What is Procfs (/proc)?

The /proc filesystem does not exist on disk — it is generated dynamically by the kernel. Each running process has a directory (/proc/PID/) containing its status, memory maps, file descriptors, command line, and environment. System-wide files include /proc/cpuinfo (CPU details), /proc/meminfo (memory usage), /proc/loadavg (system load), /proc/net/ (network statistics), and /proc/sys/ (tunable kernel parameters). Many Linux commands read from /proc: top reads /proc/stat, free reads /proc/meminfo, and lsof reads /proc/PID/fd. Writing to /proc/sys/ allows runtime kernel tuning (equivalent to sysctl commands).