Is a mmaped file considered an open file in linux/unix?
0
Hi I feel confused about open file and mmapped file. I know that if a file is accessed using system call such as read/write will return a file descriptor, and be considered as an open file? How about a mmaped file?
Thanks,
linux filesystems file-descriptors mmap
asked Mar 5 at 7:57
Mao YeMao Ye
41
add a comment |
0
Hi I feel confused about open file and mmapped file. I know that if a file is accessed using system call such as read/write will return a file descriptor, and be considered as an open file? How about a mmaped file?
Thanks,
linux filesystems file-descriptors mmap
asked Mar 5 at 7:57
Mao YeMao Ye
41
" I know that if a file is accessed using system call such as read/write will return a file descriptor," ... don't you need a file descriptor to usereadorwritein the first place? This question is confusing.
– Olorin
Mar 5 at 8:16
See this answer to another question about mmap. You need an open file descriptor to call mmap, but after that the kernel will use a hidden descriptor and you can close the file descriptor you opened. The memory mapped by mmap will continue to be available.
– Mark Plotnick
Mar 5 at 10:51
add a comment |
0
0
0
Hi I feel confused about open file and mmapped file. I know that if a file is accessed using system call such as read/write will return a file descriptor, and be considered as an open file? How about a mmaped file?
Thanks,
linux filesystems file-descriptors mmap
asked Mar 5 at 7:57
Mao YeMao Ye
41
Hi I feel confused about open file and mmapped file. I know that if a file is accessed using system call such as read/write will return a file descriptor, and be considered as an open file? How about a mmaped file?
Thanks,
linux filesystems file-descriptors mmap
linux filesystems file-descriptors mmap
asked Mar 5 at 7:57
Mao YeMao Ye
41
asked Mar 5 at 7:57
Mao YeMao Ye
41
asked Mar 5 at 7:57
Mao YeMao Ye
41
asked Mar 5 at 7:57
Mao YeMao Ye
41
asked Mar 5 at 7:57
Mao YeMao Ye
41
41
" I know that if a file is accessed using system call such as read/write will return a file descriptor," ... don't you need a file descriptor to usereadorwritein the first place? This question is confusing.
– Olorin
Mar 5 at 8:16
See this answer to another question about mmap. You need an open file descriptor to call mmap, but after that the kernel will use a hidden descriptor and you can close the file descriptor you opened. The memory mapped by mmap will continue to be available.
– Mark Plotnick
Mar 5 at 10:51
add a comment |
" I know that if a file is accessed using system call such as read/write will return a file descriptor," ... don't you need a file descriptor to usereadorwritein the first place? This question is confusing.
– Olorin
Mar 5 at 8:16
See this answer to another question about mmap. You need an open file descriptor to call mmap, but after that the kernel will use a hidden descriptor and you can close the file descriptor you opened. The memory mapped by mmap will continue to be available.
– Mark Plotnick
Mar 5 at 10:51
" I know that if a file is accessed using system call such as read/write will return a file descriptor," ... don't you need a file descriptor to use
read or write in the first place? This question is confusing.– Olorin
Mar 5 at 8:16
" I know that if a file is accessed using system call such as read/write will return a file descriptor," ... don't you need a file descriptor to use
read or write in the first place? This question is confusing.– Olorin
Mar 5 at 8:16
See this answer to another question about mmap. You need an open file descriptor to call mmap, but after that the kernel will use a hidden descriptor and you can close the file descriptor you opened. The memory mapped by mmap will continue to be available.
– Mark Plotnick
Mar 5 at 10:51
See this answer to another question about mmap. You need an open file descriptor to call mmap, but after that the kernel will use a hidden descriptor and you can close the file descriptor you opened. The memory mapped by mmap will continue to be available.
– Mark Plotnick
Mar 5 at 10:51
add a comment |
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" I know that if a file is accessed using system call such as read/write will return a file descriptor," ... don't you need a file descriptor to use
readorwritein the first place? This question is confusing.– Olorin
Mar 5 at 8:16
See this answer to another question about mmap. You need an open file descriptor to call mmap, but after that the kernel will use a hidden descriptor and you can close the file descriptor you opened. The memory mapped by mmap will continue to be available.
– Mark Plotnick
Mar 5 at 10:51