@subsection Old Option Style
@cindex options, old style
@cindex old option style
+@cindex option syntax, traditional
-Like short options, @dfn{old options} are single letters. However, old options
+As far as we know, all @command{tar} programs, @acronym{GNU} and
+non-@acronym{GNU}, support @dfn{old options}: that is, if the first
+argument does not start with @samp{-}, it is assumed to specify option
+letters. @GNUTAR{} supports old options not only for historical
+reasons, but also because many people are used to them. If the first
+argument does not start with a dash, you are announcing the old option
+style instead of the short option style; old options are decoded
+differently.
+
+Like short options, old options are single letters. However, old options
must be written together as a single clumped set, without spaces separating
-them or dashes preceding them@footnote{Beware that if you precede options
-with a dash, you are announcing the short option style instead of the
-old option style; short options are decoded differently.}. This set
+them or dashes preceding them. This set
of letters must be the first to appear on the command line, after the
@command{tar} program name and some white space; old options cannot appear
anywhere else. The letter of an old option is exactly the same letter as
Here, @samp{20} is the argument of @option{-b} and @samp{/dev/rmt0} is
the argument of @option{-f}.
-On the other hand, this old style syntax makes it difficult to match
+The old style syntax can make it difficult to match
option letters with their corresponding arguments, and is often
confusing. In the command @w{@samp{tar cvbf 20 /dev/rmt0}}, for example,
@samp{20} is the argument for @option{-b}, @samp{/dev/rmt0} is the
second example, however, uses @file{z} as the value for option
@samp{f} --- probably not what was intended.
-Old options are kept for compatibility with old versions of @command{tar}.
-
This second example could be corrected in many ways, among which the
following are equivalent:
@kbd{tar cf archive.tar.gz -z file}
@end smallexample
-@cindex option syntax, traditional
-As far as we know, all @command{tar} programs, @acronym{GNU} and
-non-@acronym{GNU}, support old options. @GNUTAR{}
-supports them not only for historical reasons, but also because many
-people are used to them. For compatibility with Unix @command{tar},
-the first argument is always treated as containing command and option
-letters even if it doesn't start with @samp{-}. Thus, @samp{tar c} is
-equivalent to @w{@samp{tar -c}:} both of them specify the
-@option{--create} (@option{-c}) command to create an archive.
-
@node Mixing
@subsection Mixing Option Styles
@item --group=@var{group}
Files added to the @command{tar} archive will have a group @acronym{ID} of @var{group},
-rather than the group from the source file. @var{group} is first decoded
-as a group symbolic name, but if this interpretation fails, it has to be
-a decimal numeric group @acronym{ID}. @xref{override}.
+rather than the group from the source file. @var{group} can specify a
+symbolic name, or a numeric @acronym{ID}, or both as
+@var{name}:@var{id}. @xref{override}.
Also see the comments for the @option{--owner=@var{user}} option.
Specifies that @command{tar} should use @var{user} as the owner of members
when creating archives, instead of the user associated with the source
-file. @var{user} is first decoded as a user symbolic name, but if
-this interpretation fails, it has to be a decimal numeric user @acronym{ID}.
+file. @var{user} can specify a symbolic name, or a numeric
+@acronym{ID}, or both as @var{name}:@var{id}.
@xref{override}.
This option does not affect extraction from archives.
Verbose output appears on the standard output except when an archive is
being written to the standard output, as with @samp{tar --create
---file=- --verbose} (@samp{tar cfv -}, or even @samp{tar cv}---if the
+--file=- --verbose} (@samp{tar cvf -}, or even @samp{tar cv}---if the
installer let standard output be the default archive). In that case
@command{tar} writes verbose output to the standard error stream.
@smallexample
@kbd{tar --create --file=empty-archive.tar --files-from=/dev/null}
-@kbd{tar cfT empty-archive.tar /dev/null}
+@kbd{tar -cf empty-archive.tar -T /dev/null}
@end smallexample
@xopindex{extract, complementary notes}
Specifies that @command{tar} should use @var{user} as the owner of members
when creating archives, instead of the user associated with the source
-file. The argument @var{user} can be either an existing user symbolic
-name, or a decimal numeric user @acronym{ID}.
+file.
+
+If @var{user} contains a colon, it is taken to be of the form
+@var{name}:@var{id} where a nonempty @var{name} specifies the user
+name and a nonempty @var{id} specifies the decimal numeric user
+@acronym{ID}. If @var{user} does not contain a colon, it is taken to
+be a user number if it is one or more decimal digits; otherwise it is
+taken to be a user name.
+
+If a name is given but no number, the number is inferred from the
+current host's user database if possible, and the file's user number
+is used otherwise. If a number is given but no name, the name is
+inferred from the number if possible, and an empty name is used
+otherwise. If both name and number are given, the user database is
+not consulted, and the name and number need not be valid on the
+current host.
There is no value indicating a missing number, and @samp{0} usually means
@code{root}. Some people like to force @samp{0} as the value to offer in
@opindex group
Files added to the @command{tar} archive will have a group @acronym{ID} of @var{group},
-rather than the group from the source file. The argument @var{group}
-can be either an existing group symbolic name, or a decimal numeric group @acronym{ID}.
+rather than the group from the source file. As with @option{--owner},
+the argument @var{group} can be an existing group symbolic name, or a
+decimal numeric group @acronym{ID}, or @var{name}:@var{id}.
@end table
@node Ignore Failed Read
For example:
@smallexample
-$ @kbd{tar cfz archive.tar.gz .}
+$ @kbd{tar czf archive.tar.gz .}
@end smallexample
You can also let @GNUTAR{} select the compression program based on
compression:
@smallexample
-$ @kbd{tar cfa archive.tar.bz2 .}
+$ @kbd{tar caf archive.tar.bz2 .}
@end smallexample
@noindent
whereas the following one will use @command{lzma}:
@smallexample
-$ @kbd{tar cfa archive.tar.lzma .}
+$ @kbd{tar caf archive.tar.lzma .}
@end smallexample
For a complete list of file name suffixes recognized by @GNUTAR{},
invocation of @GNUTAR{}:
@smallexample
-$ @kbd{cat archive.tar.gz | tar tfz -}
+$ @kbd{cat archive.tar.gz | tar tzf -}
@end smallexample
Notice also, that there are several restrictions on operations on
use @env{GZIP} as in the example below:
@smallexample
-$ @kbd{GZIP=--best tar cfz archive.tar.gz subdir}
+$ @kbd{GZIP=--best tar czf archive.tar.gz subdir}
@end smallexample
@noindent
the following:
@smallexample
-$ tar cfvv ../archive.tar .
+$ tar cvvf ../archive.tar .
drwxr-xr-x gray/staff 0 2007-10-30 15:13 ./
-rw-r--r-- gray/staff 4 2007-10-30 15:11 ./jeden
hrw-r--r-- gray/staff 0 2007-10-30 15:11 ./one link to ./jeden
@smallexample
$ @kbd{tar --create --multi-volume --file=/dev/tape0 --file=/dev/tape1 @var{files}}
-$ @kbd{tar cMff /dev/tape0 /dev/tape1 @var{files}}
+$ @kbd{tar -cM -f /dev/tape0 -f /dev/tape1 @var{files}}
@end smallexample
The second method is to use the @samp{n} response to the tape-change
@smallexample
@group
-$ @kbd{tar cfMV /dev/tape "Daily backup for `date +%Y-%m-%d`"}
+$ @kbd{tar -cM -f /dev/tape -V "Daily backup for `date +%Y-%m-%d`"}
$ @kbd{tar --create --file=/dev/tape --multi-volume \
--label="Daily backup for `date +%Y-%m-%d`"}
@end group
projects / chaz / tar / blobdiff