файлы конфигурации разрешения сетевых имен (Network Name Resolution configuration files)
Конфигурационные каталоги и предшественники (Configuration directories and precedence)
The default configuration is set during compilation, so
configuration is only needed when it is necessary to deviate from
those defaults. Initially, the main configuration file in
/etc/systemd/ contains commented out entries showing the defaults
as a guide to the administrator. Local overrides can be created
by editing this file or by creating drop-ins, as described below.
Using drop-ins for local configuration is recommended over
modifications to the main configuration file.
In addition to the "main" configuration file, drop-in
configuration snippets are read from /usr/lib/systemd/*.conf.d/,
/usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/.
Those drop-ins have higher precedence and override the main
configuration file. Files in the *.conf.d/ configuration
subdirectories are sorted by their filename in lexicographic
order, regardless of in which of the subdirectories they reside.
When multiple files specify the same option, for options which
accept just a single value, the entry in the file sorted last
takes precedence, and for options which accept a list of values,
entries are collected as they occur in the sorted files.
When packages need to customize the configuration, they can
install drop-ins under /usr/. Files in /etc/ are reserved for the
local administrator, who may use this logic to override the
configuration files installed by vendor packages. Drop-ins have
to be used to override package drop-ins, since the main
configuration file has lower precedence. It is recommended to
prefix all filenames in those subdirectories with a two-digit
number and a dash, to simplify the ordering of the files.
To disable a configuration file supplied by the vendor, the
recommended way is to place a symlink to /dev/null in the
configuration directory in /etc/, with the same filename as the
vendor configuration file.
