/usr/bin/rtd is in skycat 3.1.2+starlink1~b+dfsg-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53  | #!/bin/sh
# Start script for rtd
#
# "@(#) $Id: rtd.in,v 1.1.1.1 2009/03/31 14:11:52 cguirao Exp $"
#
# who         when       what
# --------   ---------   ----------------------------------------------
# A.Brighton 28 Jan 06   created
# pbiereic   29/12/08    ignore error output from 'ps -x'
# Determine rtd base dir, following any symbolic links, if needed.
PRG="$0"
cwd=`pwd`
cd `dirname "$PRG"`
while [ -h "$PRG" ]; do
    ls=`ls -ld "$PRG"`
    link=`expr "$ls" : '.*-> \(.*\)$'`
    if expr "$link" : '.*/.*' > /dev/null; then
        PRG="$link"
    else
        PRG=`dirname "$PRG"`/"$link"
    fi
done
DIR=`dirname "$PRG"`/..
RTD_BASE=`(cd $DIR; pwd)`
cd $cwd
# If we're NOT ssh'd in
if [ ! "${SSH_TTY}" ]; then
    # make sure X is running (on Mac OS X)
    if [ `uname` = "Darwin" -a "`ps -x 2>/dev/null | awk '{print $5}' | grep X11`" = "" ]; then
	for i in /Applications/Utilities $HOME/Desktop ; do
	    if [ -e $i/X11.app ] ; then
		open $i/X11.app &
	    fi
	done
    fi
    # Make sure DISPLAY is set
    if [ x${DISPLAY} = x ]; then
	export DISPLAY=:0
    fi
fi
# Make sure we can find the Tcl packages
TCLLIBPATH="/usr/lib/skycat /usr/share/skycat"
export TCLLIBPATH
# Make sure we start the correct wish binary
PATH=$RTD_BASE/bin:$PATH
export PATH
test -d $HOME/.rtd || mkdir $HOME/.rtd
exec wish8.6 /usr/share/skycat/rtd3.2.1/main.tcl ${1+"$@"} | tee $HOME/.skycat/log 2>&1
 |