def osCommand(commandStr):
    # by: D@CC
    # date: 2020
    # used by: PiR2
    # aka commandOS()
    # @purpose: to issue a system command and return the result
    # @param1:  str commandStr       eg: "vcgencmd measure_temp"
    # @returns: str commandResultStr eg: "temp=36.9'C"
    
    from subprocess import call
    #import os
    from os import system, name, remove
    from time import sleep


    #print("osCommand received commandStr:"+commandStr)
    commandResultStr="none"

    global g_fileArray

    #commandRFileName=g_fileArray[2]
    commandRFileName="/home/pi/Desktop/PiR2/files/commandResult.txt"
    # name is not a function, but a special variable
    if name == 'nt':
        _ =system('cls')
    else:
        if (commandStr=="clear"):

            print("before clear")
            _= system("clear")
            print("after clear")
        else:
            if (False):
                # in case no file exists, appending something will create it
                # for sure
                fh=open(commandRFileName, "a")
                fh.write("any")
                fh.close()
                # now remove it
                remove(commandRFileName)
            #endif

            # save result in txt file
            saveOutputStr=" >"+commandRFileName
            revisedCommandStr=commandStr+saveOutputStr
            #print("revisedCommandStr:"+revisedCommandStr)

            #invoke system command
            _= system(revisedCommandStr)
            fh=open(commandRFileName, "r")
            # read the result of the command
            commandResultStr=fh.readline()
            fh.close()
        #end if
    return commandResultStr
    #end if
#end def osCommand()