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How do I close file descriptors?
close() closes a file descriptor, so that it no longer refers to any file and may be reused. Any record locks (see fcntl(2)) held on the file it was associated with, and owned by the process, are removed (regardless of the file descriptor that was used to obtain the lock).
Can we close Stdin?
It will not close. Use fclose(stdin) , as stdin itself is a pointer to FILE object. So if you want to use fd (instead of FILE* ), then you’ve to use close from
Can I close Stdin?
you can just fclose(stdin), it will call close() on the file handle.
Which is the correct way to close a file descriptor?
In that aspect, close is a bit like free: it is invalidating the value (file descriptor for close, pointer for free) passed to it. When possible, you could set the file descriptor to -1 (or some other invalid value) after a successful close (2), so code close (fd); fd = -1; for example.
What happens if FD is the last file descriptor?
If fd is the last file descriptor referring to the underlying open file description (see open (2)), the resources associated with the open file description are freed; if the file descriptor was the last reference to a file which has been removed using unlink (2), the file is deleted. close () returns zero on success.
What happens when you close a file handle?
When you call close, you always close the file handle. When a file handle is closed, the reference count on its open file description is decremented. If it goes to zero, the open file description is also released and the reference count on the file itself is decremented. Only if that goes to zero is the kernel’s file structure freed.
How to close a file descriptor in PID 1234?
For the process of pid 1234, use /proc/1234/fd/ & /proc/1234/fdinfo/ to understand its file descriptors and their table, and /proc/1234/maps & /proc/1234/smaps to understand its virtual address space. So if a called function close -s it, you should not use it anymore.