Environment Variables

This section addresss ToolTalk and related environment variables.

ToolTalk Environment Variables

There are several ToolTalk environment variables that may be set. describes these variables.

Table 4-2 Environment Variables

Variable	Description
`TTSESSION_CMD`	Overrides the standard options specified when tools automatically start `ttsession`. If this variable is set, all ToolTalk clients use this command to automatically start their X sessions.
`TT_ARG_TRACE_WIDTH`	Defines the number of characters of argument and context values to print when in trace mode. The default is to print the first 40 characters.
`TT_FILE`	`ttsession` places a pathname in this variable when a tool is invoked by a message scoped to the defined file.
`TT_HOSTNAME_MAP`	Points to a map file. The defined map file is read into the ToolTalk client for redirecting host machines.
`TT_PARTITION_MAP`	Points to a map file. The defined map file is read into the ToolTalk client for redirecting file partitions.
`TT_SESSION`	`ttsession` communicates its session identifier to the tools that it starts. If this variable is set, the ToolTalk client library uses its value as the default session identifier. The string stored in this variable can be passed to `tt_default_session_set`.
`TT_TOKEN`	Notifies the ToolTalk client library that it has been started by `ttsession`; the client can then confirm to `ttsession` that the start was successful.
`TT_TRACE_SCRIPT`	Tells libtt to turn on client-side tracing as specified in the trace script for `tttrace`(1).
`TTPATH`	Tells the ToolTalk service where the ToolTalk Types databases used by `tt_type_comp`(1) and `rpc.ttdbserverd`(1M) reside.
`CEPATH`	Tells the Classing Engine where the ToolTalk Types databases reside.
`DISPLAY`	Causes `ttsession` to communicate its session identifier to the tools that it starts if the `TT_SESSION` variable is not set. If the DISPLAY variable is set, the ToolTalk client library uses its value as the default session identifier. This variable is typically set when `ttsession` is auto-started while running under OpenWindows. NOTE: Under the Solaris operating environment, this variable may not be passed across to some accounts. That is, if you are logged on the console as User A and switch-user to User B, `ttsession` may not autostart when you attempt to run a ToolTalk program that normally autostarts `ttsession`. To avoid this problem, either manually set the this variable or include it in your `.login` file.
`DTMOUNTPOINT`	If set, the value of this environment variable will be used in place of `/net` in pathnames constructed to answer `tt_host_netfile_file()`(3) queries, by `rpc.ttdbserverd`(1M).

A process is given a modified environment when it is automatically started by the ToolTalk service. The modified environment includes the environment variables $TT_SESSION, $TT_TOKEN, and any contexts in the start-message whose keyword begins with the dollar sign symbol ($). Optionally, the environment variable $TT_FILE may also be included in the modified environment if it is a file-scoped message.

Note - If the tt_open call will be invoked by a child process, the parent process must propagate the modified environment to that child process.

Other Environment Variables

The TMPDIR environment variable is another environment variable that you can set to manipulate the ToolTalk development environment. For example, the following line redirects files to the /var/tmp directory.

TMPDIR=/var/tmp

Environment Variables Required to Start Programs on Remote Hosts

The start string is always executed on the host on which ttsession is running; however, the executed process can start another process on another host.

To do this, first make your start string be similar to the following:

# rsh farhost myprog

Next, to make sure myprog is placed in the right session and receives its initial message, you need to propagate the important ToolTalk environment variables. The ttrsh shell script shown in propagates these environment variables.

Example 4-1 Propagating ToolTalk Environment Variables

#! /bin/sh
# Runs a command remotely in background, by pointing stdout and stderr 
# at /dev/null. By running this through the Bourne shell at the other end, 
# we get rid of the rsh and rshd.
#set -x
user=
debug=
HOST=${HOST-`hostname`}
if [ "$1" = "-debug" ]; then
    debug=1
    shift
fi
if [ $# -lt 2 -o "$1" = "-h" -o "$1" = "-help" ]; 
then
    echo "Usage: ttrsh [-debug] remotehost [-l username] \
remotecommand"
    echo "Usage: ttrsh [-h | -help]"
    exit 1
else
    host=$1
    shift
    if test "$1" = "-l" ; then
        shift
        user=$1
        shift
    fi
fi
xhostname=`expr "$DISPLAY" : "\([^:]*\).*"`
xscreen=`expr "$DISPLAY" : "[^:]*\(.*\)"`
if test x$xscreen = x; then
    xscreen=":0.0"
fi
if test x$xhostname = x -o x$xhostname = x"unix";
then
    DISPLAY=$HOST$xscreen
fi
if [ "$user" = "" ]; then
    userOption=""
else
    userOption="-l $user"
fi
if [ $debug ]; then
    outputRedirect=
else
    outputRedirect='> /dev/null 2>&1 &'
fi
(
    echo "OPENWINHOME=$OPENWINHOME;export OPENWINHOME;\
TT_SESSION=$TT_SESSION;export TT_SESSION;\
TT_TOKEN=$TT_TOKEN;export TT_TOKEN;TT_FILE=$TT_FILE;\
export TT_FILE;DISPLAY=$DISPLAY;export DISPLAY;($*)" \
$outputRedirect | rsh $host $userOption /bin/sh &
) &

Using Context Slots to Create Environment Variables

Message contexts have a special meaning when the ToolTalk service starts an application. If the name of a context slot begins with a dollar sign ($), the ToolTalk service interprets the value as an environment variable. For example, the following uses the value of context slot $CON1.

start "my_application $CON1"