On Wed, May 26, 2010 at 10:16 AM, Rector, David <drector@xxxxxxxxxxxxxx> wrote:
> Hello,
>
> I have studied various filesystems, and am fairly familiar with how they are structured. However, I am currently stuck on trying to do what seems like a simple thing.
>
> I would like to join two files together without having to physically copy bytes (i.e. I have vary large files, so I don't want to use 'cat'). It seems to me that it should be possible to simply modify the file entry in the filesystem such that the last inode of the first file points to the first inode of the second file. I guess this is similar to a "hard link", but used to join files rather than simply have another pointer to one file.
>
> I have seen 'mmv' and 'lxsplit' and they all seem to do the same thing, namely they want to physically copy the bytes in order to join two files together.
>
> Is there any such utility in linux to perform such a hard link to join or connect two files together without having to copy bytes?
>
> Thanks for your help.
>
> Dave Rector
> *:^)
> --
There is no way that this can work as you might expect.
Consider the end of a file. If the allocation block is the
common 4K bytes then the file can end at one of
4096 different byte locations. So even if the BLOCKS could
be joined the bytes cannot.
However in use the common way to deal with this is
to cat multiple files into a pipe and have the program
read the pipe (stream). i.e
# cat file1 file2 file3 | program
You can avoid the copy of bytes in the first file
and copy then append bytes from the second file
onto the first.
# cat file2 >> file1
Programs can open a sequence of files
one after another. Because of this there
is seldom a need to "append" files as
you seem to want.
--
NiftyFedora
T o m M i t c h e l l
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