Q:

merge all tar files on mac

I have a bunch of tar files such as a.tar b.tar. I use the following command to merge two tar files :
tar --concatenate --file=a.tar b.tar

However, --concatenate is not support on mac terminal 10.7.4 . What I need to do ?

A:

There's a wonderful notion in the tar realm called a tar-ball. Basically it behaves very much the same way a real tarball would. It's sticky and you can throw stuff at it and it will stick!
So the basic Tar usage is:
tar --file=path_to_tarball  --subcommand [--subcommand] \
         [path_to_payload [path_to_payload]]
now let's see it in an example. 
tar --file=Merged.tar --create file1.txt file2.txt
This creates a tarball of the 2 files file1 and file2. As i said earlier you can throw things at the tarball and it will still be fine!
tar --file=Merged.tar --append file3.txt
So as you can see the tarball just gets bigger and bigger!
Since you can imagine this to be a rather big ball lying around after some time, perhaps you want to retrieve something from it after a while? Or maybe even delete it?
To extract a file out of the tar ball we have
tar --file=Merge.tar --extract fileX.txt
and to delete it
tar --file=Megre.tar --delete fileX.txt
for a list of other awesome things you can do with the tar tool, head on over to MacTech

