Path: utzoo!utgpu!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!NUSVM.BITNET!GBOPOLY1
From: GBOPOLY1@NUSVM.BITNET (fclim)
Newsgroups: comp.sys.apollo
Subject: Re: fifo files on Apollo-systems.
Message-ID: <8906120441.AA13421@umix.cc.umich.edu>
Date: 12 Jun 89 04:38:14 GMT
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Organization: The Internet
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X-Unparsable-Date: Mon, 12 Jun 89 12:12:42 SST

Hi,
     In article <1176@draken.nada.kth.se> larss%draken%kth%mcvax.uucp@uunet.uu.
net (Lars Schylberg) writes

>I have a problem how to create fifo files on the Apollo
>system.  We are currently running BSD4.2 and 9.7.1.
>
>To get this to work we are supposed to create two devices with the
>command:
>
>mknod -p /dev/fifo.a
>mknod -p /dev/fifo.b
>
>This command is however not availble in 9.7.  I looked in the standard

FIFOs are System V goodies and not BSD-ism.   Mknod(8) is available under
SR9.7 -- look for it in /sys5/etc where /sys5 is the root for all SysV
stuff.  The command is
      mknod /dev/fifo.a p
-- the file (/dev/fifo.a) created will be a FIFO because of the p option.

>This command is however not availble in 9.7.  I looked in the standard
>library and found the mknod(2).  I wrote this program:
>
>main()
>{
>   int mode;
>   mode = 0010000;
>   mknod("/dev/fifo.a",mode);
>   mknod("/dev/fifo.b",mode);
>}
>
>and after that chmod 7777 fifo.a and fifo.b to be able to open those
>from our program.  That didn't work however.  What have I done wrong.

I do not have my man pages with me; so I can't really tell you.  In
       chmod 7777 /dev/fifo.a
the most significant 7 is the sticky bit (setuid, etc) and does not make
/dev/fifo.a a FIFO.
The one in mode = 0010000 may be the password to make /dev/fifo.a a FIFO;
you have to check the man pages (chmod(2) or is it stat(2)) on this -- look
up the System V version rather than the BSD4.2 version.

>I've seen there is a command mknod(8) with the syntax:
>
>/etc/mknod name [b] / [c] major minor
>
>I suppose that I want to create a character device with c
>but what do I set major and minor to.  The system source file

See "The Design of the Unix operating system" (Prentice Hall ISBN-0-87692-516-6
) by Maurice
Bach (chapter on I/O) for an explaination of major/minor -- he explained it
better than I ever could.

Hope this has been of help.

fclim          --- gbopoly1 % nusvm.bitnet @ cunyvm.cuny.edu
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singapore polytechnic
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