Bash System Info Commands - df, du, free, uname, uptime, lsblk

System Information Commands

Monitoring system resources is a core task for system administrators and DevOps engineers. Bash provides several commands for checking disk, memory, CPU, and system details.

Disk Usage with df

df (disk free) shows filesystem-level disk usage:

df -h                  # human-readable output
df -hT                 # include filesystem type
df -h /                # specific mount point
df -i                  # inode usage (file count limits)
df -h --total          # include total row

Directory Sizes with du

du (disk usage) shows per-directory sizes:

du -sh *               # summary of each item in current dir
du -h -d 1             # one level deep
du -sh node_modules/   # single directory total
du -h --max-depth=2 | sort -rh | head -20  # largest directories

Memory with free

free -h                # human-readable
free -m                # megabytes
free -s 5              # refresh every 5 seconds

System Details with uname

uname -a               # all information
uname -r               # kernel release
uname -m               # architecture (x86_64, arm64)
uname -n               # hostname
cat /etc/os-release    # distribution details

Uptime and Load

uptime                 # uptime + load averages
uptime -p              # pretty format
uptime -s              # boot time
cat /proc/loadavg      # load averages + running processes

CPU Information

nproc                          # number of CPU cores
lscpu                          # detailed CPU info
cat /proc/cpuinfo | grep "model name" | head -1

Block Devices

lsblk                 # block device tree
lsblk -f              # with filesystem info
fdisk -l              # partition details (requires root)

Network Interfaces

ip addr                # IP addresses
ip route               # routing table
ss -tlnp               # listening TCP ports

Monitoring Script

#!/usr/bin/env bash
echo "=== System Report $(date) ==="
echo ""
echo "--- Hostname: $(hostname) ---"
echo "--- Uptime: $(uptime -p) ---"
echo ""
echo "=== Disk Usage ==="
df -h | grep -E "^/dev"
echo ""
echo "=== Memory ==="
free -h
echo ""
echo "=== Top 5 Processes by Memory ==="
ps aux --sort=-%mem | head -6
echo ""
echo "=== Load Average ==="
cat /proc/loadavg