73 lines
1.6 KiB
Groff
73 lines
1.6 KiB
Groff
.\" @(#)tp.5 1.1 92/07/30 SMI; from UCB 4.2
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.TH TP 5 "18 June 1983"
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.SH NAME
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tp \- DEC/mag tape formats
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.SH DESCRIPTION
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.IX "tp file" "" "\fLtp\fP \(em DEC/mag tape formats"
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.I Tp
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dumps files to and extracts files from
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DECtape and magtape.
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The formats of these tapes are the same except
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that magtapes have larger directories.
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.PP
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Block zero contains a
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copy of a stand-alone bootstrap program.
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See
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.IR reboot (8).
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.PP
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Blocks 1 through 24
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for DECtape (1 through 62 for magtape)
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contain a directory of the tape.
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There are 192 (resp. 496) entries in the directory;
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8 entries per block;
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64 bytes per entry.
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Each entry has the following format:
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.nf
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.IP ""
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.ta 8n +\w'unsigned short 'u
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struct {
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char pathname[32];
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unsigned short mode;
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char uid;
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char gid;
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char unused1;
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char size[3];
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long modtime;
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unsigned short tapeaddr;
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char unused2[16];
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unsigned short checksum;
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};
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.fi
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.DT
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.PP
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The path name entry is the path name of the
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file when put on the tape.
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If the pathname starts with a zero word,
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the entry is empty.
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It is at most 32 bytes long and ends in a null byte.
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Mode, uid, gid, size and time modified
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are the same as described under i-nodes
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(see file system
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.IR fs (5)).
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The tape address is the tape block number of the start of
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the contents of the file.
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Every file
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starts on a block boundary.
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The file occupies (size+511)/512 blocks
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of continuous tape.
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The checksum entry has a value such that
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the sum of the 32 words of the directory entry is zero.
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.PP
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Blocks above 25 (resp. 63) are available for file storage.
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.PP
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A fake entry
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has a size of zero.
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.SH "SEE ALSO"
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fs(5)
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.SH BUGS
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The
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.I pathname, uid, gid,
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and
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.I size
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fields are too small.
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