/etc/security/limits.conf Concept https://wiki.archlinux.org/index.php/Limits.conf
/etc/security/limits.conf allows setting resource limits for users logged in via PAM. This is a useful way of preventing, for example, fork-bombs from using up all system resources.
Note: The file does not affect system services. For systemd services the files /etc/systemd/system.conf, /etc/systemd/user.conf, and /etc/systemd/<systemd_unit>/override.conf control the limit. See the systemd-system.conf(5) man page for details.
Config sample https://linux.die.net/man/5/limits.conf
* soft nofile 160000 The syntax of the lines is as follows:
PGP and GPG PGP - Pretty Good Privacy GPG - GNU Privacy Guard oder GnuPG https://en.wikipedia.org/wiki/Pretty_Good_Privacy
The Free Software Foundation has developed its own OpenPGP-compliant program called GNU Privacy Guard (abbreviated GnuPG or GPG).
Install GPG on MacOS Installing homebrew first
Refer to https://blog.ghostinthemachines.com/2015/03/01/how-to-use-gpg-command-line/
And install it.
brew install gnupg Use GPG keygen Generate a key pair
gpg --gen-key Real name: My Realname Email Address: foo@bar.com (Okay) (Enter the pass) As a default, the key type is RSA 2048.