tar problem

UNIX for Advanced & Expert Users
1

I am using a tar command to backup my system. It works properly.

I have had some trouble and I need to restore a few files.

I am using the following command :

tar xvf /dev/rmt2h myfile_to_restore

The tar command seemd to work but after a long time I got the following error message :
tar: /dev/rmt2h : this doesn't look like a tar archive
tar: /dev/rmt2h : Skipping to next file...
tar: Memory allocation failed for extended data while reading : Invalid argument.

If I am using the command
tar xvf /dev/rmt2h
without any procision of a specific file, then it works and extract everything ... But I just would like to extract a few files...

Any idees?
I am working on True64 Unix V4.0e
Thanks

2

Shouldnt there be a / after rmt. /dev/rmt/2h ?

3

No the command
tar xvf /dev/rmt2h is correct and has always worked. The problem is linked to the fact that I speciified a file to extract. I don't anderstand why the tar command failed with such message.

If anyone has other ideas?
Thanx

4

Why not extract the tar file into somewhere like /tmp then just grab the file you want?

5

That's what I am doing, but as I have not enough space on my disk to restore the whole backup I have to watch all the restore to delete the files I don't need.
It is a little tedious, and I can't restore the files I want during the night for example.

6

Try
tar --extract --file=nameoftar.tar name_of_file_to_extract

7

This syntax does not work.
It is either tar xf ... or tar -xf (which is an old syntax which will not be supported in the future).

But, I think i found the problem. It was a question of naming the "file_to_extract". It must be exactly as it has been named in the tar file. I though that I could say
tar xf /dev/rmt2h my_file_to extract
even if in the backup the file was backed up as ./my_file_to extract

So now, if I type :
tar xf /dev/rmt2h ./my_file_to extract
it works ...
Thanks to all of you who tried to help me