Advanced Command Line Tools

The UNIX-like operating systems, including FreeBSD, OpenBSD, and Linux distributions like Rocky Linux and Debian Linux, offer an extensive range of commands that cater to virtually every need of system administration, file manipulation, and performance monitoring. Beyond the commonly used commands like ls, cd, ps, top, and grep, there exists a treasure trove of lesser-known but highly useful commands. This chapter will delve into some of these uncommon commands across FreeBSD, OpenBSD, and Linux, shedding light on their functionalities and potential uses.

FreeBSD and OpenBSD Commands

sockstat (FreeBSD) / fstat (OpenBSD)

  • Use: Display active sockets and file statistics.
  • Why It's Useful: These commands are invaluable for network troubleshooting and monitoring, offering insights into which processes are using network sockets or files.

usbconfig (FreeBSD) / usbdevs (OpenBSD)

  • Use: Provide information about USB devices.
  • Why It's Useful: Essential for diagnosing issues with USB devices or for system inventory purposes, these commands allow administrators to list and manipulate USB devices on the system.

procstat (FreeBSD)

  • Use: Display detailed statistics about processes.
  • Why It's Useful: Beyond what ps offers, procstat can show information about file descriptors, virtual memory usage, threads, and more, making it a powerful tool for in-depth process analysis.

jls and jexec (FreeBSD)

  • Use: Manage jails in FreeBSD.
  • Why It's Useful: jls lists active jails, and jexec executes commands inside jails. These are crucial for managing FreeBSD's lightweight virtualization technology.

doas (OpenBSD)

  • Use: Execute commands as another user.
  • Why It's Useful: Similar to sudo but with a simpler configuration, doas is the default command for privilege escalation in OpenBSD, emphasizing security and simplicity.

Linux Commands (Rocky and Debian Linux)

ncdu (Ncurses Disk Usage)

  • Use: Disk usage analyzer with an ncurses interface.
  • Why It's Useful: Provides a fast, easy-to-navigate interface to see what's consuming disk space, making it simpler to identify and remove large, unnecessary files.


  • Use: Versatile resource statistics tool.
  • Why It's Useful: Combines features of multiple tools like vmstat, iostat, and ifstat, providing a comprehensive view of system resources in real-time.


  • Use: Get or set the I/O scheduling class and priority for a program.
  • Why It's Useful: Allows for fine-tuned control over the disk I/O priority of processes, improving system responsiveness or ensuring critical tasks have priority access to disk resources.


  • Use: List hardware configuration.
  • Why It's Useful: Offers detailed information about all hardware, helping with system audits, troubleshooting, and when performing upgrades.


  • Use: Utility to investigate sockets.
  • Why It's Useful: Replaces and extends the capabilities of the older netstat, providing more detailed information about socket connections with faster execution time.

tmux or screen

  • Use: Terminal multiplexer.
  • Why It's Useful: Allows for multiple terminal sessions within a single window, preserving sessions between connections, and offering a robust way to manage multiple tasks simultaneously.

While the most commonly used UNIX-like commands offer great utility, the less familiar commands discussed here can significantly enhance system administration, troubleshooting, and performance monitoring tasks. By incorporating these tools into their repertoire, system administrators and power users can uncover new efficiencies and insights within FreeBSD, OpenBSD, and Linux environments. Whether managing network connections, investigating hardware details, or optimizing process priorities, the depth and breadth of available commands ensure that there's always a tool for the task at hand.