Common commands include: `ls` (list files), `cd` (change directory), `mkdir` (make directory), `rm` (remove files), `cp` (copy files), `mv` (move files), `cat` (concatenate files), `grep` (search for patterns), `find` (find files), `ps` (process status), `kill` (kill processes), `df` (disk free space), `du` (disk usage), `top` (system monitoring), `ping` (network connectivity), and `ssh` (secure shell).