README for GNU tar See the end of file for copying conditions. * Introduction 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, time stamps 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 'COPYING' for copying conditions. See file 'INSTALL' for compilation and installation instructions. 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', an extra option may be accepted after './configure': * Install ** Selecting the default archive format. The default archive format is GNU, this can be overridden by presetting DEFAULT_ARCHIVE_FORMAT while configuring. The allowed values are GNU, V7, OLDGNU, USTAR and POSIX. ** Selecting the default archive device 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. ** Selecting full pathname of the "rmt" binary. Previous versions of tar always looked for "rmt" binary in the directory "/etc/rmt". However, the "rmt" program included in the distribution was installed under "$prefix/libexec/rmt". To fix this discrepancy, tar now looks for "$prefix/libexec/rmt". If you do not want this behavior, specify full path name of "rmt" binary using DEFAULT_RMT_DIR variable, e.g.: ./configure DEFAULT_RMT_DIR=/etc If you already have a copy of "rmt" installed and wish to use it instead of the version supplied with the distribution, use --with-rmt option: ./configure --with-rmt=/etc/rmt This will also disable building the included version of rmt. ** Installing backup scripts. This version of tar is shipped with the shell scripts for producing incremental backups (dumps) and restoring filesystems from them. The name of the backup script is "backup". The name of the restore script is "restore". They are installed in "$prefix/sbin" directory. Use option --enable-backup-scripts to compile and install these scripts. ** '--disable-largefile' omits support for large files, even if the operating system supports large files. Typically, large files are those larger than 2 GB on a 32-bit host. * Installation hints Here are a few hints which might help installing 'tar' on some systems. ** gzip and bzip2. GNU tar uses the gzip and bzip2 programs to read and write compressed archives. If you don't have these programs already, you need to install them. Their sources can be found at: ftp://ftp.gnu.org/gnu/gzip/ http://sourceware.cygnus.com/bzip2/ If you see the following symptoms: $ tar -xzf file.tar.gz gzip: stdin: decompression OK, trailing garbage ignored tar: Child returned status 2 then you have encountered a gzip incompatibility that should be fixed in gzip test version 1.3, which as of this writing is available at <ftp://alpha.gnu.org/gnu/gzip/>. You can work around the incompatibility by using a shell command like 'gzip -d <file.tar.gz | tar -xzf -'. ** Solaris issues. GNU tar exercises many features that can cause problems with older GCC versions. In particular, GCC 2.8.1 (sparc, -O1 or -O2) is known to miscompile GNU tar. No compiler-related problems have been reported when using GCC 2.95.2 or later. Recent versions of Solaris tar sport a new -E option to generate extended headers in an undocumented format. GNU tar does not understand these headers. ** 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 tests 'ignfail.sh' or 'incremen.sh'. In an NFS environment, lack of synchronization between machine clocks might create difficulties to any tool comparing dates and file time stamps, like 'tar' in incremental dumps. This has been a recurrent problem with GNU Make 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 'bsd_ioctl' (Slackware). Also set CPPFLAGS to '-I/usr/include/bsd' if <sgtty.h> is not found (Slackware). ** OPENStep 4.2 swap files Tar cannot read the file /private/vm/swapfile.front (even as root). This file is not a real file, but some kind of uncompressed view of the real compressed swap file; there is no reason to back it up, so the simplest workaround is to avoid tarring this file. * 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 behavior 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 privileges, '-p' might later become required to get them. GNU 'tar' does not properly restore symlink attributes. Various systems implement flavors of symbolic links showing different behavior 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' is able to create archive in the following formats: *** The format of UNIX version 7 *** POSIX.1-1988 format, also known as "ustar format" *** POSIX.1-2001 format, also known as "pax format" *** Old GNU format (described below) In addition to those, GNU 'tar' is also able to read archives produced by 'star' archiver. A so called 'Old GNU' format is based on an early draft of the POSIX 1003.1 'ustar' standard which is different from the final standard. It defines its extensions (such as incremental backups and handling of the long file names) in a way incompatible with any existing tar archive format, therefore the use of old GNU format is strongly discouraged. Please read the file NEWS for more information about POSIX compliance and new 'tar' features. * What's next? GNU tar will be merged into GNU paxutils: a project containing several utilities related to creating and handling archives in various formats. The project will include tar, cpio and pax utilities. * Bug reporting. Send bug reports to <bug-tar@gnu.org>. A bug report should contain 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 to <bug-tar@gnu.org>. * Copying Copyright 1990-2023 Free Software Foundation, Inc. This file is part of GNU tar. GNU tar is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. GNU tar is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. NOTE ON COPYRIGHT YEARS In copyright notices where the copyright holder is the Free Software Foundation, then where a range of years appears, this is an inclusive range that applies to every year in the range. For example: 2005-2008 represents the years 2005, 2006, 2007, and 2008. Local Variables: mode: outline paragraph-separate: "[ ]*$" version-control: never End:
