1RSTARTD(1) General Commands Manual RSTARTD(1)
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6 rstartd - a sample implementation of a Remote Start rsh helper
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9 rstartd
10 rstartd.real [-c configfilename]
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14 Rstartd is an implementation of a Remote Start "helper" as defined in
15 "A Flexible Remote Execution Protocol Based on rsh".
16 This document describes the peculiarities of rstartd and how it is con‐
18 figured.
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21 -c configfilename
22 This option specifies the "global" configuration file that
23 rstartd is to read. Normally, rstartd is a shell script that
24 invokes rstartd.real with the -c switch, allowing local config‐
25 uration of the location of the configuration file. If
26 rstartd.real is started without the -c option, it reads
27 /usr/lib/X11/rstart/config.
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30 It is critical to successful interoperation of the Remote Start proto‐
31 col that rstartd be installed in a directory which is in the "default"
32 search path, so that default rsh requests and the ilk will be able to
33 find it.
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36 Rstartd is by design highly configurable. One would like things like
37 configuration file locations to be fixed, so that users and administra‐
38 tors can find them without searching, but reality is that no two ven‐
39 dors will agree on where things should go, and nobody thinks the origi‐
40 nal location is "right". Thus, rstartd allows one to relocate all of
41 its files and directories.
42 Rstartd has a hierarchy of configuration files which are executed in
44 order when a request is made. They are:
45 global config
46 per-user ("local") config
47 global per-context config
48 per-user ("local") per-context config
49 config from request
50 As you might guess from the presence of "config from request", all of
51 the config files are in the format of an rstart request. Rstartd
52 defines a few additional keywords with the INTERNAL- prefix for speci‐
53 fying its configuration.
54 Rstartd starts by reading and executing the global config file. This
56 file will normally specify the locations of the other configuration
57 files and any systemwide defaults.
58 Rstartd will then read the user's local config file, default name
60 $HOME/.rstart.
61 Rstartd will then start interpreting the request.
63 Presumably one of the first lines in the request will be a CONTEXT
65 line. The context name is converted to lower case.
66 Rstartd will read the global config file for that context, default name
68 /usr/lib/X11/rstart/contexts/<name>, if any.
69 It will then read the user's config file for that context, default name
71 $HOME/.rstart.contexts/<name>, if any.
72 (If neither of these exists, rstartd aborts with a Failure message.)
74 Rstartd will finish interpreting the request, and execute the program
76 specified.
77 This allows the system administrator and the user a large degree of
79 control over the operation of rstartd. The administrator has final
80 say, because the global config file doesn't need to specify a per-user
81 config file. If it does, however, the user can override anything from
82 the global file, and can even completely replace the global context
83 config files.
84 The config files have a somewhat more flexible format than requests do;
86 they are allowed to contain blank lines and lines beginning with "#"
87 are comments and ignored. (#s in the middle of lines are data, not
88 comment markers.)
89 Any commands run are provided a few useful pieces of information in
91 environment variables. The exact names are configurable, but the sup‐
92 plied defaults are:
93 $RSTART_CONTEXT the name of the context
94 $RSTART_GLOBAL_CONTEXTS the global contexts directory
95 $RSTART_LOCAL_CONTEXTS the local contexts directory
96 $RSTART_GLOBAL_COMMANDS the global generic commands directory
97 $RSTART_LOCAL_COMMANDS the local generic commands directory
98 $RSTART_{GLOBAL,LOCAL}_CONTEXTS should contain one special file, @List,
99 which contains a list of the contexts in that directory in the format
100 specified for ListContexts. The supplied version of ListContexts will
101 cat both the global and local copies of @List.
102 Generic commands are searched for in several places: (defaults)
104 per-user per-context directory ($HOME/.rstart.commands/<context>)
105 global per-context directory (/usr/lib/X11/rstart/commands/<context>)
106 per-user all-contexts directory ($HOME/.rstart.commands)
107 global all-contexts directory (/usr/lib/X11/rstart/commands)
108 (Yes, this means you can't have an all-contexts generic command with
109 the same name as a context. It didn't seem like a big deal.)
110 Each of these directories should have a file called @List that gives
112 the names and descriptions of the commands in that directory in the
113 format specified for ListGenericCommands.
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116 There are several "special" rstart keywords defined for rstartd config‐
117 uration. Unless otherwise specified, there are no defaults; related
118 features are disabled in this case.
119 INTERNAL-REGISTRIES name ...
121 Gives a space-separated list of "MISC" registries that this
122 system understands. (Registries other than this are accepted
123 but generate a Warning.)
124 INTERNAL-LOCAL-DEFAULT relative_filename
126 Gives the name ($HOME relative) of the per-user config file.
127 INTERNAL-GLOBAL-CONTEXTS absolute_directory_name
129 Gives the name of the system-wide contexts directory.
130 INTERNAL-LOCAL-CONTEXTS relative_directory_name
132 Gives the name ($HOME relative) of the per-user contexts direc‐
133 tory.
134 INTERNAL-GLOBAL-COMMANDS absolute_directory_name
136 Gives the name of the system-wide generic commands directory.
137 INTERNAL-LOCAL-COMMANDS relative_directory_name
139 Gives the name ($HOME relative) of the per-user generic com‐
140 mands directory.
141 INTERNAL-VARIABLE-PREFIX prefix
143 Gives the prefix for the configuration environment variables
144 rstartd passes to its kids.
145 INTERNAL-AUTH-PROGRAM authscheme program argv[0] argv[1] ...
147 Specifies the program to run to set up authentication for the
148 specified authentication scheme. "program argv[0] ..." gives
149 the program to run and its arguments, in the same form as the
150 EXEC keyword.
151 INTERNAL-AUTH-INPUT authscheme
153 Specifies the data to be given to the authorization program as
154 its standard input. Each argument is passed as a single line.
155 $n, where n is a number, is replaced by the n'th argument to
156 the "AUTH authscheme arg1 arg2 ..." line.
157 INTERNAL-PRINT arbitrary text
159 Prints its arguments as a Debug message. Mostly for rstartd
160 debugging, but could be used to debug config files.
161
163 When using the C shell, or any other shell which runs a script every
164 time the shell is started, the script may get run several times. In
165 the worst case, the script may get run three times:
166 By rsh, to run rstartd
167 By rstartd, to run the specified command
168 By the command, eg xterm
169 rstartd currently limits lines, both from config files and requests, to
170 BUFSIZ bytes.
171 DETACH is implemented by redirecting file descriptors 0,1, and 2 to
173 /dev/null and forking before executing the program.
174 CMD is implemented by invoking $SHELL (default /bin/sh) with "-c" and
176 the specified command as arguments.
177 POSIX-UMASK is implemented in the obvious way.
179 The authorization programs are run in the same context as the target
181 program - same environment variables, path, etc. Long term this might
182 be a problem.
183 In the X context, GENERIC-CMD Terminal runs xterm. In the OpenWindows
185 context, GENERIC-CMD Terminal runs cmdtool.
186 In the X context, GENERIC-CMD LoadMonitor runs xload. In the OpenWin‐
188 dows context, GENERIC-CMD LoadMonitor runs perfmeter.
189 GENERIC-CMD ListContexts lists the contents of @List in both the sys‐
191 tem-wide and per-user contexts directories. It is available in all
192 contexts.
193 GENERIC-CMD ListGenericCommands lists the contents of @List in the sys‐
195 tem-wide and per-user commands directories, including the per-context
196 subdirectories for the current context. It is available in all con‐
197 texts.
198 CONTEXT None is not implemented.
200 CONTEXT Default is really dull.
202 For installation ease, the "contexts" directory in the distribution
204 contains a file "@Aliases" which lists a context name and aliases for
205 that context. This file is used to make symlinks in the contexts and
206 commands directories.
207 All MISC values are passed unmodified as environment variables.
209 One can mistreat rstartd in any number of ways, resulting in anything
211 from stupid behavior to core dumps. Other than by explicitly running
212 programs I don't think it can write or delete any files, but there's no
213 guarantee of that. The important thing is that (a) it probably won't
214 do anything REALLY stupid and (b) it runs with the user's permissions,
215 so it can't do anything catastrophic.
216 @List files need not be complete; contexts or commands which are dull
218 or which need not or should not be advertised need not be listed. In
219 particular, per-user @List files should not list things which are in
220 the system-wide @List files. In the future, perhaps ListContexts and
221 ListGenericCommands will automatically suppress lines from the system-
222 wide files when there are per-user replacements for those lines.
223 Error handling is OK to weak. In particular, no attempt is made to
225 properly report errors on the exec itself. (Perversely, exec errors
226 could be reliably reported when detaching, but not when passing the
227 stdin/out socket to the app.)
228 If compiled with -DODT1_DISPLAY_HACK, rstartd will work around a bug in
230 SCO ODT version 1. (1.1?) (The bug is that the X clients are all com‐
231 piled with a bad library that doesn't know how to look host names up
232 using DNS. The fix is to look up a host name in $DISPLAY and substi‐
233 tute an IP address.) This is a trivial example of an incompatibility
234 that rstart can hide.
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237 rstart(1), rsh(1), A Flexible Remote Execution Protocol Based on rsh
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240 Jordan Brown, Quarterdeck Office Systems
241X Version 11 rstart 1.0.2 RSTARTD(1)