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rstartd(1X)
X11R6
NAME
  rstartd - a sample implementation of a Remote Start rsh helper

SYNOPSIS
  rstartd, rstartd.real [-c configfilename]

OPTIONS
  -c configfilename
      This option specifies the "global" configuration file that rstartd is
      to read.	Normally, rstartd is a shell script that invokes rstartd.real
      with the -c switch, allowing local configuration of the location of the
      configuration file.  If rstartd.real is started without the -c option,
      it reads <XRoot>/lib/X11/rstart/config, where <XRoot> refers to the
      root of the X11 install tree.

DESCRIPTION
  rstartd is an implementation of a Remote Start "helper" as defined in A
  Flexible Remote Execution Protocol Based on rsh.

  This document describes the peculiarities of rstartd and how it is
  configured.

INSTALLATION
  It is critical to successful interoperation of the Remote Start protocol
  that rstartd be installed in a directory which is in the "default" search
  path, so that default rsh requests and the ilk will be able to find it.

CONFIGURATION AND OPERATION
  rstartd is by design highly configurable.  One would like things like
  configuration file locations to be fixed, so that users and administrators
  can find them without searching, but reality is that no two vendors will
  agree on where things should go, and nobody thinks the original location is
  "right".  Thus, rstartd allows one to relocate all of its files and
  directories.

  rstartd has a hierarchy of configuration files which are executed in order
  when a request is made.  They are:

       global config
       per-user ("local") config
       global per-context config
       per-user ("local") per-context config
       config from request

  As you might guess from the presence of "config from request", all of the
  config files are in the format of an rstart request.	rstartd defines a few
  additional keywords with the INTERNAL- prefix for specifying its
  configuration.

  rstartd starts by reading and executing the global config file. This file
  will normally specify the locations of the other configuration files and
  any systemwide defaults.

  rstartd will then read the user's local config file, default name
  $HOME/.rstart.

  rstartd will then start interpreting the request.

  Presumably one of the first lines in the request will be a CONTEXT line.
  The context name is converted to lower case.

  rstartd will read the global config file for that context, default name
  <XRoot>/lib/X11/rstart/contexts/<name>, if any.

  It will then read the user's config file for that context, default name
  $HOME/.rstart.contexts/<name>, if any.

  (If neither of these exists, rstartd aborts with a Failure message.)

  rstartd will finish interpreting the request, and execute the program
  specified.

  This allows the system administrator and the user a large degree of control
  over the operation of rstartd.  The administrator has final say, because
  the global config file does not need to specify a per-user config file. If
  it does, however, the user can override anything from the global file, and
  can even completely replace the global context config files.

  The config files have a somewhat more flexible format than requests do;
  they are allowed to contain blank lines and lines beginning with "#" are
  comments and ignored.	 (#s in the middle of lines are data, not comment
  markers.)

  Any commands run are provided a few useful pieces of information in
  environment variables.  The exact names are configurable, but the supplied
  defaults are:

       $RSTART_CONTEXT		   the name of the context
       $RSTART_GLOBAL_CONTEXTS	   the global contexts directory
       $RSTART_LOCAL_CONTEXTS	   the local contexts directory
       $RSTART_GLOBAL_COMMANDS	   the global generic commands directory
       $RSTART_LOCAL_COMMANDS	   the local generic commands directory

  $RSTART_{GLOBAL,LOCAL}_CONTEXTS should contain one special file, @List,
  which contains a list of the contexts in that directory in the format
  specified for ListContexts.  The supplied version of ListContexts will cat
  both the global and local copies of @List.

  Generic commands are searched for in several places: (defaults)

       per-user per-context directory ($HOME/.rstart.commands/<context>)
       global per-context directory
			     (<XRoot>/lib/X11/rstart/commands/<context>)
       per-user all-contexts directory ($HOME/.rstart.commands)
       global all-contexts directory (<XRoot>/lib/X11/rstart/commands)

  (Yes, this means you cannot have an all-contexts generic command with the
  same name as a context.  It did not seem like a big deal.)

  Each of these directories should have a file called @List that gives the
  names and descriptions of the commands in that directory in the format
  specified for ListGenericCommands.

CONFIGURATION KEYWORDS
  There are several "special" rstart keywords defined for rstartd
  configuration.  Unless otherwise specified, there are no defaults; related
  features are disabled in this case.

  INTERNAL-REGISTRIES name ...
      Gives a space-separated list of "MISC" registries that this system
      understands.  (Registries other than this are accepted but generate a
      Warning.)

  INTERNAL-LOCAL-DEFAULT relative_filename
      Gives the name ($HOME relative) of the per-user config file.

  INTERNAL-GLOBAL-CONTEXTS absolute_directory_name
      Gives the name of the system-wide contexts directory.

  INTERNAL-LOCAL-CONTEXTS relative_directory_name
      Gives the name ($HOME relative) of the per-user contexts directory.

  INTERNAL-GLOBAL-COMMANDS absolute_directory_name
      Gives the name of the system-wide generic commands directory.

  INTERNAL-LOCAL-COMMANDS relative_directory_name
      Gives the name ($HOME relative) of the per-user generic commands
      directory.

  INTERNAL-VARIABLE-PREFIX prefix
      Gives the prefix for the configuration environment variables rstartd
      passes to its kids.

  INTERNAL-AUTH-PROGRAM

  authscheme program argv[0] argv[1] ...
      Specifies the program to run to set up authentication for the specified
      authentication scheme.  "program argv[0] ..." gives the program to run
      and its arguments, in the same form as the EXEC keyword.

  INTERNAL-AUTH-INPUT authscheme
      Specifies the data to be given to the authorization program as its
      standard input.  Each argument is passed as a single line. $n, where n
      is a number, is replaced by the  nth argument to the "AUTH authscheme
      arg1 arg2 ..." line.

  INTERNAL-PRINT arbitrary text
      Prints its arguments as a Debug message.	Mostly for rstartd debugging,
      but could be used to debug config files.

NOTES
  When using the C shell, or any other shell which runs a script every time
  the shell is started, the script may get run several times. In the worst
  case, the script may get run three times:

       By rsh, to run rstartd
       By rstartd, to run the specified command
       By the command, for example, xterm

  rstartd currently limits lines, both from config files and requests, to
  BUFSIZ bytes.

  DETACH is implemented by redirecting file descriptors 0,1, and 2 to
  /dev/null and forking before executing the program.

  CMD is implemented by invoking $SHELL (default /bin/sh) with -c and the
  specified command as arguments.

  POSIX-UMASK is implemented in the obvious way.

  The authorization programs are run in the same context as the target
  program -- same environment variables, path, and so forth.  Long term this
  might be a problem.

  In the X context, GENERIC-CMD Terminal runs xterm. In the OpenWindows
  context, GENERIC-CMD Terminal runs cmdtool.

  In the X context, GENERIC-CMD LoadMonitor runs xload. In the OpenWindows
  context, GENERIC-CMD LoadMonitor runs perfmeter.

  GENERIC-CMD ListContexts lists the contents of @List in both the system-
  wide and per-user contexts directories.  It is available in all contexts.

  GENERIC-CMD ListGenericCommands lists the contents of @List in the system-
  wide and per-user commands directories, including the per-context
  subdirectories for the current context.  It is available in all contexts.

  CONTEXT None is not implemented.

  CONTEXT Default is really dull.

  For installation ease, the "contexts" directory in the distribution
  contains a file "@Aliases" which lists a context name and aliases for that
  context. This file is used to make symlinks in the contexts and commands
  directories.

  All MISC values are passed unmodified as environment variables.

  One can mistreat rstartd in any number of ways, resulting in anything from
  stupid behavior to core dumps.  Other than by explicitly running programs I
  do not think it can write or delete any files, but there's no guarantee of
  that.	 The important thing is that (a) it probably will not do anything
  REALLY stupid and (b) it runs with the user's permissions, so it cannot do
  anything catastrophic.

  @List files need not be complete; contexts or commands which are dull or
  which need not or should not be advertised need not be listed. In
  particular, per-user @List files should not list things which are in the
  system-wide @List files.  In the future, perhaps ListContexts and
  ListGenericCommands will automatically suppress lines from the system-wide
  files when there are per-user replacements for those lines.

  Error handling is OK to weak.	 In particular, no attempt is made to
  properly report errors on the exec itself.  (Perversely, exec errors could
  be reliably reported when detaching, but not when passing the stdin/out
  socket to the app.)

  If compiled with -DODT1_DISPLAY_HACK, rstartd will work around a bug in SCO
  ODT version 1.  (1.1?)  (The bug is that the X clients are all compiled
  with a bad library that does not know how to look host names up using DNS.
  The fix is to look up a host name in $DISPLAY and substitute an IP
  address.) This is a trivial example of an incompatibility that rstart can
  hide.

SEE ALSO
  rstart(1X), rsh(1), A Flexible Remote Execution Protocol Based on rsh

AUTHOR
  Jordan Brown, Quarterdeck Office Systems

Index for Section 1X

Alphabetical listing for R

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