CompareOsEnv gets env named by the key and compare it with comparedEnv.

ExecCommand use shell /bin/bash -c to execute command.

GetOsEnv Getenv retrieves the value of the environment variable named by the key.It returns the value, which will be empty if the variable is not present.To distinguish between an empty value and an unset value, use os.LookupEnv.

SetOsEnv sets the value of the environment variable named by the key.It returns an error, if any.