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File Specifications

Information and programs for TOPS-20 are usually  stored  in  uniquely
labeled  files.  Therefore, file specifications or "filespecs" are the
most common variety  of  argument  to  a  command.   A  complete  file
specification is of the form:

     dev:<dir>name.typ.gen;att;...;att

where:

     dev:   is a device (usually a file structure)

     <dir>  is a directory name (enclosed in angle < > or  square  [ ]
            brackets)

     name   is a filename

     .typ   is a file type

     .gen   is a generation number

     ;att   is a file attribute

You need file attributes in only a few situations and can usually  let
dev:,  <dir>,  and .gen take default values, so you can give most file
specifications in the shortened form, name.typ, without being unclear.
(Default  values  are those that are defined by the state of your job.
For more information see the DEFAULTS help file.) In a few  cases,  an
entire file specification is assumed if you do not supply one when you
give the command (for the CREATE and EDIT commands, for  example,  and
for LOAD-class commands - COMPILE, LOAD, EXECUTE, and DEBUG).

Whenever you omit the dev: field of the filespec, the  system  assumes
you  mean  your  connected  structure  (DSK:).   This  is  the  public
structure (usually named PS:), which all users must log in to,  unless
you  connect  to a directory on another structure by using the CONNECT
command.  Give the INFORMATION STRUCTURE command if you are unsure  of
the name for your connected structure.

Whenever you omit the <dir> field of the filespec, the system  assumes
you  mean  your  connected directory.  Unless you have given a CONNECT
command, this is your "log-in" directory, the directory on the  public
structure  that  you  must  log  in  to  and  which usually has a name
composed of your surname, or surname and initials, enclosed  in  angle
or square brackets.  You can change your connected directory by giving
a CONNECT command.  Use the DIRECTORY command to see the name of  your
connected directory.

When you omit the .gen field  of  the  filespec,  the  system  usually
assumes you mean the highest generation (largest generation number) of
the  file.   (A  few  commands,  for  example,  DELETE,  RENAME,   and
DIRECTORY,  act  on  all  generations  of  a file unless you specify a
particular generation.)  When you create and edit text files,  compile
and  debug programs, or do anything else to produce another generation
of a file, the system automatically works with  the  highest  existing
generation and labels the changed file with the next higher generation
number.  Therefore when you omit the generation number in  a  filespec
given  as  argument to a TOPS-20 command, you are assured of using the
most recent version of the  file.   Although  you  can  override  this
default  action  by  specifying  particular  generations  of input and
output files, it is simplest and most  straightforward  to  allow  the
defaults to prevail.

Specification  of  file  attributes  is  optional.   You  can   assign
attributes  in  order to have a file automatically marked for deletion
when you log out; to associate a file with a  valid  account;  and  so
forth.  Appendix C lists the available file attributes.

Pressing the ESC key instead of typing a filespec field  will  usually
cause  any  default  for  the  remaining  fields to be printed on your
terminal.

There are two characters (called "wildcard" characters) that  you  can
include  in  any field of a filespec to include all files matching the
rest of the filespec.  An asterisk (*)  fills  in  for  zero  or  more
characters  of a field, while a percent sign (%) fills in for a single
character only.  (However, only the complete field "DSK*:" is  allowed
as  wildcard  for the device field, and only the complete field "*" is
allowed as wildcard for the generation field.)   Therefore  you  could
give the command DIRECTORY *.CBL to find out what source files written
in COBOL are in your connected directory, or the command  DELETE  *.Q*
to remove the EDIT program's backup files from your directory.