After reading /etc/security/limits.conf, individual files from the /etc/security/limits.d/ directory are read. The files are parsed one after another in the order of "C" locale. So the order will be special characters, numbers in ascending order, uppercase letters and lowercase letters in alphabetical order. If two files have same entry, then the entry read last will be taken in effect. Only files with *.conf extension will be read from this directory.
Um diretório de fragmentos de configuração oferece a capacidade de vários pacotes fornecerem as configurações necessárias. Um item da lista de discussão da Debian oferece essa percepção:
Once upon a time, most UNIX software was controlled by a single configuration file per software package, and all the configuration details for that package went into that file. This worked reasonably well when that file was hand-crafted by the system administrator for local needs.
When distribution packaging became more and more common, it became clear that we needed better ways of forming such configuration files out of multiple fragments, often provided by multiple independent packages. Each package that needs to configure some shared service should be able to manage only its configuration without having to edit a shared configuration file used by other packages.
The most common convention adopted was to permit including a directory full of configuration files, where anything dropped into that directory would become active and part of that configuration.