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ans =
1.
-->exec('Example13.sci')
-->clear
-->flag=1
flag =
1.
-->mode(-1)
Current date is 23-Jun-2013
Welcome to the Textbook Companionship Project 2013
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Book Title : UNIX CONCEPTS AND APPLICATIONS
Book Edition : 4
Book Author : Sumitabha Das
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code Author : Pranav Bhat T
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Chapter Number : 24
Chapter Title : Systems programming II- Files
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Example 13 : Show the method of running two programs in a pileline
****************************************************************
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 pipe2.c # to open the file emp.lst /* Program pipe2.c -- Runs two programs in a pipeline Child runs cat, parent runs tr */
#include <stdio.h>
#include <unistd.h>
void quit(char *message,int exit_status);
int main(void) {
int fd[2]; /* To be fille dup by pipe() */
if (pipe(fd) < 0) /* Now have four descriptors for pipe */
quit("pipe", 1);
switch (fork()) {
case -1: quit("fork", 2);
case 0: close(fd[0]); /* CHILD - Close read end first */
dup2(fd[1], STDOUT_FILENO); /* Connect stdout to write end */
close(fd[1]); /* and close original descriptor */
execlp("cat", "cat","/etc/hosts.equiv", (char *) 0);
default: close(fd[1]); /* PARENT -- Close write end first */
dup2(fd[0], STDIN_FILENO); /* Connect stdin to read end */
close(fd[0]); /* and close original descriptor */
execlp("tr", "tr", "'[a-z]'","'[A-Z]'",(char *) 0);
quit("tr", 4);
}
}
$ cc pipe2.c $ a.out SATURN
EARTH
MERCURY
JUPITER
$ 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)
|
