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OPUS Projektor Manual

JavaScript

This function executes any command on the Linux system console.

We cannot stress enough that it is very easy to slow down or even completely stop the PClient

misusing this command, it is even possible to destroy almost all data on the device.

But we also know that it can be very useful in certain situations, e.g. to be able to change the

boot logo on a device at runtime.

Prototype:

var ret = runSystemCommand(string command, bool

waitForFinished, bool returnCommandOutput);

Parameters:

command: A string with the command to execute

waitForFinished: Optional bool flag. If set to true (which is also default if the parameter is

not set), PClient main loop waits until the command has finished. If set to false, the

function will return immediately but the caller will not know the final result of the command

returnCommandOutput: If this flag is set to true, this function will return the complete

console output of the executed command instead of the return value. This parameter is

also optional, if not set, the default value is false. Note: If set to true, waitForFinished also

needs to be true.

Return values:

true if the command executed successfully while returnCommandOutput was set to false

or not set

A string containing the complete output of the executed command if

returnCommandOutput was set to true

If anything fails, an exception is thrown and the execution of the whole script file is

interrupted at the line of the system call. Surround with try/catch block for error handling.

Good example:

var ret = runSystemCommand("top -n 1", true, true);

Bad example:

var ret = runSystemCommand("top", true, true);

Why is it bad? The example will never return because top will keep running, thus the

JavaScript file will never finish.

Good example:

var ret = runSystemCommand("rm -rf /opt/data/own_data", true,

false);

Bad example:

var ret = runSystemCommand("rm -rf /opt/*", true, false);