Provided by: x11-session-utils_7.6+2_amd64 bug


       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 configured.


       -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


       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.


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


       There  are  several  "special"  rstart keywords defined for rstartd configuration.  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 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.

               Gives the prefix for the configuration environment variables rstartd passes to its

       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 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 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 compiled 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 substitute 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