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Linux Commands for Cloud Computing

Practical commands for checking memory, disk, and package health on a Linux cloud server (tested on Ubuntu 22.04).

Check Free Memory on Virtual Private Server (VPS)

1. Quick overview

free -h

Look at the available column. It shows memory that can be used without swapping, and it matters more than the free column.

2. Check disk space

Low disk space often shows up together with low memory.

df -h /

sudo du -xhd1 /var 2>/dev/null

sudo journalctl --disk-usage
  • df -h / shows total, used, and free space on the main disk.
  • du -xhd1 /var shows which folders under /var use the most space.
  • journalctl --disk-usage shows how much space system logs take.

3. Check swap

swapon --show

No output means no swap is active.

4. Find which processes use the most memory

ps aux --sort=-%mem | head -n 10

Shows the top 10 processes by memory use.

5. Detailed memory info

head -n 5 /proc/meminfo
vmstat 1 5
  • /proc/meminfo shows total, free, and available memory in detail.
  • vmstat 1 5 prints 5 snapshots, one per second. Watch the si and so columns: values above zero mean the system is swapping.

6. Live view

top

Press M to sort by memory and q to quit.

7. Check for stuck package processes

ps aux | grep -E "apt|dpkg"
sudo dpkg --audit
  • The first command lists running package processes.
  • dpkg --audit reports packages that are half-installed or misconfigured. No output means everything is fine.

!!! Warning

Do not kill package processes or delete lock files until you know what they are.