Calling a programme in C.

knobby67 · 05-17-2007, 04:30 AM

Hi all,
I need to start a deamon running in my system background before I start up my user code. I was going to run it through a start up script, however thought it might be better to start it up from with in my code. Could anyone advise if this can be done in C.
Thanks

nc3b · 05-17-2007, 04:41 AM

system(), popen() or exec()

sibtay · 05-17-2007, 08:58 AM

fork() and then exec. man exec, man fork for more details

elyk1212 · 05-19-2007, 11:32 AM

Yes, however, look at all the details of each method (as mentioned above). A fork then exec will allocate a whole new process memory space and executes a copy of your code with that program counter value at the time of the fork. Kind of like a new thread, but a whole new process memory space. If that is what you want, that is the way to go.

sibtay · 05-19-2007, 11:52 AM

Quote:

Originally Posted by elyk1212

Yes, however, look at all the details of each method (as mentioned above). A fork then exec will allocate a whole new process memory space and executes a copy of your code with that program counter value at the time of the fork. Kind of like a new thread, but a whole new process memory space. If that is what you want, that is the way to go.

Ofcourse, a new process space will be allocated as a result of fork and then exec would cause that space to be replaced with the daemon's copy. But that is what he wanted right? run a daemon/background *process*.

Thanks

kshkid · 05-19-2007, 02:29 PM

Quote:

A fork then exec will allocate a whole new process memory space and executes a copy of your code with that program counter value at the time of the fork. Kind of like a new thread, but a whole new process memory space. If that is what you want, that is the way to go.

The copy of code will be executed only till the point there is an exec command.

After executing the exec command, the execution of code is in its own.

And the creation of a thread and to that of a process is completely different.