Being careful, the first thing is really checking that you are using
GNU tar, indeed. The --version option
causes tar to print information about its name, version,
origin and legal status, all on standard output, and then exit
successfully. For example, ‘tar --version’ might print:
tar (GNU tar) 1.15.2
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software. You may redistribute copies of it under the terms of
the GNU General Public License <https://www.gnu.org/licenses/gpl.html>.
There is NO WARRANTY, to the extent permitted by law.
Written by John Gilmore and Jay Fenlason.
The first occurrence of ‘tar’ in the result above is the program
name in the package (for example, rmt is another program),
while the second occurrence of ‘tar’ is the name of the package
itself, containing possibly many programs. The package is currently
named ‘tar’, after the name of the main program it
Another thing you might want to do is checking the spelling or meaning
of some particular tar option, without resorting to this
manual, for once you have carefully read it. GNU tar
has a short help feature, triggerable through the
--help option. By using this option, tar will
print a usage message listing all available options on standard
output, then exit successfully, without doing anything else and
ignoring all other options. Even if this is only a brief summary, it
may be several screens long. So, if you are not using some kind of
scrollable window, you might prefer to use something like:
$ tar --help | less
presuming, here, that you like using less for a pager. Other
popular pagers are more and pg. If you know about some
keyword which interests you and do not want to read all the
--help output, another common idiom is doing:
tar --help | grep keyword
for getting only the pertinent lines. Notice, however, that some
tar options have long description lines and the above
command will list only the first of them.
The exact look of the option summary displayed by tar --help is
configurable. See Configuring Help Summary, for a detailed description.
If you only wish to check the spelling of an option, running tar
--usage may be a better choice. This will display a terse list of
tar option without accompanying explanations.
The short help output is quite succinct, and you might have to get
back to the full documentation for precise points. If you are reading
this paragraph, you already have the tar manual in some
form. This manual is available in a variety of forms from
https://www.gnu.org/software/tar/manual. It may printed out of the GNU tar
distribution, provided you have TeX already installed somewhere,
and a laser printer around. Just configure the distribution, execute
the command ‘make dvi’, then print doc/tar.dvi the
usual way (contact your local guru to know how). If GNU tar
has been conveniently installed at your place, this
manual is also available in interactive, hypertextual form as an Info
file. Just call ‘info tar’ or, if you do not have the
info program handy, use the Info reader provided within
GNU Emacs, calling ‘tar’ from the main Info menu.
There is currently no man page for GNU tar.
If you observe such a man page on the system you are running,
either it does not belong to GNU tar, or it has not
been produced by GNU. Some package maintainers convert
tar --help output to a man page, using help2man. In
any case, please bear in mind that the authoritative source of
information about GNU tar is this Texinfo documentation.
 There are plans to merge the cpio and
tar packages into a single one which would be called
paxutils. So, who knows if, one of this days, the
--version would not output ‘tar (GNU paxutils) 3.2’
Published under the terms of the GNU General Public License