tar/README

Please glance through *all* sections of this
`README' file before starting configuration.  Also make sure you read files
`ABOUT-NLS' and `INSTALL' if you are not familiar with them already.

If you got the `tar' distribution in `shar' format, timestamps ought to be
properly restored, do not ignore such complaints at `unshar' time.

GNU `tar' saves many files together into a single tape or disk
archive, and can restore individual files from the archive.  It includes
multivolume support, the ability to archive sparse files, automatic archive
compression/decompression, remote archives and special features that allow
`tar' to be used for incremental and full backups.  This distribution
also includes `rmt', the remote tape server.  The `mt' tape drive control
program is in the GNU `cpio' distribution.

GNU `tar' is derived from John Gilmore's public domain `tar'.

See file `ABOUT-NLS' for how to customize this program to your language.
See file `BACKLOG' for a summary of pending mail and articles.
See file `COPYING' for copying conditions.
See file `INSTALL' for compilation and installation instructions.
See file `PORTS' for various ports of GNU tar to non-Unix systems.
See file `NEWS' for a list of major changes in the current release.
See file `THANKS' for a list of contributors.

Besides those configure options documented in files `INSTALL' and
`ABOUT-NLS', a few extra options may be accepted after `./configure':

* `--with-dmalloc' is a debugging option for looking at memory management
problems, it prerequires Gray Watson's package, which is available as
`ftp://ftp.letters.com/src/dmalloc/dmalloc.tar.gz'.

The default archive device is now `stdin' on read and `stdout' on write.
The installer can still override this by presetting `DEFAULT_ARCHIVE'
in the environment before configuring (the behavior of `-[0-7]' or
`-[0-7]lmh' options in `tar' are then derived automatically).  Similarly,
`DEFAULT_BLOCKING' can be preset to something else than 20.

For comprehensive modifications to GNU tar, you might need tools beyond
those used in simple installations.  Fully install GNU m4 1.4 first,
and only then, Autoconf 2.13 or later.  Install Perl, then Automake
1.4 or later.  You might need Bison 1.26 or later, and GNU tar itself.
All are available on GNU archive sites, like in
ftp://ftp.gnu.org/pub/gnu/.

Send bug reports to `bug-tar@gnu.org'.  (Beware, old-timers: it is
`@gnu', not `@prep'; and not `bug-gnu-utils' anymore.)  A bug report is
an adequate description of the problem: your input, what you expected,
what you got, and why this is wrong.  Diffs are welcome, but they only
describe a solution, from which the problem might be uneasy to infer.
If needed, submit actual data files with your report.  Small data files
are preferred.  Big files may sometimes be necessary, but do not send them
to the report address; rather take special arrangement with the maintainer.

Your feedback will help us to make a better and more portable package.
Consider documentation errors as bugs, and report them as such.  If you
develop anything pertaining to `tar' or have suggestions, let us know
and share your findings by writing at `tar-forum@iro.umontreal.ca'.

.--------------------.
| Installation hints |
`--------------------'

Here are a few hints which might help installing `tar' on some systems.

* Static linking.

Some platform will, by default, prepare a smaller `tar' executable
which depends on shared libraries.  Since GNU `tar' may be used for
system-level backups and disaster recovery, installers might prefer to
force static linking, making a bigger `tar' executable maybe, but able to
work standalone, in situations where shared libraries are not available.
The way to achieve static linking varies between systems.  Set LDFLAGS
to a value from the table below, before configuration (see `INSTALL').

	Platform	Compiler	LDFLAGS

	(any)		Gnu C		-static
	AIX		(vendor)	"-bnso -bI:/lib/syscalls.exp"
	HPUX		(vendor)	-Wl,-a,archive
	IRIX		(vendor)	-non_shared
	OSF		(vendor)	-non_shared
	SCO 3.2v5	(vendor)	-dn
	Solaris		(vendor)	-Bstatic
	SunOS		(vendor)	-Bstatic

* Failed `incremen.sh'.

In an NFS environment, lack of synchronisation between machine clocks
might create difficulties to any tool comparing dates and file timestamps,
like `tar' in incremental dumps.  This has been a recurrent problem in
GNU Makefiles for the last few years.  We would like a general solution.

* BSD compatibility matters.

Set LIBS to `-lbsd' before configuration (see `INSTALL') if the linker
complains about undefined `valloc' (AIX) or `bsd_ioctl' (Slackware).
Also set CPPFLAGS to `-I/usr/include/bsd/sys' before configuration to
solve dirent problems (NeXT), or to `-I/usr/include/bsd' if <sgtty.h>
is not found (Slackware).

* `union wait' problems.

Configuration of `union wait' does not always take the best decision.
If you have this problem, edit file `config.cache' after configuration,
find the line about `tar_cv_header_union_wait', change `yes' by `no'
or vice-versa, execute `./config.status', then launch `make'.

* `%lld' unsupported in `printf'.

GNU C has `long long', but the underneath C library might not support
the `%lld' format.  If you have this problem, edit file `config.cache'
after configuration, find the line about `ac_cv_sizeof_long_long, change
`8' by `0', execute `./config.status', then launch `make'.

* FreeBSD users -- `configure' fails.

It has been reported that `configure' does not run on FreeBSD 2.1.7,
because of a buggy `sh'.  It works using `bash', however.

* ISC users -- `S_*' symbols undefined.

On ISC 4.1mu, POSIX environment, set CFLAGS to `-posix' and CPPFLAGS to
`-D_SYSV3' before configuration (see `INSTALL').  This will trigger the
definition of a few `S_' prefixed symbols from <sys/stat.h>.

* Ultrix users -- broken `make'.

It seems that Ultrix make does not correctly handle shell commands
having logical connectives in them.  Use `s5make' if you have it, try
`PROG_ENV=SYSTEM_FIVE make' (works on Ultrix 4.4), or install GNU Make.

.------------------.
| Special topics.  |
`------------------'

Here are a few special matters about GNU `tar', not related to build
matters.  See previous section for such.

* File attributes.

About *security*, it is probable that future releases of `tar' will have
some behaviour changed.  There are many pending suggestions to choose from.
Today, extracting an archive not being `root', `tar' will restore suid/sgid
bits on files but owned by the extracting user.  `root' automatically gets
a lot of special priviledges, `-p' might later become required to get them.

GNU `tar' does not properly restore symlink attributes.  Various systems
implement flavours of symbolic links showing different behaviour and
properties.  We did not successfully sorted all these out yet.  Currently,
the `lchown' call will be used if available, but that's all.

* POSIX compliance.

GNU `tar' implements an early draft of the POSIX 1003.1 `ustar' standard
which is different from the final standard.  This will be progressively
corrected over the incoming few years.  Don't be mislead by the mere
existence of the --posix option.  Later releases will become able to
read truly POSIX archives, and also to produce them under option.  (Also,
if you look at the internals, don't take the GNU extensions you see for
granted, as they are planned to change.)  GNU tar 2.0 will produce POSIX
archives by default, but there is a long way before we get there.

* What's next?

The emphasis from 1.11.2 to 1.12 has been on solving the main portability,
execution or usability bugs.  This was accompanied all over with an
internal cleanup in the sources, and the reassembly of a `tar' manual.

The `BACKLOG' file shows an approximative priorisation of the many pending
problems and suggestions.  Besides pending problems and all other matters
listed above, the cleanup is planned to continue and extend to the general
organisation of the code, preparing a long time in advance for a possible
merge of the `cpio' and `tar' distributions, into some common `paxutils'.
We also want to address some long-awaited performance issues (for example:
double buffering) or enhancements (for example: per-file compression).