mdtar(1) General Commands Manual mdtar(1)
mdtar - multivolume archiver
mdtar [key] [name...]
The command saves multiple files on multiple archives (usually an RX50 diskette, but any file/device may be specified). actions are con-
trolled by the key argument. The key is a string of characters containing one function letter and one or more function modifiers. Other
arguments to 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. also saves special files.
-C Changes directory to specified 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 and from one might use
mdtar c -C /usr include . -C /etc .
The function portion of the key is specified by a letter.
c Creates a new archive. Writing begins at the beginning of the archive instead of after the last file.
r Writes the named files to the end of the archive.
t Generates archive table of contents. If no argument is given, all of the names on the archive are listed.
u 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.
x 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 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.
The following characters may be used to qualify the function desired in addition to one or more of the above letters.
0...9 Selects unit number of the drive as an alternate disk drive. The default disk drive is the device named
A Uses the specified number (next argument) as archive with which to begin the output. This switch is intended for error recovery.
outputs files in terms of Archives. Each Archive contains a number of files. If 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 at the nth Archive. You must issue the same path (set of files) as in the first command. This will guarantee that will
begin at the correct file on Archive n. If the v mode is specified, outputs informational messages to inform the user of
progress. For example, the following command will dump the entire directory structure:
If an error occurs on Archive 7, to restart at the 7th Archive, without having to re-dump the first 6 Archives, issue the follow-
mdtar cvA 7
will tell you it is skipping the first 6 Archives and will resume output with the data that begins Archive 7.
b Uses the specified number (next argument) as the blocking factor. The default is 20 (the maximum is 20).
B Forces output blocking to 20 blocks per record.
f Uses the specified file (next argument) as the name of the archive. If the name of the file is -, writes to standard output
F[fR] Operates in fast mode. When F is specified, skips all SCCS directories, core files, and errs files. When FF is specified, also
skips all a.out and *.o files.
h Saves a copy of the file (excludes symbolic links). The default action of is to place symbolic link information on the output
device. A copy of the file IS NOT saved on the output device.
i Ignores checksum errors found in the archive.
l Displays an error message if all links to the files dumped cannot be resolved. If -l is not specified, no error messages are
m Does not restore file modification times. The modification time is the time of extraction. Normally, restores modification
times of regular and special files.
o Suppresses the normal directory information. On output, normally places information specifying owner and modes of directories in
the archive. Former versions of when encountering this information will give the error message
<name>/: cannot create.
p Restores the named files to their original modes, ignoring the present Setuid and sticky information will also be restored to the
super-user. You must be Superuser to perform this option. For further information, see S_ISVTX.
s Uses specified number (next argument) as size of media in 512-byte blocks. This enables to be used with devices of different
physical media sizes. The default is 800 blocks (assumption is an RX50 output Archive).
v Displays detailed (verbose) information as it archives files. Normally does its work silently. With the t function, the verbose
option gives more information about the archive entries than just their names.
#mdtar cvf mdtar-out vmunix
Produces the output ``a vmunix 1490 blocks'' where 1490 is the number of 512 byte blocks in the file ``vmunix''.
#mdtar xvf mdtar-out
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.
w 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.
The u option can be slow.
The current limit on file name length is 100 characters.
There is no way to follow symbolic links selectively.
Indicates bad key characters and archive read/write errors.
Indicates if enough memory is not available to hold the link tables.