Does Linux Kernel always send signal to parent process
Hi just two questions about sending/receiveing signal
Q1- does Linux Kernel always send signals to parent process?
Q2- lets say I use fork() twice to create child processes
int main()
fork();
fork();
printf("hellon");
exit(0);
after the first fork(), a child process(lets say it is called child_1, and the parent process is called parent_1) is created.
On the second fork(), child_1 create another child process (lets say it is called child_2).
so my understanding is, child_1 is actually a parent process in the context of child_2, so now lets say the shell runs the program and a user type ctrl-c at the keyboard,
so the kernel sends the SIGINT, but to which process, parent_1 or child_1 or both, since child_1 is also parent process of child_2?
c linux exception signals
asked Nov 16 '18 at 1:37
amjadamjad
49212
add a comment |
Hi just two questions about sending/receiveing signal
Q1- does Linux Kernel always send signals to parent process?
Q2- lets say I use fork() twice to create child processes
int main()
fork();
fork();
printf("hellon");
exit(0);
after the first fork(), a child process(lets say it is called child_1, and the parent process is called parent_1) is created.
On the second fork(), child_1 create another child process (lets say it is called child_2).
so my understanding is, child_1 is actually a parent process in the context of child_2, so now lets say the shell runs the program and a user type ctrl-c at the keyboard,
so the kernel sends the SIGINT, but to which process, parent_1 or child_1 or both, since child_1 is also parent process of child_2?
c linux exception signals
asked Nov 16 '18 at 1:37
amjadamjad
49212
Q1 is unclear. If you mean "when a process is signalled, does the kernel also always signal its parent", then the answer is No. If you mean something else, maybe you should explain.
– Jonathan Leffler
Nov 16 '18 at 1:44
After the first fork, you have a parent, P, and it has one child, C1. After the second fork, you have the parent P, and it has two children (C1, and C2), and C1 has a child process, G1. They all print and exit (why no newlines?). You might do better usingpause()thanexit(0); it gives you time to send a signal. If you type control-C at the keyboard exactly right (or you're usingpause()), then the signal will be sent to all processes in a process group — and all of P, C1, C2, and G1 would be interrupted (receive the interrupt signal).
– Jonathan Leffler
Nov 16 '18 at 1:48
1
You might want to read this: stackoverflow.com/questions/6108953/…
– mevets
Nov 16 '18 at 2:03
add a comment |
Hi just two questions about sending/receiveing signal
Q1- does Linux Kernel always send signals to parent process?
Q2- lets say I use fork() twice to create child processes
int main()
fork();
fork();
printf("hellon");
exit(0);
after the first fork(), a child process(lets say it is called child_1, and the parent process is called parent_1) is created.
On the second fork(), child_1 create another child process (lets say it is called child_2).
so my understanding is, child_1 is actually a parent process in the context of child_2, so now lets say the shell runs the program and a user type ctrl-c at the keyboard,
so the kernel sends the SIGINT, but to which process, parent_1 or child_1 or both, since child_1 is also parent process of child_2?
c linux exception signals
asked Nov 16 '18 at 1:37
amjadamjad
49212
Hi just two questions about sending/receiveing signal
Q1- does Linux Kernel always send signals to parent process?
Q2- lets say I use fork() twice to create child processes
int main()
fork();
fork();
printf("hellon");
exit(0);
after the first fork(), a child process(lets say it is called child_1, and the parent process is called parent_1) is created.
On the second fork(), child_1 create another child process (lets say it is called child_2).
so my understanding is, child_1 is actually a parent process in the context of child_2, so now lets say the shell runs the program and a user type ctrl-c at the keyboard,
so the kernel sends the SIGINT, but to which process, parent_1 or child_1 or both, since child_1 is also parent process of child_2?
c linux exception signals
c linux exception signals
asked Nov 16 '18 at 1:37
amjadamjad
49212
asked Nov 16 '18 at 1:37
amjadamjad
49212
asked Nov 16 '18 at 1:37
amjadamjad
49212
asked Nov 16 '18 at 1:37
amjadamjad
49212
asked Nov 16 '18 at 1:37
amjadamjad
49212
49212
Q1 is unclear. If you mean "when a process is signalled, does the kernel also always signal its parent", then the answer is No. If you mean something else, maybe you should explain.
– Jonathan Leffler
Nov 16 '18 at 1:44
After the first fork, you have a parent, P, and it has one child, C1. After the second fork, you have the parent P, and it has two children (C1, and C2), and C1 has a child process, G1. They all print and exit (why no newlines?). You might do better usingpause()thanexit(0); it gives you time to send a signal. If you type control-C at the keyboard exactly right (or you're usingpause()), then the signal will be sent to all processes in a process group — and all of P, C1, C2, and G1 would be interrupted (receive the interrupt signal).
– Jonathan Leffler
Nov 16 '18 at 1:48
1
You might want to read this: stackoverflow.com/questions/6108953/…
– mevets
Nov 16 '18 at 2:03
add a comment |
Q1 is unclear. If you mean "when a process is signalled, does the kernel also always signal its parent", then the answer is No. If you mean something else, maybe you should explain.
– Jonathan Leffler
Nov 16 '18 at 1:44
After the first fork, you have a parent, P, and it has one child, C1. After the second fork, you have the parent P, and it has two children (C1, and C2), and C1 has a child process, G1. They all print and exit (why no newlines?). You might do better usingpause()thanexit(0); it gives you time to send a signal. If you type control-C at the keyboard exactly right (or you're usingpause()), then the signal will be sent to all processes in a process group — and all of P, C1, C2, and G1 would be interrupted (receive the interrupt signal).
– Jonathan Leffler
Nov 16 '18 at 1:48
1
You might want to read this: stackoverflow.com/questions/6108953/…
– mevets
Nov 16 '18 at 2:03
Q1 is unclear. If you mean "when a process is signalled, does the kernel also always signal its parent", then the answer is No. If you mean something else, maybe you should explain.
– Jonathan Leffler
Nov 16 '18 at 1:44
Q1 is unclear. If you mean "when a process is signalled, does the kernel also always signal its parent", then the answer is No. If you mean something else, maybe you should explain.
– Jonathan Leffler
Nov 16 '18 at 1:44
After the first fork, you have a parent, P, and it has one child, C1. After the second fork, you have the parent P, and it has two children (C1, and C2), and C1 has a child process, G1. They all print and exit (why no newlines?). You might do better using
pause() than exit(0); it gives you time to send a signal. If you type control-C at the keyboard exactly right (or you're using pause()), then the signal will be sent to all processes in a process group — and all of P, C1, C2, and G1 would be interrupted (receive the interrupt signal).– Jonathan Leffler
Nov 16 '18 at 1:48
After the first fork, you have a parent, P, and it has one child, C1. After the second fork, you have the parent P, and it has two children (C1, and C2), and C1 has a child process, G1. They all print and exit (why no newlines?). You might do better using
pause() than exit(0); it gives you time to send a signal. If you type control-C at the keyboard exactly right (or you're using pause()), then the signal will be sent to all processes in a process group — and all of P, C1, C2, and G1 would be interrupted (receive the interrupt signal).– Jonathan Leffler
Nov 16 '18 at 1:48
1
1
You might want to read this: stackoverflow.com/questions/6108953/…
– mevets
Nov 16 '18 at 2:03
You might want to read this: stackoverflow.com/questions/6108953/…
– mevets
Nov 16 '18 at 2:03
add a comment |
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Q1 is unclear. If you mean "when a process is signalled, does the kernel also always signal its parent", then the answer is No. If you mean something else, maybe you should explain.
– Jonathan Leffler
Nov 16 '18 at 1:44
After the first fork, you have a parent, P, and it has one child, C1. After the second fork, you have the parent P, and it has two children (C1, and C2), and C1 has a child process, G1. They all print and exit (why no newlines?). You might do better using
pause()thanexit(0); it gives you time to send a signal. If you type control-C at the keyboard exactly right (or you're usingpause()), then the signal will be sent to all processes in a process group — and all of P, C1, C2, and G1 would be interrupted (receive the interrupt signal).– Jonathan Leffler
Nov 16 '18 at 1:48
1
You might want to read this: stackoverflow.com/questions/6108953/…
– mevets
Nov 16 '18 at 2:03