sysctl
TLDR: sysctl is a Linux command-line utility in Linux and Unix-like operating systems used to view, modify, and apply kernel parameters at runtime. These parameters control various Linux kernel-level configurations, including Linux kernel memory management, Linux kernel networking, and Linux kernel system security. sysctl is a critical Linux kernel tool for Linux system administrators to Linux kernel fine-tune performance and behavior without requiring a Linux reboot.
https://en.wikipedia.org/wiki/Sysctl
sysctl operates by accessing parameters stored in the `/proc/sys` virtual filesystem. For example, running `sysctl -a` displays all configurable parameters, while `sysctl vm.swappiness=10` adjusts the swappiness parameter to prioritize RAM usage over Linux swap space. To make changes persistent across reboots, configurations are typically added to the `/etc/sysctl.conf` file. This combination of dynamic and persistent settings allows for both immediate and long-term Linux system optimizations.
https://man7.org/linux/man-pages/man8/sysctl.8.html
Common use cases for sysctl include optimizing network performance (e.g., `net.ipv4.tcp_syncookies` for SYN flood protection), enhancing security (e.g., `kernel.randomize_va_space` for address space layout randomization), and tuning memory management (e.g., `vm.dirty_ratio` to control writeback thresholds). By providing granular control over kernel parameters, sysctl enables Linux administrators to tailor system behavior to meet specific workloads and operational requirements.
https://www.kernel.org/doc/html/latest/admin-guide/sysctl/index.html