SysIII/usr/src/man/man1/tar.1

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.TH TAR 1
.SH NAME
tar \- tape file archiver
.SH SYNOPSIS
.B tar
[ key ] [ files ]
.SH DESCRIPTION
.I Tar\^
saves and restores files
on magnetic tape.
Its actions are controlled by the
.I key\^
argument.
The
.I key\^
is a string of characters containing
at most one function letter and possibly
one or more function modifiers.
Other arguments to the command are
.I files\^
(or directory
names)
specifying which files are to be dumped or restored.
In all cases, appearance of a directory name refers to
the files and (recursively) subdirectories of that directory.
.PP
The function portion of
the key is specified by one of the following letters:
.PP
.PD 0
.TP 8
.B r
The named
.I files\^
are written
on the end of the tape.
The
.B c
function implies this function.
.TP
.B x
The named
.I files\^
are extracted from the tape.
If a named file matches a directory whose contents
had been written onto the tape, this directory is (recursively) extracted.
The owner, modification time, and mode are restored (if possible).
If no
.I files\^
argument is given, the entire content of the
tape is extracted.
Note that if several files with the same name
are on the tape, the last one overwrites
all earlier ones.
.TP
.B t
The names of the specified files are listed each time that they occur
on the tape.
If no
.I files\^
argument is given,
all the names
on the tape are listed.
.TP
.B u
The named
.I files\^
are added to the tape if they
are not already there, or have
been modified since last written on that tape.
.TP
.B c
Create a new tape; writing begins at the beginning
of the tape, instead of after the last file.
This command implies
the
.B r
function.
.PD
.PP
The following characters may be used in addition to the letter
that selects the desired function:
.PP
.PD 0
.TP 8
.B 0,.\^.\^.\^,7
This
modifier selects the drive on which the tape is mounted.
The default is
.BR 1 .
.TP
.B v
Normally,
.I tar\^
does its work silently.
The
.B v
(verbose)
option causes it to type the name of each file it treats,
preceded by the function letter.
With the
.B t
function,
.B v
gives more information about the
tape entries than just the name.
.TP
.B w
causes
.I tar\^
to print the action to be taken, followed by the name of the file, and then
wait for the user's confirmation.
If a word beginning with
.B y
is given, the action is performed.
Any other input means
``no''.
.TP
.B f
causes
.I tar\^
to use the next argument as the name of the archive instead
of
.BR /dev/mt? .
If the name of the file is
.BR \- ,
.I tar\^
writes to the
standard output or reads from the standard input, whichever is
appropriate.
Thus,
.I tar\^
can be used as the head or tail of a pipeline.
.I Tar\^
can also be used to move hierarchies with the command:
.PD
.PP
.RS
.RS
cd \|fromdir; \|tar \|cf \|\- \|\f3.\fP \|\(bv \|(cd \|todir; \|tar \|xf \|\-)
.RE
.RE
.PP
.PD 0
.TP 8
.B b
causes
.I tar\^
to use the next argument as the blocking factor for tape
records.
The default is 1, the maximum is 20.
This option
should only be used with raw magnetic tape archives (see
.B f
above).
The block size is determined automatically when reading
tapes (key letters
.B x
and
.BR t ).
.TP
.B l
tells
.I tar\^
to complain if it cannot resolve all of the links
to the files being dumped.
If
.B l
is not specified, no
error messages are printed.
.TP
.B m
tells
.I tar\^
to not restore the modification times.
The modification time
of the file
will be the time of extraction.
.PD
.SH FILES
/dev/mt?
.br
/tmp/tar\(**
.SH DIAGNOSTICS
Complaints about bad key characters and tape read/write errors.
.br
Complaints if enough memory is not available to hold
the link tables.
.SH BUGS
There is no way to ask for the
.IR n -th
occurrence of a file.
.br
Tape errors are handled ungracefully.
.br
The
.B u
option can be slow.
.br
The
.B b
option should not be used with archives that are
going to be updated.
The current magnetic tape driver cannot
backspace raw magnetic tape.
If the archive is on a disk file, the
.B b
option should not be used at all, because updating
an archive stored on disk can destroy it.
.br
The current limit on file-name length is
100 characters.