Changing inode value of a hardlink Post: 302905670

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Top Forums Shell Programming and Scripting Changing inode value of a hardlink Post 302905670 by Don Cragun on Friday 13th of June 2014 02:06:16 AM

06-13-2014

Registered User

Quote:

Originally Posted by fhill2

is it possible to change the inode value/ file path of a hard link?

Why do you care what i-node number is assigned to a file?

Of course it is possible. All you have to do is figure out the structure of the filesystem used to store the file and dig into the bits on disk and in the kernel's memory (if the file is open, or any of its data is cached) to change the filesystem's idea of what the i-node is for that file. Depending on the filesystem type, that might mean changing a few bits in one location, or it might mean changing lots of blocks. Using this method, you could change the i-node to be any unused i-node number available in that filesystem. (Note that if you don't already know how to do this, it is not something you should even consider trying; if you do it wrong, you may lose all of the data on that filesystem. And, if it is cached in the kernel and you get it wrong there, you may lose all of the data on all of your filesystems.)

More portably, you could copy the file to another name and then rename the new file to have the name of the old file. This will create a new file with a different i-node number and then remove the old link to the old i-node number. Of course, if there were multiple hard links to the old name, the other links will remain unchanged. If you want them to be linked to the new i-node number, you'll have to find all of the old links, unlink them and then link them to the new file. Using this method, the i-node number will be different, but you will not be able to specify what the new i-node number will be.

Don Cragun

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LEARN ABOUT MOJAVE

mount_cd9660

MOUNT_CD9660(8) 					    BSD System Manager's Manual 					   MOUNT_CD9660(8)

NAME

     mount_cd9660 -- mount an ISO-9660 filesystem

SYNOPSIS

     mount_cd9660 [-egjr] [-o options] [-s startsector] special node

DESCRIPTION

     The mount_cd9660 command attaches the ISO-9660 filesystem residing on the device special to the global filesystem namespace at the location
     indicated by node.  This command is normally executed by mount(8) at boot time.

     The options are as follows:

     -e      Enable the use of extended attributes.

     -g      Do not strip version numbers on files.  (By default, if there are files with different version numbers on the disk, only the last one
	     will be listed.)  In either case, files may be opened without explicitly stating a version number.

     -j      Do not use any Joliet extensions included in the filesystem.

     -o      Options are specified with a -o flag followed by a comma separated string of options.  See the mount(8) man page for possible options
	     and their meanings.

     -r      Do not use any Rockridge extensions included in the filesystem.

     -s startsector
	     Start the filesystem at startsector.  Normally, if the underlying device is a CD-ROM drive, mount_cd9660 will try to figure out the
	     last track from the CD-ROM containing data, and start the filesystem there.  If the device is not a CD-ROM, or the table of contents
	     cannot be examined, the filesystem will be started at sector 0.  This option can be used to override the behaviour.  Note that
	     startsector is measured in CD-ROM blocks, with 2048 bytes each.

SEE ALSO

     mount(2), unmount(2), fstab(5), mount(8)

BUGS

     POSIX device node mapping is currently not supported.

     Version numbers are not stripped if Rockridge extensions are in use.  In this case, accessing files that don't have Rockridge names without
     version numbers gets the one with the lowest version number and not the one with the highest.

     There is no ECMA support.

HISTORY

     The mount_cd9660 utility first appeared 4.4BSD.

4th Berkeley Distribution					  March 27, 1994					 4th Berkeley Distribution