevent undesired disclosure of information, destruction of information, and harm to the functioning of the system. This paper discusses the degree of security which can be provided under the system and offers a number of hints on how to improve security. The first fact to face is that was not developed with security, in any realistic sense, in mind; this fact alone guarantees a vast number of holes. (Actually the same statement can be made with respect to most systems.) The area of security in which is theoretically weakest is in protecting against crashing or at least crippling the operation of the system. The problem here is not mainly in uncritical acceptance of bad parameters to system calls there may be bugs in this area, but none are known- but rather in lack of checks for excessive consumption of resources. Most notably, there is no limit on the amount of disk storage used, either in total space allocated or in the number of files or directories. Here is a particularly ghastly shell sequence guaranteed to stop the system: while :; do mkdir x cd x done Ether a panic will occur because all the i-nodes on the device are used up, or all the disk blocks will be consumed, thus preventing anyone from writing files on the device. In this version of the system, users are prevented from creating more than a set number of processes simultaneously, so unless users are in collusion it is unlikely that any one can stop the system altogether. However, creation of 20 or so CPU or disk-bound jobs l...