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System Monitoring

Monitoring with top​

The top command provides a real-time, text-based system monitoring dashboard, displaying resource usage like CPU, memory, swap, and running processes. you can run top with command like below:

top

Press q to exit.

Understanding top Output​

When you run top, you will see an output like this:

top - 12:34:56 up 2 days,  3:21,  1 user,  load average: 0.45, 0.33, 0.20
Tasks: 195 total,   2 running, 193 sleeping,   0 stopped,   0 zombie
%Cpu(s):  1.3 us,  0.3 sy,  0.0 ni, 98.3 id,  0.1 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  8000000 total,  2200000 free,  3600000 used,  2200000 buff/cache
KiB Swap:  4000000 total,  4000000 free,       0 used.  3000000 avail Mem

Breaking Down top Output​

  • Uptime & Load: Displays system uptime and load averages (CPU workload for the last 1, 5, and 15 minutes).
  • Tasks: Shows the number of running, sleeping, stopped, and zombie processes.
  • CPU Usage: Includes user (%us), system (%sy), idle (%id), and waiting (%wa) CPU time.
  • Memory Usage: Displays total, used, free, and cache memory.
  • Swap Usage: Shows total, used, and available swap space.

top Commands​

  1. Navigation
    • ↑↓ scroll, PgUp/PgDn page scroll, ←→ move fields, Shift+C show index.
  2. Sorting
    • Shift+P CPU, Shift+M memory, Shift+R reverse, f (then s) sort on any field.
  3. Searching/Filtering
    • Shift+L search, o add filter (USER=eric), Ctrl+Oview filters, = clear filters.
  4. Other
    • k kill process, d set refresh rate, Shift+W save settings, m toggle memory view, Shift+E/e change memory scale.

Using btop​

btop is an advanced and visually appealing system monitor that provides detailed CPU, memory, network, disk, and process statistics.

Installing and Running btop​

Use btop​

# Install btop
sudo apt install btop  # Debian/Ubuntu
sudo yum install btop  # RHEL/CentOS
sudo pacman -S btop    # Arch Linux

# Run btop
btop

To exit, press q or Esc.

Understanding btop Output​

btop

When you run btop, the interface consists of multiple sections:

  • CPU Usage : Displays real-time CPU usage per core, average load, and process priority usage. Includes temperature readings (if supported).
  • Memory & Swap Usage : Graphically represents RAM and swap usage, showing cached, free, and used memory.
  • Processes List : Displays process ID (PID), command, CPU/memory usage, and runtime. Supports sorting and filtering.
  • Network Usage : Shows real-time upload/download speeds and total data transferred.
  • Disk Activity : Displays read/write speeds and available/used disk space.

Important btop Commands​

  1. Navigation
    • ↑↓ scroll processes, PgUp/PgDn page scroll.
  2. Sorting
    • ←→ switch sorting (CPU/memory), / search for a process.
  3. Managing Processes
    • DEL/k kill, r change priority, p pause/resume.
  4. View Options
    • Esc toggle views, Shift+E change memory scale.
  5. Settings
    • Shift+W save preferences, F2 open settings menu.