inode的设备是什么？

Question

我正在弄乱stat structure 并试图理解它，但是大多数文档都相当神秘，具体来说，我无法理解第一个成员的目的， st_dev ，究竟是什么“ inode <的设备< / em>的“？

Answer 1

In the field st_dev you find a system-dependent number of the device which backs this file. It usually is the major/minor number (combined with makedev(3)) of the block device which contains the filesystem where the file is located on. If the file is a device node, it is the major/minor number of the device itself.

For example:

$ ls -la /dev/null
crw-rw-rw- 1 root root 1, 3 May 17 09:52 /dev/null

st_dev will contain makedev(1,3) (which is 259 on linux), or

for /etc/passwd, st_dev will contain makedev(8,1) (which is 2049 on linux), if the file is located on /dev/sda1.

You can extract the major/minor number with the corresponding macros major(st_dev) and minor(st_dev), as described in the manpage for makedev(3).