$devvkit learn --librarie htop-&-btop-guide

htop & btop Guide

[monitoring][processes][cpu][memory]

System Monitoring

Install

sudo apt install htop btop
brew install htop btop
# Windows: btop via WSL or Process Explorer GUI

htop is the first thing you run on an unfamiliar server. Unlike `top`, it shows a color-coded tree view, mouse support, and lets you send signals (kill, renic) interactively. Press `F5` for tree mode, `F6` to sort by any column, and `F9` to kill a process.

btop is a modern alternative with GPU monitoring, disk I/O graphs, network throughput, and a much prettier TUI. It uses CPU, memory, and disk sensors out of the box. Both have customizable color themes.

Key htop tricks: press `u` to filter by user, `t` for tree view, `H` to hide/show user threads, `K` to hide kernel threads. Setup `F2` columns to show IO rate, disk writes, and swap usage. GUI alternatives: Process Explorer (Windows), Activity Monitor (macOS), GNOME System Monitor.

htop Basics

Start htop— Launch interactive monitor.

htop
htop -u www-data            # Only show www-data user
htop -p 1234,5678           # Only show these PIDs
htop -t                     # Start in tree mode
htop -C                     # Monochrome mode

htop keyboard shortcuts— Most useful keys.

# F5 / t  — Tree view
# F6      — Sort by column
# F9      — Kill process (select signal)
# u       — Filter by user
# H       — Toggle user threads
# K       — Toggle kernel threads
# /       — Search process names
# Space   — Tag process for batch action
# F2      — Setup (columns, colors, meters)

htop tree mode— Parent-child process tree.

# Press F5 to toggle tree view
# See which process spawned which child
# Useful for: finding zombie processes, orphaned children

# Tree from CLI:
htop -t
# Or: ps auxf  (ps tree view in CLI only)

htop Filters

htop: sort by IO— Find disk hogs.

# In F2 Setup → Columns:
# Add "IO read rate" and "IO write rate" (requires lsof)
# Then F6 and select those columns

# Alternative: iotop:
sudo iotop -oP  # Only processes with I/O

htop: find CPU hogs— Processes eating CPU.

# Sort by CPU% (F6 then select PERCENT_CPU)
# Press P to sort by CPU instantly (shortcut)
# Press M to sort by memory instantly
# Press T to sort by TIME+ (cumulative CPU)

btop

btop launch— Launch btop.

btop
btop --utf-force            # Force UTF-8 (better box drawing)
btop --low-color            # Less color (terminal compatibility)

# Inside btop:
# Tab: switch between CPU, MEM, DISK, NET, PROC
# ?: help
# m: menu
# q: quit

btop GPU monitoring— Watch GPU usage.

# btop auto-detects NVIDIA GPUs (nvidia-smi required)
# Tab to PROC screen → GPU column shows utilization
# Or watch directly:
watch -n 1 nvidia-smi --query-gpu=utilization.gpu,memory.used --format=csv

# AMD GPUs: needs amdgpu module
# Intel GPUs: needs intel-gpu-tools

Customization

htop custom config— Persistent settings.

# Config file: ~/.config/htop/htoprc
# Or launch with:
htop -C                       # Start fresh (no config)

# Key settings to enable:
# tree_view=1
# sort_key=PERCENT_CPU
# hide_kernel_threads=1
# highlight_base_name=1
# detailed_cpu_time=1
# cpu_count_from_zero=0

btop themes— Change btop appearance.

# Themes in ~/.config/btop/themes/
# Download from: github.com/aristocratos/btop
# In btop: press m -> Options -> Theme

# Or set theme via env:
BTOP_THEME=nord btop
BTOP_THEME=dracula btop
BTOP_THEME=catppuccin btop