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sysctl.d(5) [centos man page]

SYSCTL.D(5)							     sysctl.d							       SYSCTL.D(5)

sysctl.d - Configure kernel parameters at boot SYNOPSIS
/etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf DESCRIPTION
At boot, systemd-sysctl.service(8) reads configuration files from the above directories to configure sysctl(8) kernel parameters. CONFIGURATION FORMAT
The configuration files contain a list of variable assignments, separated by newlines. Empty lines and lines whose first non-whitespace character is # or ; are ignored. Note that both / and . are accepted as label separators within sysctl variable names. "kernel.domainname=foo" and "kernel/domainname=foo" hence are entirely equivalent. 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. EXAMPLE
Example 1. /etc/sysctl.d/domain-name.conf example: # Set kernel YP domain name SEE ALSO
systemd(1), systemd-sysctl.service(8), systemd-delta(1), sysctl(8), sysctl.conf(5) systemd 208 SYSCTL.D(5)

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SYSTEMD-SYSCTL.SERVICE(8)				      systemd-sysctl.service					 SYSTEMD-SYSCTL.SERVICE(8)

systemd-sysctl.service, systemd-sysctl - Configure kernel parameters at boot SYNOPSIS
/lib/systemd/systemd-sysctl [OPTIONS...] [CONFIGFILE...] systemd-sysctl.service DESCRIPTION
systemd-sysctl.service is an early boot service that configures sysctl(8) kernel parameters by invoking /lib/systemd/systemd-sysctl. When invoked with no arguments, /lib/systemd/systemd-sysctl applies all directives from configuration files listed in sysctl.d(5). If one or more filenames are passed on the command line, only the directives in these files are applied. In addition, --prefix= option may be used to limit which sysctl settings are applied. See sysctl.d(5) for information about the configuration of sysctl settings. After sysctl configuration is changed on disk, it must be written to the files in /proc/sys before it takes effect. It is possible to update specific settings, or simply to reload all configuration, see Examples below. OPTIONS
--prefix= Only apply rules with the specified prefix. -h, --help Print a short help text and exit. --version Print a short version string and exit. EXAMPLES
Example 1. Reset all sysctl settings systemctl restart systemd-sysctl Example 2. View coredump handler configuration # sysctl kernel.core_pattern kernel.core_pattern = |/libexec/abrt-hook-ccpp %s %c %p %u %g %t %P %I Example 3. Update coredump handler configuration # /lib/systemd/systemd-sysctl --prefix kernel.core_pattern This searches all the directories listed in sysctl.d(5) for configuration files and writes /proc/sys/kernel/core_pattern. Example 4. Update coredump handler configuration according to a specific file # /lib/systemd/systemd-sysctl 50-coredump.conf This applies all the settings found in 50-coredump.conf. Either /etc/sysctl.d/50-coredump.conf, or /run/sysctl.d/50-coredump.conf, or /usr/lib/sysctl.d/50-coredump.conf will be used, in the order of preference. See sysctl(8) for various ways to directly apply sysctl settings. SEE ALSO
systemd(1), sysctl.d(5), sysctl(8), systemd 237 SYSTEMD-SYSCTL.SERVICE(8)
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