Arun, i suggest that if you are using this for IPC then , better use pipes.
And if you really want to use fd in another application then
pass the file descriptor to exec after doing a fork.
something like this.
in application_1
ret = fork();
if(ret == 0){
sprintf(buff, "%d", fd_1);
(void)exec("application_2","application_2", buff, (char*)0);
}
.......
.........
in application_2
int fd_1;
sscanf(argv[1],"%d", &fd_1);
read(fd_1, buff, BUFFSIZE);
....
.....
I hope that helps.
On Wed, Apr 22, 2009 at 7:12 PM, Greg Freemyer <greg.freemyer@xxxxxxxxx> wrote:
> On Wed, Apr 22, 2009 at 5:12 AM, Arun raj <arun.raj.linux@xxxxxxxxx> wrote:
>>
>> On Wed, Apr 22, 2009 at 5:56 PM, pradeep singh <pradeep.rautela@xxxxxxxxx>
>> wrote:
>>>
>>> On Wed, Apr 22, 2009 at 1:33 PM, Arun raj <arun.raj.linux@xxxxxxxxx>
>>> wrote:
>>> > Hello All,
>>> >
>>> > I want to use the file descriptor opened by application_1 in another
>>> > application_2, i.e
>>> >
>>> > ./application_1 :
>>> > main()
>>> > {
>>> > fd_1 = open( file );
>>> > return fd_1;
>>> > }
>>> >
>>> > ./application_2 fd_1
>>> > main()
>>> > {
>>> > ret = read( fd_1 );
>>> > return fd;
>>> > }
>>> >
>>> > My concern is once application_1 main returns all open fds will be
>>> > closed
>>> > right ?
>>>
>>> Right. So better try to fork a new process or create a new thread,
>>> that way you may share the same fd between them.
>>> Once you have the fd, do whatever you want to do with it.
>>>
>>> Si this what you want ?
>>>
>>> HTH
>>> >
>>> > Thanks in advance .
>>> >
>>> > Thanks,
>>> > A.R
>>> >
>>> >
>>>
>>>
>>>
>>> --
>>> Pradeep
> <moved below to eliminate top post>
>> Thanks a lot pradip.
>>
>> I would like to know is there any method/mechanism/logic to share
>> fd opened by application_1 which can be used in application_2.
>>
> You mean in addition to Pradeep's recommendation of "fork() and
> exec()" and multithreading?
>
> As Sandeep said you can pass an open file descriptor across a pipe.
>
> Also, system() is a specialized version of fork & exec that shares
> only stdin, stdout, stderr.
>
> So you have at least 4 ways to do it,
>
> FYI: I'm not sure why this discussion is happening on this mailing
> list. This list is about modifying the kernel, not making calls into
> it.
>
> Greg
> --
> Greg Freemyer
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