| Command | Description and/or Reason |
|---|---|
| uname -a | Prints the kernel version, arch, sometimes distro |
| ps aux | List all running processes |
| top -n 1 -d | Print process, 1 is a number of lines |
| id | Your current username, groups |
| arch, uname -m | Kernel processor architecture |
| w | who is connected, uptime and load avg |
| who -a | uptime, runlevel, tty, proceses etc. |
| gcc -v | Returns the version of GCC. |
| mysql --version | Returns the version of MySQL. |
| perl -v | Returns the version of Perl. |
| ruby -v | Returns the version of Ruby. |
| python --version | Returns the version of Python. |
| df -k | mounted fs, size, % use, dev and mount point |
| mount | mounted fs |
| last -a | Last users logged on |
| lastcomm | |
| lastlog | |
| lastlogin (BSD) | |
| getenforce | Get the status of SELinux (Enforcing, Permissive or Disabled) |
| dmesg | Informations from the last system boot |
| lspci | prints all PCI buses and devices |
| lsusb | prints all USB buses and devices |
| lscpu | prints CPU information |
| lshw | list hardware information |
| ex | |
| cat /proc/cpuinfo | |
| cat /proc/meminfo | |
| du -h --max-depth=1 / | note: can cause heavy disk i/o |
| which nmap | locate a command (ie nmap or nc) |
| locate bin/nmap | |
| locate bin/nc | |
| jps -l | |
| java -version | Returns the version of Java. |