Path: utzoo!utgpu!water!watmath!clyde!rutgers!sri-spam!ames!hc!beta!unm-la!unmvax!nmtsun!hydrovax From: hydrovax@nmtsun.nmt.edu (M. Warner Losh) Newsgroups: comp.os.misc Subject: Re: OS features Summary: A brief explination and a pointer Message-ID: <1169@nmtsun.nmt.edu> Date: 14 Dec 87 19:55:22 GMT References: <1971@cup.portal.com> Organization: NMT Hydrology program Lines: 55 In article <1971@cup.portal.com>, Mark_G_Woodruff@cup.portal.com writes: [[ Mark is summarizing responces that he got and asks for some elaberation.]] > > Command completion (The DEC OS's get this better than Unix) > [Could you please elaborate?] > > Tops-20: the COMND jsys -- completion and help in every command. > [Please explain.] Command completion: This is a simple concept. When the user has typed in enough of the command to make it unique and hits a specified key (usually ESCAPE in TOPS-20), the rest of the command appears "by magic". This may be difficult to understand from a unix point of view, since all of the commands are cryptic beyond believe (they can be learned, but it is painful). In contrast the TOPS-20 and VMS commands are long and verbose, allowing you to know EXACTLY (or nearly so) what is going down. For example, on TOPS-20, to print a file you type @ PRint (file) Foo.txt /Copies:2 Where the uppercase letters denote what the user typed, then hit esacpe to complete rest of the command. The stuff in parens are noice words that allow the user a quick mneumonic reference. These words aren't stictly needed. I'm not exacltly sure about the number of letters in this command, but they are close. Now, you say, this is really stupid that I need to type an escape key many times for each command. You don't have to, as the EXEC on TOPS-20 will alos accept: @ PR FOO.TXT/C:2 @ PRIN FOO.TXT/COP:2 etc. You needn't use the command completion, but it was there if you got stuck. Very useful for learning the system. > > Most important feature: coherent design An obvious plug for VMS...... :-) > > VMS/AmigaDOS symbolic names. > [Please explain.] Symbolic name, also called logical names are in a way similar to environmental variables in UNIX. They differ in that they can be used as file names (that is the OPERATING SYSTEM understands them as such) in any contect where a file name would occure. They have the advantage that you can write code like: fopen ("SPOOL_DIR:tmp", "w"); and have SPOOL_DIR point to something useful. This means that you need not recompile your program to move the spooler directory. You can also change this, in certain cased, WHILE THE PROGRAM is running. From what I have seen, it appears that the symbolic names (which I read as logical names. Somebody correct me if I'm wrong) to be a superset of enviornment symbols. Warner Losh ...!lanl!unm-la!unmvax!warner%hydrovax -- bitnet: lush@nmt.csnet M. Warner Losh csnet: warner%hydrovax@nmtsun uucp: ...{cmcl2, ihnp4}!lanl!unmvax!nmtsun!warner%hydrovax ...{cmcl2, ihnp4}!lanl!unmvax!nmtsun!hydrovax Warning: Hydrovax is both a machine, and an account, so be careful.