C Shell RPC help

Applications Programming
1

Hello everyone,

I am writing a rpc program, I have put the server program on a directory in another computer and i run the client program from my computer. I want that when i call a function in the server program it will have to execute a shell script and the retruning of the shell script be caught by the server program and sent back to my client to watch or manipulate.

2

And your question is? Do you need help with C? Sockets? Calling other programs? Capturing their output?
By the way, what's your program supposed to do that SSH can't?

3

i want to capture the output of a shell program from my C program calling it. Any ideas? I have used popen till now. Is there any other way, because i don't want the output from the shell to be echoed to the servers terminal.

4

Where does it echo anything to the shell??

$ cat process.c
#include <stdio.h>
#include <unistd.h>

int main(int argc, char **argv)
{
    FILE *proc, *out;
    char buffer[1024];

    proc = popen("/bin/ls /", "r");
    out = fopen("output.txt", "w");

    while (!feof(proc)) {
        fgets(buffer, 1024, proc);
        fprintf(out, "%s", buffer);
    }
    fclose(out);
    pclose(proc);

    return 0;
}
$ ./process
$ cat output.txt
bin
boot
dev
etc
home
lib
lost+found
media
mnt
opt
proc
root
sbin
srv
sys
tmp
usr
var
var

I still fail to understand what you're trying to accomplish, could you clarify that a bit more?

5

here is the layout of my files:

On the server PC:
server_program
shell_scrip

On the client PC:
client_program

shell_script

ls -l /

What happens is that i call with popen the ./shell_script the values are echoed to the servers terminal.

shell = popen("./shell_script", "r")

//and then comes the reading
6

Then you've either got one weird terminal setup (unless I'm mistaken, in which case I'm asking for enlightenment), or your shell script (or a program within) explicitly writes to the terminal, or your program still has some debug printf()'s in it writing to a term.

I couldn't reproduce your problem even with fork()ing and closing all (unneeded) file descriptors (code in attachment)

$ ./process
$ cat output.txt
bin
boot
dev
etc
home
lib
lost+found
media
mnt
opt
proc
root
sbin
srv
sys
tmp
usr
var
var
insgesamt 0
lr-x------ 1 pludi users 64 30. Apr 13:12 0 -> pipe:[1498244]
l-wx------ 1 pludi users 64 30. Apr 13:12 1 -> /tmp/testbed/output.txt
l-wx------ 1 pludi users 64 30. Apr 13:12 1 -> /tmp/testbed/output.txt
7

No i call ls from my terminal so it is normal that it will print something. Thanx very much for the help.