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From: cedman@lynx.ps.uci.edu (Carl Edman)
Newsgroups: comp.unix.programmer
Subject: Re: how to put a program into .plan file
Message-ID: <CEDMAN.90Sep26182933@lynx.ps.uci.edu>
Date: 27 Sep 90 01:29:36 GMT
References: <1990Sep26.155456.1656@agate.berkeley.edu>
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In-reply-to: labb-4ac@web-4b.berkeley.edu's message of 26 Sep 90 15:54:56 GMT

In article <1990Sep26.155456.1656@agate.berkeley.edu> labb-4ac@web-4b.berkeley.edu (superMan (the web dweller)) writes:
   Pardon my ignorance, but how can you write a C program which checks the
   status of the file to see whether someone has opened it?  Exactly what
   system call or library function do you use?

   Please send reply to Internet address achoi@cory.berkeley.edu.
   Thank you so much for your reply.

   Name:  Andrew Choi
   Internet Address:  achoi@cory.berkeley.edu
   #include <std/disclaimer.h>

Here is the most simple possible solution. Something I tried a few
days ago. Run the output and try "cat tfifo". You will get 3 different
results then the run-ed program will terminate.

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

main()
   {
   int fd;
   unlink("tfifo");
   mkfifo("tfifo",S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH);
   fd=open("tfifo",O_WRONLY);
   write(fd,"test1\n",7);
   close(fd);
   sleep(1);
   fd=open("tfifo",O_WRONLY);
   write(fd,"test2\n",7);
   close(fd);
   sleep(1);
   fd=open("tfifo",O_WRONLY);
   write(fd,"test3\n",7);
   close(fd);
   sleep(1);
   unlink("tfifo");
   }

I hope looking at this code will answer your question (Maybe your system
hasn't got mkfifo, use mknod then).













Theorectial Physicist,N.:A physicist whose   | Send mail
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