1README for GNU tar
2See the end of file for copying conditions.
3
4* Introduction
5
6Please glance through *all* sections of this
7`README' file before starting configuration. Also make sure you read files
8`ABOUT-NLS' and `INSTALL' if you are not familiar with them already.
9
10If you got the `tar' distribution in `shar' format, time stamps ought to be
11properly restored; do not ignore such complaints at `unshar' time.
12
13GNU `tar' saves many files together into a single tape or disk
14archive, and can restore individual files from the archive. It includes
15multivolume support, the ability to archive sparse files, automatic archive
16compression/decompression, remote archives and special features that allow
17`tar' to be used for incremental and full backups. This distribution
18also includes `rmt', the remote tape server. The `mt' tape drive control
19program is in the GNU `cpio' distribution.
20
21GNU `tar' is derived from John Gilmore's public domain `tar'.
22
23See file `ABOUT-NLS' for how to customize this program to your language.
24See file `COPYING' for copying conditions.
25See file `INSTALL' for compilation and installation instructions.
26See file `PORTS' for various ports of GNU tar to non-Unix systems.
27See file `NEWS' for a list of major changes in the current release.
28See file `THANKS' for a list of contributors.
29
30Besides those configure options documented in files `INSTALL' and
31`ABOUT-NLS', an extra option may be accepted after `./configure':
32
33* Install
34
35** Selecting the default archive format.
36
37The default archive format is GNU, this can be overridden by
38presetting DEFAULT_ARCHIVE_FORMAT while configuring. The allowed
39values are GNU, V7, OLDGNU, USTAR and POSIX.
40
41** Selecting the default archive device
42
43The default archive device is now `stdin' on read and `stdout' on write.
44The installer can still override this by presetting `DEFAULT_ARCHIVE'
45in the environment before configuring (the behavior of `-[0-7]' or
46`-[0-7]lmh' options in `tar' are then derived automatically). Similarly,
47`DEFAULT_BLOCKING' can be preset to something else than 20.
48
49** Selecting full pathname of the "rmt" binary.
50
51Previous versions of tar always looked for "rmt" binary in the
52directory "/etc/rmt". However, the "rmt" program included
53in the distribution was installed under "$prefix/libexec/rmt".
54To fix this discrepancy, tar now looks for "$prefix/libexec/rmt".
55If you do not want this behavior, specify full path name of
56"rmt" binary using DEFAULT_RMT_DIR variable, e.g.:
57
58./configure DEFAULT_RMT_DIR=/etc
59
60If you already have a copy of "rmt" installed and wish to use it
61instead of the version supplied with the distribution, use --with-rmt
62option:
63
64./configure --with-rmt=/etc/rmt
65
66This will also disable building the included version of rmt.
67
68** Installing backup scripts.
69
70This version of tar is shipped with the shell scripts for producing
71incremental backups (dumps) and restoring filesystems from them.
72The name of the backup script is "backup". The name of the
73restore script is "restore". They are installed in "$prefix/sbin"
74directory.
75
76Use option --enable-backup-scripts to compile and install these
77scripts.
78
79** `--disable-largefile' omits support for large files, even if the
80operating system supports large files. Typically, large files are
81those larger than 2 GB on a 32-bit host.
82
83* Installation hints
84
85Here are a few hints which might help installing `tar' on some systems.
86
87** gzip and bzip2.
88
89GNU tar uses the gzip and bzip2 programs to read and write compressed
90archives. If you don't have these programs already, you need to
91install them. Their sources can be found at:
92
93ftp://ftp.gnu.org/gnu/gzip/
94http://sourceware.cygnus.com/bzip2/
95
96If you see the following symptoms:
97
98 $ tar -xzf file.tar.gz
99 gzip: stdin: decompression OK, trailing garbage ignored
100 tar: Child returned status 2
101
102then you have encountered a gzip incompatibility that should be fixed
103in gzip test version 1.3, which as of this writing is available at
104<ftp://alpha.gnu.org/gnu/gzip/>. You can work around the
105incompatibility by using a shell command like
106 `gzip -d <file.tar.gz | tar -xzf -'.
107
108** Solaris issues.
109
110GNU tar exercises many features that can cause problems with older GCC
111versions. In particular, GCC 2.8.1 (sparc, -O1 or -O2) is known to
112miscompile GNU tar. No compiler-related problems have been reported
113when using GCC 2.95.2 or later.
114
115Recent versions of Solaris tar sport a new -E option to generate
116extended headers in an undocumented format. GNU tar does not
117understand these headers.
118
119** Static linking.
120
121Some platform will, by default, prepare a smaller `tar' executable
122which depends on shared libraries. Since GNU `tar' may be used for
123system-level backups and disaster recovery, installers might prefer to
124force static linking, making a bigger `tar' executable maybe, but able to
125work standalone, in situations where shared libraries are not available.
126The way to achieve static linking varies between systems. Set LDFLAGS
127to a value from the table below, before configuration (see `INSTALL').
128
129 Platform Compiler LDFLAGS
130
131 (any) Gnu C -static
132 AIX (vendor) -bnso -bI:/lib/syscalls.exp
133 HPUX (vendor) -Wl,-a,archive
134 IRIX (vendor) -non_shared
135 OSF (vendor) -non_shared
136 SCO 3.2v5 (vendor) -dn
137 Solaris (vendor) -Bstatic
138 SunOS (vendor) -Bstatic
139
140** Failed tests `ignfail.sh' or `incremen.sh'.
141
142In an NFS environment, lack of synchronization between machine clocks
143might create difficulties to any tool comparing dates and file time stamps,
144like `tar' in incremental dumps. This has been a recurrent problem with
145GNU Make for the last few years. We would like a general solution.
146
147** BSD compatibility matters.
148
149Set LIBS to `-lbsd' before configuration (see `INSTALL') if the linker
150complains about `bsd_ioctl' (Slackware). Also set CPPFLAGS to
151`-I/usr/include/bsd' if <sgtty.h> is not found (Slackware).
152
153** OPENStep 4.2 swap files
154
155Tar cannot read the file /private/vm/swapfile.front (even as root).
156This file is not a real file, but some kind of uncompressed view of
157the real compressed swap file; there is no reason to back it up, so
158the simplest workaround is to avoid tarring this file.
159
160* Special topics
161
162Here are a few special matters about GNU `tar', not related to build
163matters. See previous section for such.
164
165** File attributes.
166
167About *security*, it is probable that future releases of `tar' will have
168some behavior changed. There are many pending suggestions to choose from.
169Today, extracting an archive not being `root', `tar' will restore suid/sgid
170bits on files but owned by the extracting user. `root' automatically gets
171a lot of special privileges, `-p' might later become required to get them.
172
173GNU `tar' does not properly restore symlink attributes. Various systems
174implement flavors of symbolic links showing different behavior and
175properties. We did not successfully sorted all these out yet. Currently,
176the `lchown' call will be used if available, but that's all.
177
178** POSIX compliance.
179
180GNU `tar' is able to create archive in the following formats:
181
182 *** The format of UNIX version 7
183 *** POSIX.1-1988 format, also known as "ustar format"
184 *** POSIX.1-2001 format, also known as "pax format"
185 *** Old GNU format (described below)
186
187In addition to those, GNU `tar' is also able to read archives
188produced by `star' archiver.
189
190A so called `Old GNU' format is based on an early draft of the
191POSIX 1003.1 `ustar' standard which is different from the final
192standard. It defines its extensions (such as incremental backups
193and handling of the long file names) in a way incompatible with
194any existing tar archive format, therefore the use of old GNU
195format is strongly discouraged.
196
197Please read the file NEWS for more information about POSIX compliance
198and new `tar' features.
199
200* What's next?
201
202GNU tar will be merged into GNU paxutils: a project containing
203several utilities related to creating and handling archives in
204various formats. The project will include tar, cpio and pax
205utilities.
206
207* Bug reporting.
208
209Send bug reports to <bug-tar@gnu.org>. A bug report should contain
210an adequate description of the problem, your input, what you expected,
211what you got, and why this is wrong. Diffs are welcome, but they only
212describe a solution, from which the problem might be uneasy to infer.
213If needed, submit actual data files with your report. Small data files
214are preferred. Big files may sometimes be necessary, but do not send them
215to the report address; rather take special arrangement with the maintainer.
216
217Your feedback will help us to make a better and more portable package.
218Consider documentation errors as bugs, and report them as such. If you
219develop anything pertaining to `tar' or have suggestions, let us know
220and share your findings by writing to <bug-tar@gnu.org>.
221
222
223* Copying
224
225 Copyright (C) 1990, 1991, 1992, 1994, 1997, 1998, 1999, 2000,
226 2001, 2003, 2004 Free Software Foundation, Inc.
227
228 This file is part of GNU tar.
229
230 GNU tar is free software; you can redistribute it and/or modify
231 it under the terms of the GNU General Public License as published by
232 the Free Software Foundation; either version 2, or (at your option)
233 any later version.
234
235 GNU tar is distributed in the hope that it will be useful,
236 but WITHOUT ANY WARRANTY; without even the implied warranty of
237 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
238 GNU General Public License for more details.
239
240 You should have received a copy of the GNU General Public License
241 along with tar; see the file COPYING. If not, write to
242 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
243 Boston, MA 02110-1301, USA.
244
245
246Local Variables:
247mode: outline
248paragraph-separate: "[ ]*$"
249version-control: never
250End:
251
252