c program that executes during a certain amount of time

jagman · 04-12-2005, 10:01 AM

Good day to all of you.
How I make a C program to executes for a certain amount of time?
For example:
My C program capture some data from the output of tcpdump. But I want that this program capture only the first 10 minutes of data from the output of tcpdump. How can i do that?

itsme86 · 04-12-2005, 10:04 AM

Check out the man page for the alarm() function. You could set the timer to go off in 600 seconds. Make a signal handler for SIGALRM that simply exits the program.

jagman · 04-12-2005, 06:50 PM

Good day to all of you.
I`m doing a C program that creates and exec another process( with fork and exec). Now I want that the child process executes a a system command (shell function) but that shell command ( tcpdump) finish only when the CTRL+c is enter.
How can I make this child process to stop exec? How can I send interuption signals to the child process?

itsme86 · 04-13-2005, 12:37 AM

fork() returns the child's PID to the parent. Store it somewhere and then send a signal to it using kill().

jagman · 04-13-2005, 08:33 AM

I tried to get the pid of the chil process but i get the number PID= 0 , and when i used that in the kill option the kill option interrupt all the process.

perfect_circle · 04-13-2005, 08:44 AM

Quote:

Originally posted by jagman
I tried to get the pid of the chil process but i get the number PID= 0 , and when i used that in the kill option the kill option interrupt all the process.

When you use fork() the program will be duplicated and a child process will be created that is exactly the same as the father. The only difference is the return value of fork. The pid of the child will be returned to the father and 0 will be returned to the child. SO only the child will get 0.

Use an "if" to distinguish the father from the child.

Code:

if ( PID=fork() )
{
   /*I'm the father*/
.......................................
......................................
..................................
}
/*the child continues from here*/

itsme86 · 04-13-2005, 09:22 AM

You missed a key part of my reply:

Quote:

fork() returns the child's PID to the parent.

You appear to be capturing the child's PID from the child process.