Can I run a bash script using roslaunch?

edit

Better late than never! I came across a similar issue and have implemented a convenient solution. Hopefully many more people can use it, as I find it to be very helpful!

How to use it?

Save the script shown below to a file named "timed_roslaunch.sh". Put it in a scripts/ subfolder of your catkin package. Make it executable using chmod +x. And use it either through command line or a launch file. The scripts help (./timed_roslaunch.sh -h) is shown below:

This script can delay the launch of a roslaunch file
Place it in the 'scripts' folder of your catkin package
and make sure that the file is executable (chmod +x timed_roslaunch.sh)

Run it from command line:

Use: ./timed_roslaunch.sh [number of seconds to delay] [rospkg] [roslaunch file] [arguments (optional)]
Or: rosrun [yourpackage] time_roslaunch.sh [number of seconds to delay] [rospkg] [roslaunch file] [arguments (optional)]
Example: ./timed_roslaunch.sh 2 turtlebot_navigation amcl_demo.launch initial_pose_x:=17.0 initial_pose_y:=17.0

Or run it from another roslaunch file:

<launch>
<arg name="initial_pose_y" default="17.0" />
  <node pkg="semantic_turtle_test" type="timed_roslaunch.sh" 
    args="2 turtlebot_navigation amcl_demo.launch initial_pose_x:=17.0 initial_pose_y:=$(arg initial_pose_y)" 
    name="timed_roslaunch" output="screen">
  </node>
</launch>

The script or use this link.

#!/bin/bash          
#
# Script to delay the launch of a roslaunch file
# 
# Koen Lekkerkerker
# Thu 24 Apr 2014 
#
# Use: ./timed_roslaunch.sh [number of seconds to delay] [rospkg] [roslaunch file]
#

function showHelp(){
    echo 
    echo "This script can delay the launch of a roslaunch file"
    echo "Place it in the 'scripts' folder of your catkin package"
    echo "and make sure that the file is executable (chmod +x timed_roslaunch.sh)"
    echo 
    echo "Run it from command line:"
    echo 
    echo "Use: ./timed_roslaunch.sh [number of seconds to delay] [rospkg] [roslaunch file] [arguments (optional)]"
    echo "Or: rosrun [yourpackage] time_roslaunch.sh [number of seconds to delay] [rospkg] [roslaunch file] [arguments (optional)]"
    echo "Example: ./timed_roslaunch.sh 2 turtlebot_navigation amcl_demo.launch initial_pose_x:=17.0 initial_pose_y:=17.0"
    echo 
    echo "Or run it from another roslaunch file:"
    echo 
    echo '<launch>'
    echo '  <arg name="initial_pose_y" default="17.0" />'
    echo '  <node pkg="semantic_turtle_test" type="timed_roslaunch.sh"'
    echo '    args="2 turtlebot_navigation amcl_demo.launch initial_pose_x:=17.0 initial_pose_y:=$(arg initial_pose_y)"'
    echo '    name="timed_roslaunch" output="screen">'
    echo '  </node>'
    echo '</launch>'
}

if [ "$1" = "-h" ]; then
    showHelp
else 
    echo "start wait for $1 seconds"
    sleep $1
    echo "end wait for $1 seconds"
    shift
        echo "now running 'roslaunch $@'"
    roslaunch $@
fi

Now why did I need it?

My problem was that when I have launch script to launch a fairly large project. Gazebo simulates a world with a simulated turtlebot and gmapping is used for mapping it. It seems that gazebo returns laser measurements before the whole world is spawn. The robot is in a corridor, but as the walls are spawned later than the laser, the first laser measurements give a full free circle. As gmapping already processed these measurements, gmapping incorrectly mapped this circle as free space.

See screenshot:

I also stumbled across this problem and implemented a generic solution. You might want to have a look at the aliencontrol ROS package.

This package contains a node that starts any external application. Almost more importantly, the node also takes care of a clean shutdown, no matter whether the external application or the containing ROS node is terminated.

It is run like so (if you wanted to start your_script.sh):

rosrun aliencontrol aliencontrol /path/to/your_script.sh

If you want to embed it in your launch script, add:

<node pkg="aliencontrol" type="aliencontrol" name="aliencontrol">
    <param name="cmd" value="/path/to/your_script.sh"/>
</node>

See this source code http://www.ros.org/wiki/webots_run for an example of running an executable from a ROS package.