System information
Print real and effective user and group IDs
id
Show who is logged on and what they are doing
w
Show list block devices
lsblk
Display information about the CPU architecture
lscpu
Show the topology of the system
lstopo
Display amount of free and used memory in the system
free -h
Show certain LSB (Linux Standard Base) and Distribution information.
lsb_release -a
Show distribution information.
cat /etc/*-release
cat /proc/version
cat /etc/issue
Show the status of modules in the Linux Kernel
lsmod
Show Posix IPC
ipcs -ma
Get distribution ID
https://unix.stackexchange.com/a/432819/440845
awk -F= '$1=="ID" { print $2 ;}' /etc/os-release | sed s/\"//g
Information about commands
command -v <command>
type <command>
type -t <command>
type -a <command>
Show the system shutdown entries and run level changes.
who -b
last -xF | head | tac
ausearch -i -m system_boot,system_shutdown | tail -4
journalctl --list-boots
journalctl -b <reboot id> -n
journalctl | grep -i "reboot\|shutdown"
grep -i "reboot\|shutdown" /var/log/messages
Show CPU caches
lscpu --caches