procps 1:3.3.9-1ubuntu8 (amd64 binary) in ubuntu vivid

 This package provides command line and full screen utilities for browsing
 procfs, a "pseudo" file system dynamically generated by the kernel to
 provide information about the status of entries in its process table
 (such as whether the process is running, stopped, or a "zombie").
 .
 It contains free, kill, pkill, pgrep, pmap, ps, pwdx, skill, slabtop,
 snice, sysctl, tload, top, uptime, vmstat, w, and watch.