How to reload sysctl.conf variables on Linux
I
am new Linux system user. How do I reload all sysctl variables without rebooting my server?
The sysctl command is used to modify Linux kernel variables at runtime. The variables are read and write from /proc/sys/ location using procfs. The syntax is as follows for to define variable:
variable=value
Read variable from command line
Type the following command
$ sysctl kernel.ostype
Sample outputs:
kernel.ostype = Linux
To see all variables pass the -a option:
$ sysctl -a
$ sysctl -a | grep kernel
$ sysctl -a | more
Sample outputs:
abi.vsyscall32 = 1
crypto.fips_enabled = 0
debug.exception-trace = 1
debug.kprobes-optimization = 1
dev.hpet.max-user-freq = 64
dev.mac_hid.mouse_button2_keycode = 97
dev.mac_hid.mouse_button3_keycode = 100
dev.mac_hid.mouse_button_emulation = 0
dev.raid.speed_limit_max = 200000
dev.raid.speed_limit_min = 1000
dev.scsi.logging_level = 0
fs.aio-max-nr = 65536
fs.aio-nr = 5352
fs.binfmt_misc.status = enabled
fs.dentry-state = 1076563 1034844 45 0 0 0
fs.dir-notify-enable = 1
fs.epoll.max_user_watches = 418058
fs.file-max = 204059
fs.file-nr = 1664 0 204059
fs.inode-nr = 280530 70402
fs.inode-state = 280530 70402 0 0 0 0 0
fs.inotify.max_queued_events = 16384
fs.inotify.max_user_instances = 128
fs.inotify.max_user_watches = 8192
fs.lease-break-time = 45
fs.leases-enable = 1
fs.mqueue.msg_default = 10
fs.mqueue.msg_max = 10
fs.mqueue.msgsize_default = 8192
fs.mqueue.msgsize_max = 8192
fs.mqueue.queues_max = 256
fs.nfs.nfs_congestion_kb = 45760
fs.nfs.nfs_mountpoint_timeout = 500
fs.nfs.nlm_grace_period = 0
fs.nfs.nlm_tcpport = 0
fs.nfs.nlm_timeout = 10
…..
..
..
vm.page-cluster = 3
vm.panic_on_oom = 0
vm.percpu_pagelist_fraction = 0
vm.scan_unevictable_pages = 0
vm.stat_interval = 1
vm.swappiness = 60
vm.user_reserve_kbytes = 63568
vm.vfs_cache_pressure = 100
vm.zone_reclaim_mode = 0
Write variable from command line
The syntax is:
# sysctl -w variable=value
To enable packet forwarding for IPv4, enter:
# sysctl -w net.ipv4.ip_forward=1
Reload settings from all system configuration files
Type the following command to reload settings from config files without rebooting the box:
# sysctl –system
The settings are read from all of the following system configuration files:
/run/sysctl.d/*.conf
/etc/sysctl.d/*.conf
/usr/local/lib/sysctl.d/*.conf
/usr/lib/sysctl.d/*.conf
/lib/sysctl.d/*.conf
/etc/sysctl.conf
Persistent configuration
You need to edit the /etc/sysctl.conf file for setting system variables:
# vi /etc/sysctl.conf
Modify or add in the file. Close and save the file. To Load in sysctl settings from the file specified or /etc/sysctl.conf if none given, enter:
# sysctl -p
