RSTARTD(1)                  General Commands Manual                 RSTARTD(1)

       rstartd - a sample implementation of a Remote Start rsh helper


       rstartd.real [-c configfilename]

       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 con-

       -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 config-
               uration  of  the  location  of  the  configuration  file.    If
               rstartd.real  is  started  without  the  -c  option,  it  reads

       It is critical to successful interoperation of the Remote Start  proto-
       col  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.

       Rstartd  is  by design highly configurable.  One would like things like
       configuration file locations to be fixed, so that users and administra-
       tors  can  find them without searching, but reality is that no two ven-
       dors will agree on where things should go, and nobody thinks the origi-
       nal  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 speci-
       fying 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

       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
       /usr/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

       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 doesn't 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  sup-
       plied defaults are:

       $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 ($HOME/.rstart.commands/<context>)
       global per-context directory (/usr/lib/X11/rstart/commands/<context>)
       per-user all-contexts directory ($HOME/.rstart.commands)
       global all-contexts directory (/usr/lib/X11/rstart/commands)
       (Yes, this means you can't have an all-contexts  generic  command  with
       the same name as a context.  It didn't 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.

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

               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 direc-

       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  com-
               mands directory.

               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 n'th 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.

       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, eg 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, etc.  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 OpenWin-
       dows context, GENERIC-CMD LoadMonitor runs perfmeter.

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

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

       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 don't think it can write or delete any files, but there's no
       guarantee  of  that.  The important thing is that (a) it probably won't
       do anything REALLY stupid and (b) it runs with the user's  permissions,
       so it can't 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 com-
       piled  with  a  bad library that doesn't know how to look host names up
       using DNS.  The fix is to look up a host name in $DISPLAY  and  substi-
       tute  an  IP address.)  This is a trivial example of an incompatibility
       that rstart can hide.

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

       Jordan Brown, Quarterdeck Office Systems

X Version 11                     rstart 1.0.5                       RSTARTD(1)
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