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user1046658
Asked: 2020-08-23 08:30:45 +0800 CST

Does sysctl [variable=[value]] have the same effect as sysctl -w [variable=[value]]?

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I know sysctl [variable] such as sysctl vm.swappiness will print out the value of vm.swappiness. But when I tried sysctl vm.swappiness=10 and then typed sysctl vm.swappiness, it showed that vm.swappiness = 10 (it was 60 before). I thought to change a sysctl setting, you had to do sysctl -w [variable] such as sysctl -w vm.swappiness=10.

Is there a difference between sysctl vm.swappiness=10 and sysctl -w vm.swappiness=10?

I thought that sysctl -w vm.swappiness=10 might edit /etc/sysctl.conf directly, but that does not seem to be the case because when I entered sysctl -w vm.swappiness=10 and then looked at /etc/sysctl.conf, vm.swappiness was still set to 60. Then, when I did sysctl -p, vm.swappiness became 60 again.

So additionally, does sysctl -w configure /etc/sysctl.conf in any way?

command-line systemd

1 Answers

  1. Best Answer

    re: Is there a difference between sysctl vm.swappiness=10 and sysctl -w vm.swappiness=10?

    No.

    re: So additionally, does sysctl -w configure /etc/sysctl.conf in any way?

    No.

    To edit /etc/sysctl.conf with a GUI text editor:

    sudo -H gedit /etc/sysctl.conf

    Otherwise use pico, nano, vim, or other favorite editor.

    See man sysctl for more info.

    Be careful when setting vm.swappiness. A low value favors RAM, where a high value favors swap.

    Examples:

    With 4G RAM, setting vm.swappiness=10 is nuts. With a large enough swap, setting vm.swappiness greater than 60 (the default) might make some sense.

    With 32G RAM, and a HDD for swap, setting vm.swappiness=10 might make some sense.

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