Sysctl.d
https://www.unix.com/man-page/centos/5/sysctl.d/
目录 /etc/sysctl.d
以及如下目录:
/etc/sysctl.d/*.conf
/run/sysctl.d/*.conf
/usr/lib/sysctl.d/*.conf
Configure kernel parameters at boot,均用来在系统启动时配置内核参数
At boot, systemd-sysctl.service(8) reads configuration files from the above directories to configure sysctl(8) kernel parameters.
Each configuration file shall be named in the style of program.conf. Files in /etc/
override files with the same name in /usr/lib/ and /run/. Files in /run/ override files
with the same name in /usr/lib/. Packages should install their configuration files in
/usr/lib/. Files in /etc/ are reserved for the local administrator, who may use this logic
to override the configuration files installed by vendor packages. All configuration files
are sorted by their filename in lexicographic order, regardless of which of the
directories they reside in. If multiple files specify the same variable name, the entry in
the file with the lexicographically latest name will be applied. It is recommended to
prefix all filenames with a two-digit number and a dash, to simplify the ordering of the
files.
If the administrator wants to disable a configuration file supplied by the vendor, the
recommended way is to place a symlink to /dev/null in /etc/sysctl.d/ bearing the same
filename.