NAME
read20 - read a tape produced by the TOPS-20 Dumper Program
SYNOPSIS
read20 [-f tapefile] [-t] [-x] [-v] [-c] [-T] [-g] [-e
expression] [-S ssnums...] [-F filenums...] [string...]
DESCRIPTION
Read20 reads tapes produced by the TOPS-20 backup and
archival program DUMPER, producing directory listings and
extracting files. The -t option specifies a directory list-
ing, and the -x option specifies extraction. Both actions
can be specified.
If no string, -e, -F, or -S option is given, every file on
the tape is processed. Otherwise, every file with a name
that either contains string ..., matches (as in ed(1)) the
regular expression expression, or is selected by the -S and
-F options will be processed. The last two options are used
to select files by saveset number and file number. This is
useful when extracting from an archive tape. The most-
recently specified saveset number is associated with the
specified file numbers. The TOPS-20 filenames are lower-
cased before any matching. Note that string is not a gen-
eralized pattern, but is just a simple string that is
matched against all the characters in the filenames. Spe-
cial characters (such as '<' and '>') must be quoted to get
past the shell.
The UNIX filename of an extracted file is generated from the
TOPS-20 filename by stripping off the device name, translat-
ing the TOPS-20 directory syntax to a relative directory in
UNIX format, and stripping off the generation number, unless
the -g flag is given. Directories will be built as needed
with protection 775, but any existing directory or its con-
tents will not be changed (unless an extracted file replaces
one of the same name).
The directory listing prints out for every file
-- a ``flags'' field which indicates if the file is
archived (A), offline (O), or invisible (I)
-- the size in TOPS-20 pages (for offline files the
size before archiving)
-- the number of bytes in the file
-- the bytesize (number of bits per byte) of the file
-- the octal TOPS-20 file protection
-- the time and date the file was last modified
-- the full pathname of the file.
If the -v flag is given, two additional fields are printed
at the left:
-- the saveset number
-- the file number
Read20 only extracts text files and 8-bit files. In text
files, unless the -c flag is given, carriage returns preced-
ing linefeeds are removed. The file length as printed by
the `t' option is not adjusted to account for this. Read20
decides whether or not a file is text by examining the
bytesize of the file. If the file has 7-bit bytes, it is
assumed to be a text file. If it has 8-bit bytes, it is
extracted at 4 bytes/word, including null bytes. If the
file has any other bytesize, requests to extract it are
ignored.
Occasionally, text files have a bytesize of 36 or 0 instead
of the proper bytesize of 7. The -T flag forces these files
to be considered as text files.
Alternate tape devices or files may be specified with the -f
flag. The special filename `-' signifies the standard
input.
On non-Berkeley Unix systems, name collisions can occur when
the first 14 characters of extracted files are the same. If
this is the case, use the -n <number> option. This will
cause the Unix filenames to be numeric, starting with the
number following the -n. The mapping from the original
TOPS-20 to the numeric Unix filenames is written to the file
`` Logfile '' in the current directory.
FILES
/dev/rmt8 - default tapefile.
AUTHOR
Jim Guyton, The Rand Corporation
Jay Lepreau, University of Utah
BUGS
Files which span tape boundaries are handled poorly. To
extract such a file, extract each piece and then combine the
files under UNIX.
Directory descriptor blocks on the tape are not interpreted.
Offline files usually show up in directory listings with a
zero bytesize.