run c function in the background

schneidz · 09-06-2007, 02:55 PM

for example in bash:

Code:

(
while [ 1 ]
do
 echo hello-world
 sleep 1
done) &
cd p2501

will go to the project-2501 directory while echo-ing hello-world in the background.

how does one do something similar in c ?

Code:

while(1)
{
 printf("hello-world\n");
 usleep(1000000);
}     // background ?
chdir("p2501");

i figure some mixture of fork but i dont want it to overwrite the current process in memory.

am i not understanding how fork works ?

schneidz · 09-06-2007, 03:10 PM

why is there 2 of these ?

amways, i think i answered it here:
http://www.linuxquestions.org/questi...highlight=fork

i am out of practice so it isnt obvious to me how to make it work. but i will try:

Code:

int p;
p = fork();
if(p > 0)
{
 while(1)
 {
  printf("hello-world\n");
  usleep(1000000);
 }     // background ?
}
chdir("p2501");

schneidz · 09-06-2007, 03:19 PM

confirmed, works

lazyFoot_theMighty · 09-06-2007, 11:41 PM

If that is what you wan't, then go ahead. Using fork(), however, will create a new full process (Address space, stack, heap etc). It is often useful to just create multiple threads (control flows), within a single process. Taking this approach will allow shared memory access, as opposed to using pipes or sockets, and reduce memory overheads. Look at what is provided by the pthread library. I'm not a fan of the concurrency in posix, but pthread will provide everything you need. Saying this, fork() is fine for many applications as it has conceptual simplicity going for it.

bigearsbilly · 09-07-2007, 08:29 AM

or alternatively,

threads considered harmful

http://www.google.co.uk/search?hl=en...G=Search&meta=