Options to GNU tar can be given in three different styles. In traditional style, the first argument is a cluster of option letters and all subsequent arguments supply arguments to those options that require them. The arguments are read in the same order as the option letters. Any command line words that remain after all options have been processed are treated as non-option arguments: file or archive member names.
For example, the c option requires creating the archive, the v option requests the verbose operation, and the f option takes an argument that sets the name of the archive to operate upon. The following command, written in the traditional style, instructs tar to store all files from the directory /etc into the archive file etc.tar, verbosely listing the files being archived:
tar cfv etc.tar /etc
In UNIX or short-option style, each option letter is prefixed with a single dash, as in other command line utilities. If an option takes an argument, the argument follows it, either as a separate command line word, or immediately following the option. However, if the option takes an optional argument, the argument must follow the option letter without any intervening whitespace, as in -g/tmp/snar.db.
Any number of options not taking arguments can be clustered together after a single dash, e.g. -vkp. An option that takes an argument (whether mandatory or optional) can appear at the end of such a cluster, e.g. -vkpf a.tar.
The example command above written in the short-option style could look like:
tar -cvf etc.tar /etc
or tar -c -v -f etc.tar /etc
In GNU or long-option style, each option begins with two dashes and has a meaningful name, consisting of lower-case letters and dashes. When used, the long option can be abbreviated to its initial letters, provided that this does not create ambiguity. Arguments to long options are supplied either as a separate command line word, immediately following the option, or separated from the option by an equals sign with no intervening whitespace. Optional arguments must always use the latter method.
Here are several ways of writing the example command in this style:
tar --create --file etc.tar --verbose /etc
or (abbreviating some options): tar --cre --file=etc.tar --verb /etc
The options in all three styles can be intermixed, although doing so with old options is not encouraged.