sysctl command examples

sysctl – configure kernel parameters at runtime

List all kernel parameters

/sbin/sysctl -a

Print a kernel parameter. Example: hostname ketnel parameter

/sbin/sysctl -n kernel.hostname

Set a kernel parameter (-w for write) using sysctl. Example: domain name

/sbin/sysctl -w kernel.domainname="example.com"

Update kernel parameters from a file.

Load kernel parameters from /etc/sysctl.conf. We run this generally when we update sysctl.conf file

/sbin/sysctl -p /etc/sysctl.conf

Dispaly all kernel parameters (-a) matching pattern (–pattern) string “*forward*”

/sbin/sysctl -a --pattern forward

Dispaly all kernel parameters (-a) matching pattern (–pattern) string “*forward”. Same as previous but exact word matching.

/sbin/sysctl -a --pattern forward$

Again a search pattern with ‘or’ (|) combination etc.,

/sbin/sysctl -a --pattern 'net.ipv4.conf.(eth|wlan)0.arp'

Read values from all system directories (–system) and display the parameters that start with (^)  string “net.ipv6”

/sbin/sysctl --system --pattern '^net.ipv6'