how to get a list of child processes?

Thinking · 01-19-2006, 05:35 AM

hiho@ll

how do i obtain a list of child processes, which is very actual?
the problem i have: i need some statistics of my childs
this statistics are shared through shared memory
the problem: if a child dies, i don't know how "actual" my statistic is

i thought about using signals
but which signals should be caught by a child to know that it will die?
is segfault the only one?
or is it possible to receive a signal from a child by the parent so the parent knows child with pid pid dies?

thx@ll

Thinking · 01-19-2006, 07:37 AM

ok i think i found it:

if a child dies it sends SIGCHILD signal to the parent

parent:

Code:

signal(SIGCHILD,mysigchildfunc);

static void mysigchildfunc(){
 int status=0;
 pid_t pid = waitpid(-1,&status,WNOHANG);
 if(pid>0){
  // do some stuff so parent knows a child died (e.g. cleanup of shared memory,....)
 }
}

graemef · 01-19-2006, 07:42 AM

You want the SIGCHLD. This signal is sent whenever a child process stops. This is to allow the parent to do any necessary processing. If you don't handle it then you will end up getting zombie processes. Typically it is processed in a waitpid() For an example on how to code this got to:

Advanced Unix Programming Examples

graeme.