Here is how to find links - and a brief look at the UNIX filesystem from the user's viewpoint. Suppose you are given the following:
%ls -li /usr/foo
2076 -rw-r--r-- 3 chris 326 Sep 16 03:23 /usr/foo
In other words, there are three links, and /usr/foo is one of three names for inode ( 1.22 ) 2076. You can find the full names of the other two links by using /etc/ncheck and/or find . However, just knowing the inode number does not tell you everything.
The whole truth is that there is another number hiding away in there. This is the device number , and it tells which filesystem holds the file. There can be any number of inode 2076s, as long as each one is on a different filesystem. (More recent UNIX systems use a filesystem ID number in place of a device number, so that they can represent filesystems on other machines. They may also use a vnode number rather than an inode number. The effect is the same, although you often cannot run /etc/ncheck on anything but a local disk.)
You can find out which filesystem /usr/foo is in by running df ( 24.9 ) or mount . Suppose it is on /dev/sd0g . If /dev/sd0g shows up as:
%df
Filesystem kbytes used avail capacity Mounted on /dev/sd0g 179423 152202 9278 94% /usr %ls -l /dev/sd0g
brw------ 1 root 2, 6 Dec 27 07:17 /dev/sd0g
then it is "major device 2, minor device 6." These numbers are smashed together with the
makedev
macro in one of the kernel source files. Typically this is just
major
*256 +
minor
; here we have 2*256+6, or 518. Another way to find this same number is to use the
stat
(2) system call on the original file
/usr/foo
; the device number appears in the
st_dev
field. [The
stat
(
21.13
)
program does this for you.
-JP
]
So if you do a
find / -inum 2076 -print
to find every file with inode number 2076, you may find more than three files. Only three of them will be on
sd0g
, though.
- in net.unix on Usenet, 15 January 1985