(tar)Archive Reading Options

File Writing Options

Extracting Archive Members

Extracting Archive Members

Options to Help Read Archives
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     *(This message will disappear, once this node revised.)*

FIXME: each option wants its own node.  summary after menu

   Normally, `tar' will request data in full block increments from an
archive storage device.  If the device cannot return a full block,
`tar' will report an error.  However, some devices do not always return
full blocks, or do not require the last block of an archive to be
padded out to the next block boundary.  To keep reading until you
obtain a full block, or to accept an incomplete block if it contains an
end-of-archive marker, specify the `--read-full-blocks' (`-B') option
in conjunction with the `--extract' (`-x') or `--list' (`-t')
operations.

FIXME: xref Listing Contents
   .

   The `--read-full-blocks' (`-B') option is turned on by default when
`tar' reads an archive from standard input, or from a remote machine.
This is because on BSD Unix systems, attempting to read a pipe returns
however much happens to be in the pipe, even if it is less than was
requested.  If this option were not enabled, `tar' would fail as soon
as it read an incomplete block from the pipe.

   If you're not sure of the blocking factor of an archive, you can
read the archive by specifying `--read-full-blocks' (`-B') and
`--block-size=512-SIZE' (`-b 512-SIZE'), using a blocking factor larger
than what the archive uses.  This lets you avoid having to determine
the blocking factor of an archive.
FIXME: xref Blocking Factor
   .

`--read-full-blocks'
`-B'
     Use in conjunction with `--extract' (`-x') to read an archive which
     contains incomplete blocks, or one which has a blocking factor less
     than the one specified.

   Normally `tar' stops reading when it encounters a block of zeros
between file entries (which usually indicates the end of the archive).
`--ignore-zeros' (`-i') allows `tar' to completely read an archive
which contains a block of zeros before the end (i.e. a damaged archive,
or one which was created by `cat'-ing several archives together).

   The `--ignore-zeros' (`-i') option is turned off by default because
many versions of `tar' write garbage after the end-of-archive entry,
since that part of the media is never supposed to be read.  GNU `tar'
does not write after the end of an archive, but seeks to maintain
compatablity among archiving utilities.

`--ignore-zeros'
`-i'
     To ignore blocks of zeros (ie. end-of-archive entries) which may be
     encountered while reading an archive.  Use in conjunction with
     `--extract' (`-x') or `--list' (`-t').

   If you are using a machine with a small amount of memory, and you
need to process large list of file names, you can reduce the amount of
space `tar' needs to process the list.  To do so, specify the
`--same-order' (`-s') option and provide an ordered list of file names.
This option tells `tar' that the NAME arguments provided on the command
line, or read from a file using the `--files-from=FILE-OF-NAMES' (`-T
FILE-OF-NAMES') option, are listed in the same order as the files in
the archive.

   You can create a file containing an ordered list of files in the
archive by storing the output produced by `tar --list
--file=ARCHIVE-NAME'.
FIXME: xref Listing Contents
   , for information on the `--list' (`-t') operation.

   This option is probably never needed on modern computer systems.

`--same-order'
`--preserve-order'
`-s'
     To process large lists of file names on machines with small
     amounts of memory.  Use in conjunction with `--compare' (`-d'),
     `--list' (`-t') or `--extract' (`-x').

FIXME: we don't need/want --preserve to exist any more