mjhjmtu

I read the current ip address with following command line. after then i need to replace the last value with 0/24
For example. The current ip ist 192.168.178.1 and i need to replace the var value in 192.168.178.0/24

Thank you for your support and best greetings!

 varip=$(ip addr | grep 'state UP' -A2 | tail -n1 | awk 'print $2' | cut -f1 -d'/' )

Use the following sed code at the end:

sed 's:[^.]*$:0/24:'

It works by replacing the last occurring sub-string that doesn't contain '.', with '0/24'. Note how I use ':' as separator for the sed command s, so that I can use '/' un-escaped.

Or go with sed all the way :)

ip addr | sed -rn '/state UP/n;n;s:^ *[^ ]* *([^ ]*).*:1:;s:[^.]*$:0/24:p'

Try this:

ip addr | grep 'state UP' -A2 | tail -n1 | awk 'print $2' | cut -f1 -d'/' | sed 's/.[0-9]*$/.0/24/'

But you do not need cut, replace it with sed:

ip addr | grep 'state UP' -A2 | tail -n1 | awk 'print $2' | sed 's/.[0-9]*//.0//'

This command return the same output.

And you do not need tail, replace it with sed too:

ip addr | grep 'state UP' -A2 | awk 'print $2' | sed '$!d;s/.[0-9]*//.0//'

But the shortest way is to use hostname instead:

hostname -I | tr -d " " | sed 's/[0-9]*$/0/24/'

Output will be the same.

To get Your-IP-Adress/24 use the following command:

ip addr | grep inet | egrep /24 | awk 'print $2'

Here is a perl one liner:

perl -MSys::Hostname -MEnv -e ' print join ".",( unpack("C4",(gethostbyname($HOSTNAME))[4]))[0..2],"0/24n";'

It is predicated on the HOSTNAME environmental variable being set to the proper machine name.

Just using Awk:

ip a | awk '/state UP/nr[NR+2]; NR in nr gsub(/.([0-9]+)/([0-9]+)/,".0/24"); print $2'