sysctl

# determine the maximum size of a shared memory segment
cat /proc/sys/kernel/shmmax
 
# set default shared memory limit for shmmax (16 GB)
echo 17179869184 > /proc/sys/kernel/shmmax
 
# add the following line to /etc/sysctl.conf to make a change permanent
echo "kernel.shmmax=4294967296" >> /etc/sysctl.d/90-shmmax.conf
 
# load parameter
/sbin/sysctl -p /etc/sysctl.d/90-shmmax.conf

# get swappiness
cat /proc/sys/vm/swappiness
 
# set swappiness
echo "vm.swappiness = 1" > /etc/sysctl.d/90-swap.conf
 
# disable IPv6
echo "net.ipv6.conf.all.disable_ipv6 = 1" > /etc/sysctl.d/01-disable-ipv6.conf
 
# load kernel settings from all system configuration files
sysctl --system
 
# load settings from default configuration /etc/sysctl.conf
sysctl -p
 
# load settings from specified file
sysctl -p /etc/sysctl.d/filename.conf
 
# limit
sysctl net.inet.icmp.icmplim=2000