LinuxQuestions.org - [SOLVED] redirecting output, observe with tail -f <file>, while running, without screen?

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redirecting output, observe with tail -f <file>, while running, without screen?

Hello All,

I know how to redirect output from one program to a file, for example, when I do:
ping linuxquestions.org > log &
I can observe the contents in real-time, while the program is running with:
tail -f log

But if I create my own little program, like for example:

Code:

#include <stdio.h>

#include <signal.h>



unsigned char stop = 0;



void catch_signal(int sig) {

    printf("Signal SIGINT or SIGTERM catched: %d, exiting...\n", sig);

    stop = 1;

}



int main(void) {



    (void) signal(SIGINT, catch_signal);

    (void) signal(SIGTERM, catch_signal);



    int i = 0;

    while (! stop) {

        sleep(1);

        fprintf(stdout, "hello %d\n", i);

        i++;

    }

}

Then with ./a.out > log &, the output is redirected, but the output is only written to log, after the program is stopped, why?

Why does it work for ping and not for my own simple C program (compile with gcc without any other options)? How I can I do the same with my program without using a program like screen.

Thanks the for help,

srons

BTW, the '&' is redundant. Re-direction works anyway eg

./myprog >myprog.out 2>myprog.err

OR

./myprog >myprog.log 2>&1

The '&' you used at the end simply puts the prog in the background, which is a separate issue.

It works, thanks! :)