mdtar.1

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 1 代码 · 共 234 行

.\" SCCSID: @(#)mdtar.1	2.6	7/17/87
.TH mdtar 1
.SH Name
mdtar \- multivolume archiver
.SH Syntax
.B mdtar
[\|\fIkey\fR\|] [\|\fIname...\fR\|]
.SH Description
.NXR "mdtar command"
.NXR "file" "backing up multiple"
.NXA "mdtar command" "tar command"
The
.PN mdtar 
command saves multiple files on  multiple archives (usually an  RX50
diskette, but any file/device may be specified).  
.PN mdtar 
actions are controlled by the
.B key
argument.  The
.B key
is a string of characters containing one function letter and 
one or more function modifiers.  Other arguments to 
.PN mdtar
are file or directory names specifying which files to dump or restore.
In all cases, appearance of a directory name refers to
the files and, recursively, subdirectories of that directory. 
.PN mdtar
also saves special files.
.SH Options
.IP \fB\-C\fR 10
Changes directory to specified
.IR name .  
This allows multiple directories not
related by a close common parent, to be archived using short
relative path names.  For example, to archive files from 
.PN /usr/include
and from 
.PN /etc ,
one might use
.EX
mdtar c \-C /usr include . \-C /etc .
.EE
.PP
The function portion of the key is specified by a letter.
.NXR "mdtar command" "key list"
.IP \fBc\fR 10
Creates a new archive.  Writing begins at 
the beginning of the archive
instead of after the last file.  
.IP \fBr\fR 
Writes the named files to the end of the archive.
.IP \fBt\fR 
Generates archive table of contents.  If no argument is given, all  
of the names on the archive
are listed.
.IP \fBu\fR 
Updates the current archive.  Adds the named files to the archive, if 
they are not there already or if they have been modified 
since last put on the archive.
.IP \fBx\fR 
Extracts each specified file from the archive.  If the named file
matches a directory whose contents had
been written onto the archive, this
directory is recursively extracted.
The owner, modification time, and mode
are restored if you are the superuser and if you have
also specified the 
.B p
switch.  If no file argument is given, the entire content
of the archive is extracted.  
If multiple entries specifying the same
file are on the archive, the last one overwrites previous versions. 
.PP
.sp
The following characters may be
used to qualify the function desired
in addition to one or more of the above letters.
.NXR "mdtar command" "function modifiers"
.IP \fB0...9\fR 10
Selects unit number of the drive as an alternate disk drive. 
The default disk drive is the device named 
.PN /dev/rra1a .
.IP \fBA\fR 
Uses the specified number (next argument) as archive with which to begin
the output.  
This switch
is intended for error recovery. 
.PN mdtar 
outputs files in terms of Archives.
Each Archive contains a number of files. If 
.PN mdtar 
has been requested to dump
a path (set of files)
that consist of (for example) 10 archives and there is
an error writing the nth Archive,
then the A modifier may be used to restart
.PN mdtar
at the nth Archive. 
.NT CAUTION
You must issue the same
path (set of files) as in the first command. This will guarantee that 
.PN mdtar
will begin at the correct file on Archive n. 
.NE
If the v mode is specified, 
.PN mdtar 
outputs informational
messages to inform the 
user of progress.
For example, the following command will dump 
the entire directory structure:
.EX
mdtar cv \*   
.EE
If an error occurs on Archive 7, 
to restart at the 7th Archive, without having to
re-dump the first 6 Archives, issue the following command:
.EX
mdtar cvA 7 \*
.EE
.PN mdtar 
will tell you it is skipping the first 6 Archives and will resume
output with the data that begins Archive 7.
.IP \fBb\fR 10
Uses the specified number (next argument) as the blocking factor.  
The default is 20 (the maximum is 20).
.IP \fBB\fR 
Forces output blocking to 20 blocks per record. 
.IP \fBf\fR 
Uses the specified file (next argument) as the name of the archive.  
If the name of the file is \-, 
.PN mdtar
writes to
standard output (piping).
.IP \fBF\fR[\fB\F\fR] 
Operates in fast mode.
When
.B F
is specified,
.PN mdtar
skips all SCCS directories, core files, and errs files.
When
.B FF
is specified,
.PN mdtar
also skips all a.out and *.o files.
.IP \fBh\fR 
Saves a copy of the file (excludes symbolic links).  
The default action of 
.PN mdtar
is to place symbolic link
information on the output device. A copy of the file IS NOT
saved on the output device. 
.IP \fBi\fR 
Ignores checksum errors found in the archive.
.IP \fBl\fR 
Displays an error message if all links to the
files dumped cannot be resolved. If \-l is not specified, no error
messages are printed.
.IP \fBm\fR 
Does not restore file modification times.  The modification time
is the time of extraction.  Normally, 
.PN mdtar
restores modification times of regular and special files.
.IP \fBo\fR 
Suppresses the normal directory information.  On output,
.PN mdtar
normally places information specifying owner and modes of directories
in the archive.  Former versions of
.PN mdtar ,
when encountering this information will give the error message
.EX
<name>/: cannot create.
.EE
.IP \fBp
Restores the named files to their original modes,
ignoring the present
.MS umask 2 .
Setuid and sticky information
will also be restored to the super-user.
You must be Superuser to perform this option.
For further information, see 
.MS stat 2 ,
S_ISVTX.
.IP \fBs\fR 
Uses specified number (next argument) as size of media in 512-byte 
blocks.  This enables 
.PN mdtar 
to be used with devices of different physical media
sizes. The default is 800 blocks (assumption is an RX50 output Archive).
.IP \fBv\fR 
Displays detailed (verbose) information as it archives files.  
Normally
.PN mdtar 
does its work silently.
With the
.B t
function, the verbose option
gives more information about the archive entries than just their names.
.EX 
#cd
#mdtar cvf mdtar-out vmunix
.EE
Produces the output ``a vmunix 1490 blocks''
where 1490 is the number of 512 byte blocks in the file ``vmunix''.
.EX 
#mdtar xvf mdtar-out
.EE
Produces the output ``x vmunix, 762880 bytes, 1490 blocks'' where 762880 is the
number of bytes and 1490 is the number of 512 byte
blocks in the file ``vmunix'' which was extracted.
.IP \fBw\fR 
Displays action to be taken for each file and prompts for confirmation.  
If a word beginning with `y'
is given, the action is done. Any other input means do not do it.
.SH Restrictions
.NXR "mdtar command" "restricted"
The 
.B u
option can be slow.
.PP
The current limit on file name length is 100 characters.
.PP
There is no way to follow symbolic links selectively.
.SH Diagnostics
.NXR "mdtar command" "diagnostics"
Indicates bad key characters and archive read/write errors.
.PP
Indicates if enough memory is not available to hold the link tables.
.SH Files
.PN /tmp/tar*
.SH See Also
stat(2), tar(1)