Dogcows Code - chaz/tar/blob - README

   1 README for GNU tar
   2
   3         Copyright 1990, 1991, 1992, 1994, 1997, 1998, 1999, 2000, 2001
   4         Free Software Foundation, Inc.
   5
   6         This file is part of GNU tar.
   7
   8         GNU tar is free software; you can redistribute it and/or modify
   9         it under the terms of the GNU General Public License as published by
  10         the Free Software Foundation; either version 2, or (at your option)
  11         any later version.
  12
  13         GNU tar is distributed in the hope that it will be useful,
  14         but WITHOUT ANY WARRANTY; without even the implied warranty of
  15         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16         GNU General Public License for more details.
  17
  18         You should have received a copy of the GNU General Public License
  19         along with tar; see the file COPYING.  If not, write to
  20         the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  21         Boston, MA 02111-1307, USA.
  22
  23
  24 Please glance through *all* sections of this
  25 `README' file before starting configuration.  Also make sure you read files
  26 `ABOUT-NLS' and `INSTALL' if you are not familiar with them already.
  27
  28 If you got the `tar' distribution in `shar' format, time stamps ought to be
  29 properly restored; do not ignore such complaints at `unshar' time.
  30
  31 GNU `tar' saves many files together into a single tape or disk
  32 archive, and can restore individual files from the archive.  It includes
  33 multivolume support, the ability to archive sparse files, automatic archive
  34 compression/decompression, remote archives and special features that allow
  35 `tar' to be used for incremental and full backups.  This distribution
  36 also includes `rmt', the remote tape server.  The `mt' tape drive control
  37 program is in the GNU `cpio' distribution.
  38
  39 GNU `tar' is derived from John Gilmore's public domain `tar'.
  40
  41 See file `ABOUT-NLS' for how to customize this program to your language.
  42 See file `COPYING' for copying conditions.
  43 See file `INSTALL' for compilation and installation instructions.
  44 See file `PORTS' for various ports of GNU tar to non-Unix systems.
  45 See file `NEWS' for a list of major changes in the current release.
  46 See file `THANKS' for a list of contributors.
  47
  48 Besides those configure options documented in files `INSTALL' and
  49 `ABOUT-NLS', an extra option may be accepted after `./configure':
  50
  51 * `--disable-largefile' omits support for large files, even if the
  52 operating system supports large files.  Typically, large files are
  53 those larger on 2 GB on a 32-bit host.
  54
  55 The default archive device is now `stdin' on read and `stdout' on write.
  56 The installer can still override this by presetting `DEFAULT_ARCHIVE'
  57 in the environment before configuring (the behavior of `-[0-7]' or
  58 `-[0-7]lmh' options in `tar' are then derived automatically).  Similarly,
  59 `DEFAULT_BLOCKING' can be preset to something else than 20.
  60
  61 For comprehensive modifications to GNU tar, you might need tools beyond
  62 those used in simple installations.  Fully install GNU m4 1.4 first,
  63 and only then, Autoconf 2.13 or later.  Install Perl, then Automake
  64 1.4 or later.  You might need Bison 1.28 or later, and GNU tar itself.
  65 All are available on GNU archive sites, like in
  66 ftp://ftp.gnu.org/pub/gnu/.
  67
  68 Send bug reports to `bug-tar@gnu.org'.  (Beware, old-timers: it is
  69 `@gnu', not `@prep'; and not `bug-gnu-utils' anymore.)  A bug report is
  70 an adequate description of the problem: your input, what you expected,
  71 what you got, and why this is wrong.  Diffs are welcome, but they only
  72 describe a solution, from which the problem might be uneasy to infer.
  73 If needed, submit actual data files with your report.  Small data files
  74 are preferred.  Big files may sometimes be necessary, but do not send them
  75 to the report address; rather take special arrangement with the maintainer.
  76
  77 Your feedback will help us to make a better and more portable package.
  78 Consider documentation errors as bugs, and report them as such.  If you
  79 develop anything pertaining to `tar' or have suggestions, let us know
  80 and share your findings by writing to <bug-tar@gnu.org>.
  81
  82
  83 Installation hints
  84 ------------------
  85
  86 Here are a few hints which might help installing `tar' on some systems.
  87
  88 * gzip and bzip2.
  89
  90 GNU tar uses the gzip and bzip2 programs to read and write compressed
  91 archives.  If you don't have these programs already, you need to
  92 install them.  Their sources can be found at:
  93
  94 ftp://ftp.gnu.org/gnu/gzip/
  95 http://sourceware.cygnus.com/bzip2/
  96
  97 If you see the following symptoms:
  98
  99    $ tar -xzf file.tar.gz
 100    gzip: stdin: decompression OK, trailing garbage ignored
 101    tar: Child returned status 2
 102
 103 then you have encountered a gzip incompatibility that should be fixed
 104 in gzip test version 1.3, which as of this writing is available at
 105 <ftp://alpha.gnu.org/gnu/gzip/>.  You can work around the
 106 incompatibility by using a shell command like
 107  `gzip -d <file.tar.gz | tar -xzf -'.
 108
 109 * Solaris issues.
 110
 111 GNU tar exercises many features that can cause problems with older GCC
 112 versions.  In particular, GCC 2.8.1 (sparc, -O1 or -O2) is known to
 113 miscompile GNU tar.  No compiler-related problems have been reported
 114 when using GCC 2.95.2 or later.
 115
 116 Recent versions of Solaris tar sport a new -E option to generate
 117 extended headers in an undocumented format.  GNU tar does not
 118 understand these headers.
 119
 120 * Static linking.
 121
 122 Some platform will, by default, prepare a smaller `tar' executable
 123 which depends on shared libraries.  Since GNU `tar' may be used for
 124 system-level backups and disaster recovery, installers might prefer to
 125 force static linking, making a bigger `tar' executable maybe, but able to
 126 work standalone, in situations where shared libraries are not available.
 127 The way to achieve static linking varies between systems.  Set LDFLAGS
 128 to a value from the table below, before configuration (see `INSTALL').
 129
 130         Platform        Compiler        LDFLAGS
 131
 132         (any)           Gnu C           -static
 133         AIX             (vendor)        -bnso -bI:/lib/syscalls.exp
 134         HPUX            (vendor)        -Wl,-a,archive
 135         IRIX            (vendor)        -non_shared
 136         OSF             (vendor)        -non_shared
 137         SCO 3.2v5       (vendor)        -dn
 138         Solaris         (vendor)        -Bstatic
 139         SunOS           (vendor)        -Bstatic
 140
 141 * Failed tests `ignfail.sh' or `incremen.sh'.
 142
 143 In an NFS environment, lack of synchronization between machine clocks
 144 might create difficulties to any tool comparing dates and file time stamps,
 145 like `tar' in incremental dumps.  This has been a recurrent problem with
 146 GNU Make for the last few years.  We would like a general solution.
 147
 148 * BSD compatibility matters.
 149
 150 Set LIBS to `-lbsd' before configuration (see `INSTALL') if the linker
 151 complains about `bsd_ioctl' (Slackware).  Also set CPPFLAGS to
 152 `-I/usr/include/bsd' if <sgtty.h> is not found (Slackware).
 153
 154 * OPENStep 4.2 swap files
 155
 156 Tar cannot read the file /private/vm/swapfile.front (even as root).
 157 This file is not a real file, but some kind of uncompressed view of
 158 the real compressed swap file; there is no reason to back it up, so
 159 the simplest workaround is to avoid tarring this file.
 160
 161
 162 Special topics
 163 --------------
 164
 165 Here are a few special matters about GNU `tar', not related to build
 166 matters.  See previous section for such.
 167
 168 * File attributes.
 169
 170 About *security*, it is probable that future releases of `tar' will have
 171 some behavior changed.  There are many pending suggestions to choose from.
 172 Today, extracting an archive not being `root', `tar' will restore suid/sgid
 173 bits on files but owned by the extracting user.  `root' automatically gets
 174 a lot of special privileges, `-p' might later become required to get them.
 175
 176 GNU `tar' does not properly restore symlink attributes.  Various systems
 177 implement flavors of symbolic links showing different behavior and
 178 properties.  We did not successfully sorted all these out yet.  Currently,
 179 the `lchown' call will be used if available, but that's all.
 180
 181 * POSIX compliance.
 182
 183 GNU `tar' implements an early draft of the POSIX 1003.1 `ustar' standard
 184 which is different from the final standard.  This will be progressively
 185 corrected over the incoming few years.  Don't be mislead by the mere
 186 existence of the --posix option.  Later releases will become able to
 187 read truly POSIX archives, and also to produce them under option.  (Also,
 188 if you look at the internals, don't take the GNU extensions you see for
 189 granted, as they are planned to change.)  GNU tar 2.0 will produce POSIX
 190 archives by default, but there is a long way before we get there.
 191
 192 * What's next?
 193
 194 In the future we will try to release tar-1.14 as soon as possible and
 195 start merging with paxutils afterwards.  We'll also try to rewrite
 196 some parts of the documentation after paxutils has been merged.