UNIX for Dummies Questions & Answers

Hey all

I've got a tar file. In this tar file is heaps of stuff. Also including full directories.
Now though some of the files in that tar file have changed. So what I would like to do is to replace those files then tar it all up again. BUT I want to do this in a temp directpry cause some of these files are system files for anything configuration.

Is there a way that I can replace a file in a tar file?

or

Untar the tar file in a tmp directory? (I can't get that to work without it placing files back in there directory which I don't want) replace the files I have to, then tar it back up again. But when I tar it up again it'll keep the same structure including the directories?


Thx for any help!

I don't think there is any option in tar to replace files which have been modified since they were last written in the archive.

Although there is an option "u" which will let you do the other way, i.e., to add a file if it is not already present or has been modified since it was last written in the archive.

Though you can overwrite the whole of the archive with the existing directory structure using the c option.

I would like to see if there are any simple solutions to this.

Cheers!
Vishnu.

I see the same limitations with my copy of tar (GNU Tar)...
You could probably script something together that would allow you to find the modifications (using the "-d" option), then append (using "-r"), but that would do the same as "-u", update.

In that case it simply appends the changed files on the end of the archive, but does not delete the first version(s) from the archive...

Also, I'm assuming you're using the "-P" option to preserve the leading / on filenames... if not, you may be able to extract to another filesystem/directory. You can use the "-t" option to list out the files to make sure... Then, you could unpack, compare and update, then repack...

Have you though about using a different backup strategy, such as "dump" (if it's available to you - what Unix are you using?)

Ok maybe I should have explained a little of what I'm doing. Sorry my mistake.

LivinFree, As the above says my mistake. It's not for a backup so dump wouldn't be an option.


This is what the CD is used for, anauto install CD for their software for the customer.

So I've created a simple little script and one huge tar file with all the files and even directories if needed. When the script is run teh files and directories are done and everyting works fine providing I tar'ed it all up right.

But now I have come across A problem. But now with updates to the software and only a few little files changed he doesn't want to go through all the stuff I do now to update a CD. cause at this time I have to untar it all then replace the files and tar it all up again. Well now I also know of a few more patches that will happen later on.

So I was just wondering if there was a way I could update the files in the tar without having to untar the file.

Ok yes I know I might have to untar the file, BUT is there a way I can untar the file in the /tmp keeping the locations of the directories BUT NOT putting them in there. So the /etc/hosts file for example would be shown from the tar file when untared as /tmp/etc/hosts. But when I replace the files and tar it back up I don't want to tar up the /tmp directory, I still want it to untar when it's from the CD and replace the old system files with the new ones and the files our software uses.