rosshell

Two simple nodes that can be used as mediators for shell commands.

Author: André Dietrich & Sebastian Zug
License: BSD
Source: https://gitlab.com/andre-dietrich/rosshell

1. Overview

This package provides the two nodes, that enable to run and interact with different non-ros-programs. rosshell can be used to start a program or any kind of shell-command. If some kind of interaction with the programs is required, use rosshellX to receive and send messages from stdin, stdout, and stderr.

2. Usage

The required commands are always defined as a string:

$ rosrun rosshell rosshell.py "command"

$ rosrun rosshell rosshellX.py "command"

have a look at the examples or at the included launch-files.

3. Examples

3.1 rosshell

This command is just used to generate some random noise …

$ rosrun rosshell rosshell.py "aplay -c 2 -f S16_LE -r 44100 /dev/urandom"

Pipe the results of /dev/random into a text file …

$ rosrun rosshell rosshell.py "cat /dev/random > test.txt"

or the some information about the current directory …

$ rosrun rosshell rosshell.py "ls -Shal > test.txt"

3.2 rosshellX

This node is used if you require some interaction with stdin, stdout, and stderr.

rosshellX is by default subscribed to /rosshellX/stdin and publishes at topic /rosshellX/stdout and /rosshellX/stderr, all of type std_msgs/String.

3.2.1 Some basic calculations

bc is just a simple commandline-calculator

1. open three shells

2. start bc with the following command:

   $ rosrun rosshell rosshellX.py "bc"
   

1. print the the results of bc stdout by running:

   $ rostopic echo /rosshellX/stdout
   

1. and now, send some inputs like:

   $ rostopic pub /rosshellX/stdin std_msgs/String "99*99\n"
   $ rostopic pub /rosshellX/stdin std_msgs/String "sqrt(2.0)\n"
   $ rostopic pub /rosshellX/stdin std_msgs/String "33^3\n"
   $ rostopic pub /rosshellX/stdin std_msgs/String "quit\n"
   

1. to interact a bit with stderr, simply subscribe for:

   $ rostopic echo /rosshellX/stderr
   

and publish some nonsense like

   $ rostopic pub /rosshellX/stdin std_msgs/String "wtf\n"
   

3.2.1 Additional functionality

To get some filesystem-information try:

$ rosrun rosshell rosshellX.py "ls -Shal"

or

$ rosrun rosshell rosshellX.py _command:="ls -Shal"

both are the same but you also have the possibility to change the command and topics, also within the launch-file, have a look at rosshellX.launch …

<node pkg="rosshell" type="rosshellX.py" name="rosshellBC">
  <param name="command" type="String" value="bc" />
  <param name="stdout"  type="String" value="bc/stdout" />
  <param name="stdout"  type="String" value="bc/stderr" />
  <param name="stdin"   type="String" value="bc/stdin" />
</node>

4. Nodes

4.1 rosshell

Allows to run commands with no interaction possibilities.

4.2 rosshellX

Allows to run commands and enables an interaction over stdin and stdout.

4.2.1 Subscribed Topics

/rosshellX/stdin (std_msgs/String)

The standard topic for stdin.

4.2.2 Published Topics

/rosshellX/stdout (std_msgs/String)

The current line of the stdout.

/rosshellX/stderr (std_msgs/String)

The current line of the stderr.

4.2.3 Parameters

command (string, default: “”)

Commands that will be executed.

stdout (string, default: /rosshellX/stdout)

Change the topic for stdout.

stdin (string, default: /rosshellX/stdin)

Change the topic for stdin.

stderr (string, default: /rosshellX/stderr)

Change the topic for stderr.