Untar single file to desired name

Question

When I tar a single file, I can give the tar file a desired name:

$ tar -cvfj A B

I would like to do the same when I untar a single file.

$ tar -xvjf A tmp

(ie. extract A into tmp).

I was trying to do this using mv:

$ tar -xvjf $1 | mv $1 tmp

That didn't work. $1 can be an arbitrary name, but the tar files will always be a single file, no folders (this is guaranteed).

Answer 1

Since you seem to be using tar with bzip2 compression as a way of just compressing a single file, you may want to consider using bzip2 directly:

To compress a file (creates filename.bz2, deletes filename):

bzip2 filename

To decompress a file (creates filename, deletes filename.bz2):

bunzip2 filename.bz2

To compress to a specific filename (creates newfilename.bz2, keeps filename):

bzip2 -c filename >newfilename.bz2

To decompress to a specific filename (creates newfilename, keeps filename.bz2):

bunzip2 -c filename.bz2 >newfilename

See also the manual for bzip2 on your system (man bzip2).

Answer 2

Here is one solution:

tar -xjOf my.tar > out

This uses the -O option of tar

-O, --to-stdout: extract files to standard output

and redirects standard output to a file called out. If the archive has more than one file, out will be all of the files in the archive concatenated.

You should probably just be using bzip2 directly, as during compression it will not store a file tree. Instead, it will simply store the data within the file.