TP(5)

NAME
tp - DEC/mag tape formats

DESCRIPTION
The command tp dumps files to and extracts files from DECtape and magtape. The formats of these tapes are the same except that magtapes have larger directories.

Block zero contains a copy of a stand-alone bootstrap program. See bproc(8).

Blocks 1 through 24 for DECtape (1 through 62 for magtape) contain a directory of the tape. There are 192 (resp. 496) entries in the directory; 8 entries per block; 64 bytes per entry. Each entry has the following format:

    struct {
    	char	pathname[32];
    	unsigned short	mode;
    	char	uid;
    	char	gid;
    	char	unused1;
    	char	size[3];
    	long	modtime;
    	unsigned short	tapeaddr;
    	char	unused2[16];
    	unsigned short	checksum;
    };

The path name entry is the path name of the file when put on the tape. If the pathname starts with a zero word, the entry is empty. It is at most 32 bytes long and ends in a null byte. Mode, uid, gid, size and time modified are the same as described under i-nodes (see file system filsys(5)). The tape address is the tape block number of the start of the contents of the file. Every file starts on a block boundary. The file occupies (size+511)/512 blocks of continuous tape. The checksum entry has a value such that the sum of the 32 words of the directory entry is zero.

Blocks above 25 (resp. 63) are available for file storage.

A fake entry has a size of zero.

SEE ALSO
filsys(5), tp(1)

BUGS
The pathname, uid, gid, and size fields are too small.