Cada vez que executa um algoritmo, a informação do processo é armazenado no gestor histórico. Juntamente com os parâmetros usados, a data e o tempo de execução são também guardados.
This way, it is easy to track and control all the work that has been developed using the Processing framework, and to reproduce it.
The history manager is a set of registry entries grouped according to their date of execution, making it easier to find information about an algorithm executed at any particular moment.
Figure Processing 31:
A informação do processo é mantida como uma expressão de linha de comandos, mesmo se o algoritmo seja lançado a partir da barra de ferramentas. Isto permite ser útil para aqueles que querem aprender como se usa a interface da linha de comandos, uma vez que podem chamar o algortimo usando a barra de ferramentas e verificar o gestor histórico para ver como o mesmo algoritmo pode ser chamado a partir da linha de comandos.
Apart from browsing the entries in the registry, you can also re-execute processes by simply double-clicking on the corresponding entry.
The history dialog only contains the execution calls, but not the information produced by the algorithm when executed. That information is written to the QGIS log, in a Processing tab.
Third-party algorithms are usually executed by calling their command-line interfaces, which communicate with the user via the console. Although that console is not shown, a full dump of it is written to the log each time you run one of those algorithms. To avoid cluttering the log with that information, you can disable it for each provider, looking for the corresponding option in the provider entry of the settings dialog.
Some algorithms, even if they can produce a result with the given input data, might add comments or additional information to log if they detect potential problems with the data, in order to warn you. Make sure you check those messages in the log if you are having unexpected results.