April 15, 2013
File Management Paper – Unix® File Permissions
The name Unix® refers to a play on words rather than being an acronym. During the mid-1960 an operating system was developed at MIT that allowed multiple users to work on a system at any one time. It was called Multiplexed Information and Computing System (MULTICS). In the late 1960s, closer to 1970, a couple programmers at Bell Laboratories wrote an assembler to interface with a DEC PDP-7. Unlike MULTICS, this version allowed only one user to access it at a time. One of the programmers kiddingly called it Uniplexed Information and Computing System (UNICS) pronounced Unix. In the spring of 1971, the interest in Unix® grew and Bell Laboratories began to dedicate work to developing Unix®. Since Bell Laboratories was considered a monopoly by the government, they could not provide the OS for a fee; therefore it was distributed for free (Stewart, 2011). Today there is a mix of free and pay for use versions of Unix®. There is another flavor called Linux, which at its very core is similar to Unix® and is more widely used in the programming populace as a whole. The focus of this paper is to illustrate how files are shared amongst a user based of 5000 in Unix®. 4990 of the users will have read/write capabilities while the other 10 are denied access. The Unix® file system is laid out in a hierarchal manner with specific permissions given at each level. For files that a user creates, the system and that user are the only ones with permissions to modify or delete the file. The same is true for folders, but additional settings are required so that all the files within the folder carry the same permissions. Unix®, as well as all modern operating systems, uses Access Control Lists (ALCs) to control who has what permissions to files and folders. The first step in granting file permission to the 4990 users, a group...