- 'preinstall_cmd': Parameter(str, "Shell command to execute prior to installing", max = 1024),
- 'postinstall_cmd': Parameter(str, "Shell command to execute after installing", max = 1024),
- 'error_cmd': Parameter(str, "Shell command to execute if any error occurs", max = 1024),
+ 'preinstall_cmd': Parameter(str, "Shell command to execute prior to installing", max = 1024, nullok = True),
+ 'postinstall_cmd': Parameter(str, "Shell command to execute after installing", max = 1024, nullok = True),
+ 'error_cmd': Parameter(str, "Shell command to execute if any error occurs", max = 1024, nullok = True),