Using tar to archive
The program tar (originally for tape archive) is useful
for archiving and transmitting files. For example, you may want to
'tar up' all your work for a course on the acpub
and save it to your own computer's disk drive so you don't run into
quota problems. You might also want to submit (e.g., for cps 108 or
cps 100) an entire directory at once rather than the individual files
in the directory. The tar program is useful for these and other tasks
and is simple to use.
You can see more information by reading the man page, type man tar
The examples below are not meant to be exhaustive.
Note: on the acpub system you probably want to use
/afs/acpub/projct/cps/bin/tar since it understands the z
option. You can use gtar instead.
Create, Extract, See Contents
The tar program takes one of three funcion command line
arguments (there are two others I won't talk about).
(the other options are u for update and r for replace,
see the man page for details).
- c --- to create a tar file, writing the
file starts at the beginning.
- t --- table of contents, see the names of
all files or those specified in other command line arguments.
- x --- extract (restore) the contents of
the tar file.
Exactly one function argument, c, t, x, is used in conjunction with
other command line arguments shown below. Again, these examples are not
meant to be complete, just useful.
Compression, Verbose, File specified
In addition to a function command line argument the arguments below are
useful. I usually use z and f all the
time, and v when creating/extracting.
- f --- specifies the filename (which
follows the f) used to tar into or to tar out from; see the
- z --- use zip/gzip to compress the tar
file or to read from a compressed tar file.
- v --- verbose output, show, e.g., during create
or extract, the files being stored into or restored from the
To tar all .cc and .h files into a tar file named foo.tgz use:
tar cvzf foo.tgz *.cc *.h
This creates (c) a compressed (z) tar file named foo.tgz (f)
and shows the files being stored into the tar file (v). The
.tgz suffix is a convention for gzipped tar files, it's useful
to use the convention since you'll know to use z to restore/extract.
It's often more useful to tar a directory (which tars all files and
subdirectories recursively unless you specify otherwise). The nice part
about tarring a directory is that it is untarred as a directory
rather than as individual files.
tar cvzf foo.tgz cps100
will tar the directory cps100 (and its files/subdirectories) into a tar
file named foo.tgz.
To see a tar file's table of contents use:
tar tzf foo.tgz
To extract the contents of a tar file use:
tar xvzf foo.tgz
This untars/extracts (x) into the directory from which the command is
invoked, and prints the files being extracted (v).
If you want to untar into a specified directory, change into that
directory and then use tar. For example, to untar into a directory named
tar xvzf ../foo.tgz
You can extract only one (or several) files if you know the name of the
file. For example, to extract the file named anagram.cc from
the tarfile foo.tgz:
tar xvzf foo.tgz anagram.cc
Other Archiving/Compression Tools
Many PC/Mac programs will be able to restore files that have been
archived using tar. For example, on Macs, the Stuffit Deluxe program
can handle Unix tar files. On PCs, the pkunzip program will handle Unix
tar files. This makes it possible to tar files up on acpub and then use
ftp to bring them to your personal machine where you can store the tar
files and restore when needed. Of course you can run Linux too.
The zip and unzip commands available on acpub and CS
systems, are very useful replacements for tar. Zip/unzip programs are
nearly standard on Windows 95/NT machines and zip will archive entire
directory structures with the right options (type zip by itself
Owen L. Astrachan
Last modified: Wed Jan 21 13:49:40 EST 1998