cat /proc/cpuinfo: CPU info
cat /proc/meminfo: Current memory info
cat /proc/version: Kernel info, cmd “uname”
cat /proc/cmdline: Kernel start up parameters
cat /proc/uptime: System start up time (in seconds)
cat /proc/mounts: System current mount info
ll /proc/sys: System current setting info
cat /etc/issue: Linux version
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all: disable ping response
/proc/self: current process (link to current PID)
cat /proc/[PID]/cmdline: PID start up parameters
cat /proc/[PID]/cwd: PID current working directory (link to it)
cat /proc/[PID]/environ: PID current env variables. If go to the “self” folder, the SSH client IP:Port will be show as env variable.
cat /proc/[PID]/status: PID status info. Here can check the PID, PPID.
cat /proc/[PID]/limits: PID limitation info
ll /proc/[PID]/fd: List all PID current opening files (link to files)
Refer to sysctl and /etc/sysctl.conf for system info setting.