Running kernel and system information

# uname -a # Get the kernel version (and BSD version)
# lsb_release -a # Full release info of any LSB distribution
# cat /etc/SuSE-release # Get SuSE version
# cat /etc/debian_version # Get Debian version

Use /etc/DISTR-release with DISTR= lsb (Ubuntu), redhat, gentoo, mandrake, sun (Solaris), and so on. See also /etc/issue.

# uptime # Show how long the system has been running + load
# hostname # system's host name
# hostname -i # Display the IP address of the host. (Linux only)
# man hier # Description of the file system hierarchy
# last reboot # Show system reboot history

Hardware Informations

Kernel detected hardware

# dmesg # Detected hardware and boot messages
# lsdev # information about installed hardware
# dd if=/dev/mem bs=1k skip=768 count=256 2>/dev/null | strings -n 8 # Read BIOS

Linux

# cat /proc/cpuinfo # CPU model
# cat /proc/meminfo # Hardware memory
# grep MemTotal /proc/meminfo # Display the physical memory
# watch -n1 'cat /proc/interrupts' # Watch changeable interrupts continuously
# free -m # Used and free memory (-m for MB)
# cat /proc/devices # Configured devices
# lspci -tv # Show PCI devices
# lsusb -tv # Show USB devices
# lshal # Show a list of all devices with their properties
# dmidecode # Show DMI/SMBIOS: hw info from the BIOS

FreeBSD

# sysctl hw.model # CPU model
# sysctl hw # Gives a lot of hardware information
# sysctl vm # Memory usage
# dmesg | grep "real mem" # Hardware memory
# sysctl -a | grep mem # Kernel memory settings and info
# sysctl dev # Configured devices
# pciconf -l -cv # Show PCI devices
# usbdevs -v # Show USB devices
# atacontrol list # Show ATA devices
# camcontrol devlist -v # Show SCSI devices