C++ definition

Launches an external OS process in the background, using the command line given in the 'command' parameter. The process is terminated when the module is deleted. This module requires using the ~RealTimeScheduler class as the simulation event scheduler.

To run a command that requires elevated privileges without sudo, user and network namespaces need to be unshared from the host OS (unshare-namespaces = true). In this case, the state of the host OS's external processes are not accessible from the unshared namespace in the usual way (e.g. displaying routing tables with ip route). To work around this, use nsenter:

sudo nsenter -t <PID> -n <command>

PID is the ID of the process running in the unshared namespace.

To list process IDs in all network namespaces:

sudo lsns -t net

<b>See also:</b> ~ExternalApp, ~ExternalEnvironment

Inheritance diagram

The following diagram shows inheritance relationships for this type. Unresolved types are missing from the diagram.

Used in compound modules

Name	Type	Description
ExternalApp	compound module	Provides an external application that uses a host OS external process.

Extends

Name	Type	Description
SimpleModule	simple module	Base module for all INET simple modules.

Parameters

Name	Type	Default value	Description
displayStringTextFormat	string	""	Determines the text that is written on top of the submodule, supports displaying pars, watches, and module-specific information
namespace	string	""	Name of the OS network namespace (optional)
command	string		Executable with arguments (e.g. "ping google.com"); not a shell command as it will be passed to execvp
onExit	string	"ignore"	Determines what happens when the process exits
startTime	double	0s
relaunchDelay	double	0s
printStdout	bool	false	Print STDOUT to the simulation's STDOUT
printStderr	bool	true	Print STDERR to the simulation's STDERR

Properties

Name	Value	Description
class	ExternalProcess
display	i=block/app

Source code

//
// Launches an external OS process in the background, using the command line
// given in the 'command' parameter. The process is terminated when the module
// is deleted. This module requires using the ~RealTimeScheduler class as the
// simulation event scheduler.
//
// To run a command that requires elevated privileges without sudo, user and
// network namespaces need to be unshared from the host OS (unshare-namespaces = true).
// In this case, the state of the host OS's external processes are not accessible
// from the unshared namespace in the usual way (e.g. displaying routing tables with `ip route`).
// To work around this, use `nsenter`:
//
//    sudo nsenter -t <PID> -n <command>
//
// PID is the ID of the process running in the unshared namespace.
//
// To list process IDs in all network namespaces:
//
//    sudo lsns -t net
//
// @see ~ExternalApp, ~ExternalEnvironment
//
simple ExternalProcess extends SimpleModule
{
    parameters:
        @class(ExternalProcess);
        string namespace = default(""); // Name of the OS network namespace (optional)
        string command; // Executable with arguments (e.g. "ping google.com"); not a shell command as it will be passed to execvp
        string onExit @enum("terminateSimulation","relaunch","ignore") = default("ignore"); // Determines what happens when the process exits
        double startTime @unit(s) = default(0s);
        double relaunchDelay @unit(s) = default(0s);
        bool printStdout = default(false); // Print STDOUT to the simulation's STDOUT
        bool printStderr = default(true); // Print STDERR to the simulation's STDERR
        @display("i=block/app");
}

File: src/inet/common/ExternalProcess.ned

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