.TH FSIO-DOSMT 1 "Jun 25,2019" "FFS I/O - DOS-11 magtape"
.SH NAME
fsio-dosmt \- Foreign File System I/O - DOS-11 magtape
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.SH DESCRIPTION
\fBfsio\fP allows access to DOS-11 magtapes using the file system type
"\fIdosmt\fP"
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.SH WILDCARD CHARACTERS
The wildcard character \fI'*'\fP may be used to match filename, extension,
group number and user number. Wildcard characters may be used with the
\fIdir\fP command to limit the number of files being displayed. They may also
be used with commands to read files; \fIdump\fP, \fItype\fP and \fIcopy\fP
(only the source file for \fIcopy\fP), in which case the next file which
matches the wildcard character(s) will be used for input. As a consequence
of this, the empty filename may be used to select the next file on the tape,
so:
.RS

fsio> type mt:
.RE

will type the next file on the tape.
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.SH MOUNT OPERATION
DOS/BATCH-11 defined magtape headers to be 14 bytes long with 2 bytes unused.
Some tapes use these unused bytes to add an additional 3 characters to the
filename (e.g. ABCDEFGHI.EXT rather than ABCDEF.EXT). By default, fsio will
ignore these unused bytes. If the \fI-x\fP switch is used on the \fImount\fP
command, fsio will make use of the extra 3 characters on file lookup,
directory listing and file creation.
.SH NEWFS OPERATION
\fInewfs\fP creates an empty (zero length) file.
.SH SET OPERATION
The following \fIset\fP commands are supported:
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.TP
.B "\fIuic\fP [proj,prog]"
Sets the default UIC for file access (was [1,1] after mount).
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.RS
.RS
.B "\fIproj\fP    \- Project number (octal 1 - 377)"
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.B "\fIprog\fP    \- Programmer number (octal 1 - 377)"
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.RE
.RE
.TP
.B "\fIprot\fP <code>"
Set the default protection code when writing new files to magtape.
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.RS
.RS
.B "\fIprot\fP    \- Protection code (octal 0 - 377)"
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.RE
.RE
.SH INFO OPERATION
\fIinfo\fP displays where the tape is currently positioned. If the tape is
not positioned at the end and it is not an empty tape, the name of the next
file after the current position will be displayed.
.SH NOTES
DOS-11 magtapes differ from disk-based file systems in a number of ways:
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.RS
1. Filenames are not unique on a magtape.
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2. The tape has to be positioned before writing a new file to 
   avoid over-writing an existing file.
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.RE

Assuming a magtape is mounted on mt: and has 5 files on it:
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The sequence:
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.RS

fsio> rewind mt:
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fsio> copy -a a.b mt:c.d
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.RE

will result in the tape containing a single file (c.d), while the sequence:
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.RS

fsio> eom mt:
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fsio> copy -a a.b mt:c.d
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.RE

will result in the tape containing 6 files (the original 5 followed by c.d).
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By using skipf/skipr commands it is possible to position the tape just past
the end of any specific file (see info command for more details on how to
determine the current tape position).
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.SH SEE ALSO
.BR fsio (1)
.BR fsio-dos11 (1)
.BR fsio-rt11 (1)
.BR fsio-os8 (1)
.SH AUTHOR
John Forecast, <john@forecast.name>
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