I want to put in sudo gedit /etc/sysctl.conf the one line vm.swappiness=10 which I sometimes change.

By default this line doesnt exist so I use echo "vm.swappiness=10" | sudo tee -a /etc/sysctl.conf.

If I would always be putting the same exact line vm.swappiness=10, then in case I want to replace I could use sudo sed -i 's/vm.swappiness=10/vm.swappiness=1/g' /etc/sysctl.conf But since there could be vm.swappiness=12 or something else, I want--with just a single command--to find if, in /etc/sysctl.conf, there exists line starting vm.swappiness=. Then if it does exist I want to remove the whole line (then by appending && echo "vm.swappiness=1" | sudo tee -a /etc/sysctl.conf to that command, it would also subsequently add the new configuration line that I want to the end.

But again since there could be a lot of different parameters in one line, it wouldn't be good to delete it all, but would be better to change only the number (to the immediate right of vm.swappiness=).

What you think? Would it be better to search for vm.swappiness=x(x(x)) with 1 to 3 numbers (of course, 100 also exists...), replace if it's there (by putting it into a variable and using a command like `sudo sed -i 's/$oldline/$newline/g'), and if not then just append vm.swappiness=10?