HI,
I have to implement a program using exec command to illustrate
concurrent and sequential process. What I did is just create two input
file

Alpha.txt
========
abcdefghijklmnopqrstuvwxyz
abcdefghijklmnopqrstuvwxyz
abcdefghijklmnopqrstuvwxyz
abcdefghijklmnopqrstuvwxyz
abcdefghijklmnopqrstuvwxyz
.  .  .
abcdefghijklmnopqrstuvwxyz (upto 50 lines)

Number.txt
========
1234567890
1234567890
1234567890
. .  .
1234567890 ( upto 50 lines)

my code is
========
#include <sys/types.h>
#include<unistd.h>
#include<iostream>

using namespace std;

int pid1,pid2;

int main ()
{

pid1 = fork();  //first child process

if (pid1<0){

perror("error");

}

if (pid1 ==0)
{

execl("/bin/cat","cat","Alpha.txt",NULL);

}
//parent process

if (pid1>0) {

}

pid2 =fork();       //second child process

if (pid2==0){

execl("/bin/cat", "cat","Number.txt",NULL);
}

if (pid2>0){

}
}

output ( I want output in this manner)
===========================
For Concurrent process:-

abcdefghijklmnopqrstuvwxyz
1234567890
abcdefghijklmnopqrstuvwxyz
1234567890
abcdefghijklmnopqrstuvwxyz
abcdefghijklmnopqrstuvwxyz
1234567890
.................... ( this its goes one)

but i am getting all the alphabets first then number( they are not
overlapping which it should happened  in concurrent)

For Sequential process :

I want all alphabets then number

please help me, Thanks in advance

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Bhavin <v2desperado@gmail.com> writes:

> HI,
>      I have to implement a program using exec command to illustrate
> concurrent and sequential process. What I did is just create two input
> file
>
> Alpha.txt
> ========
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
>           .  .  .
> abcdefghijklmnopqrstuvwxyz (upto 50 lines)
>
> Number.txt
> ========
> 1234567890
> 1234567890
> 1234567890
>      . .  .
> 1234567890 ( upto 50 lines)
>
> my code is
> ========
> #include <sys/types.h>
> #include<unistd.h>
> #include<iostream>
<snip program that forks and runs two copies of "cat">
> output ( I want output in this manner)
> ===========================
> For Concurrent process:-
>
> abcdefghijklmnopqrstuvwxyz
> 1234567890
> abcdefghijklmnopqrstuvwxyz
> 1234567890
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
> 1234567890
>  ..................... ( this its goes one)
>
> but i am getting all the alphabets first then number( they are not
> overlapping which it should happened  in concurrent)

Ah, but that is allowed.  Concurrent does not mean "as interleaved as
I want but no more" but simply that both run eventually.

Try using a longer-running program and see what happens.  The command
"yes" can be useful here, but you should be ready to kill the
child processes by hand since "yes" never stops.

--
Ben.

[ Post a follow-up to this message ]

On Sep 25, 2:57 pm, Bhavin <v2desper...@gmail.com> wrote:
> HI,
>      I have to implement a program using exec command to illustrate
> concurrent and sequential process. What I did is just create two input
> file
>
> Alpha.txt
> ========
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
>           .  .  .
> abcdefghijklmnopqrstuvwxyz (upto 50 lines)
>
> Number.txt
> ========
> 1234567890
> 1234567890
> 1234567890
>      . .  .
> 1234567890 ( upto 50 lines)
>
> my code is
> ========
> #include <sys/types.h>
> #include<unistd.h>
> #include<iostream>
>
> using namespace std;
>
> int pid1,pid2;
>
> int main ()
> {
>
>         pid1 = fork();  //first child process
>
> if (pid1<0){
>
>         perror("error");
>
> }
>
> if (pid1 ==0)
>         {
>
>              execl("/bin/cat","cat","Alpha.txt",NULL);
>
>         }
> //parent process
>
> if (pid1>0) {
>
>         }
>
> pid2 =fork();       //second child process
>
> if (pid2==0){
>
>          execl("/bin/cat", "cat","Number.txt",NULL);
>         }
>
> if (pid2>0){
>
> }
> }
>
> output ( I want output in this manner)
> ===========================
> For Concurrent process:-
>
> abcdefghijklmnopqrstuvwxyz
> 1234567890
> abcdefghijklmnopqrstuvwxyz
> 1234567890
> abcdefghijklmnopqrstuvwxyz
> abcdefghijklmnopqrstuvwxyz
> 1234567890
>  ..................... ( this its goes one)
>
> but i am getting all the alphabets first then number( they are not
> overlapping which it should happened  in concurrent)

That would only happen if your system were very slow.  Most likely it
is fast enough that 'cat Alpha.txt' completes in its first timeslice,
before one is given to the other process.

If you make Alpha.txt and Number.txt really large, you will probably
see them interlaced (say 10000 lines of Alpha then 10000 lines of
Number).

If it were important that they alternate lines, you'd have to use your
own program instead of cat, which would write a line and then
communicate with the other process to agree on who should go next.

> For Sequential process :
>
> I want all alphabets then number

man waitpid

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