10.0;rwmt (read_write_magtape), revision 1.0, 88/03/04
rwmt (read_write_magtape) - read/write foreign magtapes.
usage: rwmt [option]... [-p] {-r|-w|-i|-l} [pathname]...
DESCRIPTION
rwmt reads tapes from non-Domain installations and writes tapes that can
be read by non-Domain installations. rwmt can read and write unlabeled
tapes, as well as ANSI level 1-4 labeled tapes.
pathname (optional)
Specify the name of file to be read from or written to
tape. This argument is valid only with the -r and -w
mode-control options (below). Multiple pathnames are
permitted. Wildcarding is permitted for write (-w)
operations only.
Default if omitted: read pathnames from standard input
OPTIONS
Mode control
You must specify one of the following mode-control options. If you omit
this option, rwmt prompts you for it. The -p option tells rwmt to prompt
for all necessary options.
-l[abel] Write ANSI X3.27-1978 volume label on a tape. This option
causes rwmt to write an ANSI volume label and dummy file
on the magtape volume. You may specify an optional owner
and volume ID, which are stored in the volume label. (see
-vid and -own below. This is the way to initialize a
labeled tape; if any information existed on the tape, it
is erased by this labeling operation.
If you are labeling a tape, you can also use the following
two options.
-vid vol_id Specify a 1-6 character volume ID for use
when labeling a volume. This option is valid
only when used with the -l mode-control
option (above). The default volume ID is ' '
(blank).
-own owner_id
Specify a 1-14 character owner ID for use
when labeling a volume. This option is valid
only when used with the -l mode-control
option (above). The default owner ID is ' '
(blank).
-i[ndex] List objects on an ANSI-labeled physical tape volume.
-index produces a listing of all files or file sections on
an ANSI-labeled physical tape volume. The contents of the
physical volume (VOL1) label and all file header labels
are written to standard output.
-w[rite] Specify one or more disk files (pathname argument) to be
written to tape. The default format is ANSI labeled,
ASCII, fixed-length records of 80 bytes each, and 80-byte
blocks. If desired, any of these parameters can be
changed using the options described below. If more than
one pathname is specified, the disk files are written to
sequential tape files. Tapes written by rwmt are always
in accordance with ANSI level 4 format.
Before writing a labeled file, the tape volume itself must
be labeled with the -label mode-control option (above).
-r[ead] Specify one or more tape files to be read from tape and
stored on disk. read reads one or more tape files and
writes them to disk using the specified pathnames
(pathname argument). The default tape file format is the
same as that for the write option. If the tape is labeled
under ANSI level 2, 3, or 4, the file format (block
length, record length, and record format) is read from the
tape. If the tape is unlabeled, or labeled with ANSI
level 1, you must specify the tape format using the
options below. If more than one pathname is specified,
adjacent tape files are read and stored under the
specified pathnames.
Label Control
-ansi (default)
Specify that the tape is labeled in conformance to ANSI
X3.27-1978, level 1, 2, 3, or 4.
-unlab Specify that the tape is unlabeled. Data spanning physical
volumes is not supported on unlabeled tapes.
-asc (default) Specify that all tape file contents are in ASCII
characters.
-ebc Specify that all tape file contents (except labels) are in
EBCDIC characters.
-raw Specify that all tape file data is to be treated in raw
form.
-npar (default)
Specify no disturbance of parity bits when reading or
writing data.
-par Specify that parity bits should be forced off when reading
data from tape and forced on when writing data to tape.
-rl reclen Specify the maximum length, in bytes, of a record in the
tape file. This option is valid only when used with either
the -r or the -w mode-control options (above). It is
unnecessary when reading an ANSI level 2, 3, or 4 file.
The default record length is 80 bytes.
-bl blocklen Specify the length, in bytes, of a physical tape block.
This option is valid only when used with either the -r or
the -w mode-control options (above). It is unnecessary
when reading an ANSI level 2, 3, or 4 file. The default
block length is 80 bytes.
-bf blockfac Specify a blocking factor -- the number of records to
store into or read from a physical tape block. This is an
alternative to the -bl option, since the record length
multiplied by the blocking factor yields the block length.
This option is valid only when used with either the -r or
-w mode-control options (above). Using this option is
meaningful only if your tape has fixed-length records.
This option is unnecessary when reading an ANSI level 2,
3, or 4 file. The default blocking factor is 1.
-rf format Specify record format. Valid values for format are f
(fixed-length records and blocks); d (variable-length
records (this is ANSI 'D' format)); s (spanned records);
or u (undefined record format). The default format is f.
Note that if you are writing a cartridge tape, only 512
byte blocks may be written; d, s, and u formats are not
supported.
Tape File Identifiers
-fid file_id Specify a 1-17 character file ID to be written in the file
header label for use when writing a file to a labeled
volume. This option is valid only when used with the -w
mode-control option (above). If this option is omitted,
the name of the file being written is used.
-f [position] Specify the file position for -r or -w operations. Valid
values for position are cur, end, or a nonzero integer
value. A position of cur selects the current tape
position; the tape must have been previously read or
written by rwmt and its position must not have been
disturbed. This option is valid only when used with either
the -r or the -w mode-control options (above).
A position of end selects the end of the tape file set.
This option is valid only when used with the -w mode-
control option, and causes rwmt to append the specified
disk file (pathname argument) to the very end of the tape
file set.
A position specified by a nonzero integer value selects
the file at that absolute position in the tape volume.
This option is valid only when used with either the -r or
-w mode-control options (above). If multiple pathname
arguments are supplied, the value of position is
incremented by one after each file has been read or
written.
The default value for position is 1.
Backup Device Control
-dev d[unit] Specify device type and unit number. d must be either m
(for reel-to-reel magnetic tape), ct (for cartridge tape),
or f (for floppy), depending on which drive is being used.
unit is an integer (0-3). Both are required for
reel-to-reel tapes (that is, -dev m2). A unit number is
not required for floppy disks and cartridge tapes (that
is, -dev f). If this option is omitted, rbak assumes
device m0.
-nobs Specifies that byte swapping should not be done in
software. This operation is valid for magnetic tapes
only. On the multibus data gets byte swapped. rwmt does
byte swapping in software so that the tape gets written
out in the correct machine order. wbak and rbak do not do
byte swapping in software, as a result the two swaps done
by the multibus cancel out. This option is useful in
writing to a magnetic tape an intermediate file to which
wbak output has been directed. Byte swapping should not be
done by rwmt if the intermediate file written by wbak is
now written raw to the magnetic tape using rwmt.
-reten Retension the cartridge tape (unwind to the end, then
rewind). This can be helpful if you have encountered
cartridge-tape reading errors. Retensioning requires
about 1.5 minutes to complete.
-nreten (default)
Do not retension the cartridge tape.
Miscellaneous Control Options
-sbin Cause all stream files written to contain the binary
attribute (normally, output stream files contain the ASCII
attribute).
-p Cause rwmt to prompt for all unspecified parameters.
EXAMPLES
Initialize a tape with the given owner and volume ID.
$ rwmt -label -own "R and D" -vid "demo"
Copy the wildcarded files to tape.
$ rwmt -w c?*_example -f 1 -rf d -rl 200 -bl 2048
32 records of "cmf_example" written to tape file 1.
8 records of "cmt_example" written to tape file 2.
4 records of "cpboot_example" written to tape file 3.
25 records of "cpf_example" written to tape file 4.
List the files on the tape.
$ rwmt -index
Volume label:
Volume ID: "DEMO " Owner ID: "R AND D " Access: " "
File/Section File ID Cr Date Acc RF RL BL
1 1 CMF_EXAMPLE 83/02/17 D 200 2048
2 1 CMT_EXAMPLE 83/02/17 D 200 2048
3 1 CPBOOT_EXAMPLE 83/02/17 D 200 2048
4 1 CPF_EXAMPLE 83/02/17 D 200 2048
5 1 CPT_EXAMPLE 83/02/17 D 200 2048
End of file set.
$
Copy tape file 3 to a disk file named cpboot_example.tape.
$ rwmt -r cpboot_example.tape -f 3
4 records read from tape file 3 into
"cpboot_example.tape".
$
rwmt permits a tape file to be read in "raw" mode. In this mode, each
block read from the tape is written into one record in a stream file,
unmodified by the program. To read a file in "raw" mode, you should
specify the maximum record size using the -rl argument. If you do not,
the default value of 80 bytes is used, and any records longer than that
are truncated. Also, undefined record format should be used. For
example
$ rwmt -r -f 1 -rf u -raw -rl 512 rawfile
reads tape file number 1 into rawfile, with a maximum record length of
512 bytes.
Files may be written in the same manner:
$ rwmt -w -f 1 -rf u -raw -rl 512 rawfile
The file //backup/tmp1 is written out to the magnetic tape in "raw" mode.
The record length is specified to be 8k and no byte swapping is done in
software. This is useful for writing out an intermediate file to which
wbak has written its output. Note that all tapes written by rwmt must
have a ANSI standard volume label for rbak to be able to read the tape
rwmt -w -f 1 -raw -rl 8192 -nobs //backup/tmp1 -ansi
If rwmt writes a file with -nobs option, you should use -nobs option to
read it using rwmt.
SEE ALSO
More information is available. Type
help rbak For information on restoring or indexing a magnetic media
backup file
help wbak For information on creating a magnetic media backup file
help media For information on removable media