UNIX for Advanced & Expert Users

I am trying to figure out why when i have the following code

int main( { printf("0\n"); fork(); printf("1\n"); exit(0);}

and type in the shell

a.out | cat

the output of this program is
0
1
0
1

instead of
0
1
1

does anyone know?

What OS are you using? I tried this on Solaris 8, and its working fine.(0 1 1).

Blowtorch, try piping it to 'cat' or echo $(a.out).

I get the same results.

Code:

$ a.out
0
1
1
$ echo $(a.out)
0 1 0 1
$ a.out | cat
0
1
0
1
$

It stumped me for awhile, but I believe I know why this is happening. The fork() call is copying everything in memory to a child process, including the output buffer. Since the output buffer wasn't flushed before the fork, there was a '0' character in the buffer, and that was also copied. Try flushing the buffer before the fork(). It worked for me.

Code:

int main () { printf("0\n"); fflush(stdout);  fork(); printf("1\n"); exit(0);}

Nathan

Thanks that seems to make perfect sense