Confused about SIGHUP

[Sampath Kumar Herga]

Hi,

Not sure if this is the right forum for this question. Would appreciate
if someone could point me to the correct forum, if this isnt. 

I was trying the following program and the main thread also seems to
exit when the spawned thread exits. This happens only when I spawn the
program using the xterm -e <cmd> option to execute the program.

#include <pthread.h>
#include <signal.h>
#include <sys/types.h>
#include <linux/unistd.h>

_syscall0(pid_t,gettid)
pid_t gettid(void);


void* func(void* tmp1)
{
        printf("func; Process group = %d;\tpid =
%d;\ttid=%d;\tppid=%d\n",getpgrp(),getpid(),gettid(),getppid());
	sleep(2);
}

int main()
{
	pthread_attr_t attr;
	pthread_t thread;
	pthread_attr_init(&attr);

	pthread_create(&thread,&attr,func,0);

        printf("main; Process group = %d;\tpid =
%d;\ttid=%d;\tppid=%d\n",getpgrp(),getpid(),gettid(),getppid());
	while(1)
	{	
		printf("Hello World\n");
		sleep(1);
	}
}

main; Process group = 30100;    pid = 30100;    tid=30100;
ppid=30098
Hello World
func; Process group = 30100;    pid = 30100;    tid=30101;
ppid=30098
Hello World
Hello World


Looking at the strace, the main thread seems to be getting a SIGHUP.

30101 _exit(0)                          = ?
30100 <... rt_sigprocmask resumed> [], 8) = 0
30100 --- SIGHUP (Hangup) @ 0 (0) ---
30098 <... select resumed> )            = 1 (in [4], left {1, 0})
30098 --- SIGCHLD (Child exited) @ 0 (0) ---

I wasn't sure why SIGHUP is being delivered in this case when tid 30101
is not the process group leader?

Regards,
Sampath.
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