Archive Files with tar

Archive Files with tar

-cf

Remember, tar doesn't compress; it merely archives (the resulting archives are known as tarballs, by the way). Instead, tar uses other programs, such as gzip or bzip2, to compress the archives that tar creates. Even if you're not going to compress the tarball, you still create it the same way with the same basic options: -c (or --create), which tells tar that you're making a tarball, and -f (or --file), which is the specified filename for the tarball.

$ ls -l scott scott  102519 job.txt scott scott 1236574 moby-dick.txt scott scott  508925 paradise_lost.txt $ tar -cf moby.tar *.txt $ ls -l scott scott  102519 job.txt scott scott 1236574 moby-dick.txt scott scott 1853440 moby.tar scott scott  508925 paradise_lost.txt 

Pay attention to two things here. First, add up the file sizes of job.txt, moby-dick.txt, and paradise_lost.txt, and you get 1848018 bytes. Compare that to the size of moby.tar, and you see that the tarball is only 5422 bytes bigger. Remember that tar is an archive tool, not a compression tool, so the result is at least the same size as the individual files put together, plus a little bit for overhead to keep track of what's in the tarball. Second, notice that tar, unlike gzip and bzip2, leaves the original files behind. This isn't a surprise, considering the tar command's background as a backup tool.

What's really cool about tar is that it's designed to compress entire directory structures, so you can archive a large number of files and subdirectories in one fell swoop.

$  ls -lF drwxr-xr-x scott scott 168 moby-dick/ $ ls -l moby-dick/* scott scott  102519 moby-dick/job.txt scott scott 1236574 moby-dick/moby-dick.txt scott scott  508925 moby-dick/paradise_lost.txt moby-dick/bible: scott scott 207254 genesis.txt scott scott 102519 job.txt $ tar -cf moby.tar moby-dick/ $ ls -lF scott scott     168 moby-dick/ scott scott 2170880 moby.tar 

The tar command has been around forever, and it's obvious why: It's so darn useful! But it gets even more useful when you start factoring in compression tools, as you'll see in the next section.