 ans  =
 
    2.  
 
-->exec('Example12.sci')
 
-->clear
 
-->flag=1
 flag  =
 
    1.  
 
-->mode(-1)
Current date is 23-Jun-2013 
 
Welcome to the Textbook Companionship Project 2013 
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 Book Title                             :       UNIX CONCEPTS AND APPLICATIONS    
 
 Book Edition                         :                                                                           4   
 
 Book Author                          :                                                    Sumitabha Das   
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 Code Author                          :                                                     Pranav Bhat T   
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 Chapter Number                    :                                                                            24   
 
 Chapter Title                         :                              Systems programming II- Files   
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Example 12    :    Show the effect of sharing a pipe between two processes from parent to child 
 
 ****************************************************************   
 
 Answer    :      
 
 INSTRUCTIONS   :    
  
 1.These programs are part of systems programming PURELY in Unix and the commands have NO EQUIVALENT IN SCILAB   
  
 2.However the .c files which are displayed here are also made into a seperate file.If you are a unix user then try compiling and 
       running the programme with gcc or cc compiler                                                                              
  
 3.The outputs displayed here are just MOCK OUTPUTS which are DISPLAYED IN THE TEXTBOOK   
  
 4.The inconvenience is regretted.   
.............Press [ENTER] to continue.....	UNIX SHELL SIMULATOR(DEMO VERSION WITH PRELOADED COMMANDS)




$ cat pipe.c      # to open the file emp.lst /* Program: pipe.c -- Shares a pipe between two processes for data to flow from parent to child*/
#include <stdio.h>
#include <unistd.h>

void quit(char *, int);
int main(void) {
    int n,fd[2];       /* fd[2] to be filled up by pipe() */
    char buf[100];     /* Buffer to be used by read() */
    
    if (pipe(fd) < 0)  /* fd[0] is read end */
    quit("pipe",1);    /* fd[1] is write end */
   
    switch (fork()) {    /* Pipe has four descriptors now */
    case -1:quit("Fork error",2);
     case 0:close(fd[1]); /* CHILD-Close write end of pipe */
            n=read(fd[0],buf,100);  /* and read from its read end */
            write(STDOUT_FILENO,buf,n);
            break;
     default: close(fd[0]);  /*PARENT-Close read end of pipe */
            write(fd[1],"Writing to pipe\n", 16); /* write to write end */
     }
     exit(0);
}
 $ cc shell.c $ a.out  Writing to pipe 


$ exit        #To exit the current simulation terminal and return to Scilab console

........# (hit [ENTER] for result)

			BACK TO SCILAB CONSOLE...
Loading initial environment 
-->diary(0)
