ps listing processes with the default tool
top listing & ranking processes
htop listing & ranking processes with more options
atop listing & ranking processes with even more options
prtstat gathering process info
pidstat reporting process resource utilisation
prlimit viewing and setting resource limits
pmap viewing memory maps
gstack tracking calls
pstree listing processes in tree format
kill, pkill & killall signaling and killing processes
nice, renice & ionice changing CPU & I/O prioritisation
lsof listing filehandles