3.4.2.4 Tool Invocation

The invocation of a tool follows some conventions which allow a wide range of tools to operate within these conditions, and furthermore enhance the transparency of tool invocation.

• The program defined by command is invoked using a working directory (invocation directory) dedicated to one invocation of a tool. It should be stressed that several concurrent invocations -- which are performed in parallel -- use different directories. This means that each invocation of a tool uses a separate directory rather than just each tool. Furthermore, this directory can be anywhere and no assumptions are made about its location; the invoked program must not make any assumptions -- except the conventions stated here -- about this location or the content of its invocation directory.

• The evaluated command line template is stored to a file named "cmdline". This file will be especially useful when a problem related to the invocation of a simulation program needs to be fixed.

• All input deck templates will be evaluated and stored into files with filenames according to their associated keys tpl-key. This means that a template defined using the key file-a in the tool's definition, will lead to a file named "file-a" in the invocation directory.

• For each result defined in the results section (see above) the program has to write a file to the invocation directory of the tool evaluation, which is also its working directory.

• The standard output and the standard error output of the simulation tool is recorded to files in the invocation directory named log and errorlog.

In fact, it turns out that these requirements can easily be fulfilled by simulation tools. Moreover, the users of SIESTA are able to lookup the invocation directory of a tool evaluation and can view its contents (command line, input decks, standard output, standard error, result files, etc.). This is particularly useful when simulators fail for some reason. In such situations the user can determine exactly how the simulator was invoked, and he/she is able to execute the simulator manually in order to identify the cause of the failure.