Linux: how to mark a file descriptor as not inheritable on fork?

Question

Is it possible to mark a specific file descriptor as not inheritable, or close it, in the child process when fork() is invoked?

Possible duplicate of [Prevent file descriptors inheritance during Linux fork](https://stackoverflow.com/q/5713242/608639) — jww, Apr 18 '19 at 18:06

score 10 · Accepted Answer · answered Jul 06 '11 at 15:59

10

No. All file descriptors are inherited in fork. You can set a fd to be closed on exec, however, by using fcntl(fd, F_SETFD, FD_CLOEXEC).

answered Jul 06 '11 at 15:59

bdonlan

3

Also note that you can save the `fcntl` by passing `O_CLOEXEC` to `open` under Linux. – Damon Jul 06 '11 at 17:04
1

@Damon: Or any POSIX 2008 conformant system (`O_CLOEXEC` was standardized with POSIX 2008). – R.. GitHub STOP HELPING ICE Aug 29 '11 at 14:52

score 0 · Answer 2 · answered Jul 06 '11 at 16:44

0

No its not possible. By default child processes with inherit file table from parent process.

answered Jul 06 '11 at 16:44

CrazyCoder

score 0 · Answer 3 · answered Aug 29 '11 at 14:51

0

If you really want close-on-fork, something like this could work:

static void fd_to_close;
static void closer()
{
    close(fd_to_close);
}

pthread_atfork(0, 0, closer);

Normally close-on-exec is the desired behavior anyway, though.

answered Aug 29 '11 at 14:51

3 Answers3