On behalf of David Winkler --Review: The UNIX Time-Sharing system

From: Gang Zhao (galaxy_at_cs.washington.edu)
Date: Sun Jan 11 2004 - 23:11:05 PST

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    The article discusses UNIX at a time when it only had 40 installations.

    Unix was remarkable as an interactive system, but with batch fascility. Unix was at the time used for research and for document preparation. While the operating system itself was fairly simple it had a wide variety of small utilities available. It's come a long way since then.

    While the operating system was originally written in assembly language, it was re-written in C. The authors describe the benefits of this rewrite as including ease of understanding and modification. It seems like this might have been new.

    The file system's definition of linking is the one criticized in the Multics document.

    Unix implements I/O largely through special files. This is actually a pretty elegant solution.

    Unix allowed for removable file systems, with the requirement that no link may exist between one file system hierarchy and another. All of the other papers that we have read only talk about fixed disks.

    A set-user-id bit exists, which if set impersonates the owner of the file during execution of the file. This is a pretty primitive version of impersonation.

    Files are limited in size to 1 Megabyte. Pointers to files are simply an integer.

    The shell is simply a program that creates new processes. Unix interestingly supports the ability to set a different shell if the user chooses. Interprocess communications are implemented as pipes, with communication being accomplished with the standard file I/O commands. The output of one process can also be used as the input of another process, also called a filter. Wow.

    Path searching is done, but this is not as complete a solution as has been eventually implemented.

    This article shows the beginning of the Unix era.


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