hard links problem: how to delete all pointers to an inode at once?

onufry · 10-11-2007, 07:05 PM

I wonder if there is any quick way to delete all inode pointers at once (or remove the inode itself)?

I tried combining something with "find" but it is way too slow.

Thanks in advance,
onufry

studioj · 10-12-2007, 12:32 PM

there is really no way i know of to follow links backwards. i think that might be for security reasons ? not sure. it would also violate the basic "no special cases" rule.

matthewg42 · 10-12-2007, 01:27 PM

I don't know a quick method to do this. A slow method would be to use find to scan the whole filesystem. The only real optimisation you can do is to note where the volume (partition) is mounted and only search down that tree - hard links cannot link across volumes.

e.g. if you have /dev/sda2 mounted at /home, and you want to find all files which are hard links to /home/matthew/.bashrc, you might do it like this:

Code:

i=$(ls -i /home/matthew/.bashrc |cut -f1 -d" ")
find /home -type f -print0 |xargs -0 ls -i |grep "^$i "

If you want to perform this operation for multiple files, you might want to make a list of all the inode / filenames in one find operation, sort it, find repeated inode numbers and print those. One approach is to create a (sorted) temporary file with the inode and file names, another with the inodes which are found more than once, and then use the join command to print all lines in the first file for each inode in the seconds. Don't forget to clean up your temporary files afterwards.

Code:

tmp=$(mktemp) ; tmp2=$(mktemp)
find /home -type f -print0 |xargs -0 ls -i |sort > $tmp
cut -f1 -d" " $tmp |uniq -d > $tmp2
join $tmp $tmp2
rm -f $tmp $tmp2

JZL240I-U · 10-16-2007, 03:37 AM

If you run the command repeatedly "locate" would be faster than "find", since it is working with an existing database (which can be brought to the newest information of your system by "updatedb").

<edit> "slocate" is said to be more advanced as locate... </edit>

archtoad6 · 10-16-2007, 01:39 PM

Did you consider the "-inum" or "-samefile" option in find?

If you're concerned w/ just one file, they look ideal.

archtoad6 · 11-18-2007, 05:14 PM

onufry,
What did you do?
Did any of our suggestions work?
Do you need more help?

onufry · 11-18-2007, 06:27 PM

sorry i totally forgot about the question since my idea to implement a packet manager for LFS with hard links was proved wrong. To put it short - deleting hard linked files (all inode pointers at once) is to slow (i was looking for solution with constant time). One can modify the file table on the disk to keep record of inode pointers, but...

Anyway thx for suggestions.