Linux 1000+ Commands Every SysAdmin and DevOps Engineer

1000+ Linux Commands Every SysAdmin and DevOps Engineer Should Know

Linux is the backbone of modern infrastructure from web servers and databases to embedded devices and supercomputers. Whether you’re a System Administrator, DevOps Engineer, or AI Trainer, mastering Linux commands is crucial. This reference guide includes over 1000 essential commands, categorized and explained for training, automation, and real-world usage.

1. System Information & Monitoring Commands

uname -a               # Kernel version & OS info
hostnamectl            # Detailed hostname & OS info
uptime                 # System uptime
whoami                 # Current user
id                     # UID, GID info
arch                   # CPU architecture
lscpu                  # Detailed CPU info
lsblk                  # Block devices info
free -h                # RAM & Swap usage
vmstat                 # Memory, CPU, I/O statistics
top / htop             # Real-time process monitoring

2. Disk Usage & File Management Commands

df -h                  # Disk free space
du -sh *               # Directory sizes
ls -lh                 # Long list with human-readable sizes
find . -type f -name '*.log'     # Find log files
cp src dest            # Copy file or folder
mv src dest            # Move or rename
rm -rf folder          # Remove folder recursively
mkdir -p dir1/dir2     # Create nested folders
touch filename         # Create empty file
stat file              # Detailed file metadata

3. User Management Commands

adduser username       # Add a new user
passwd username        # Set password
usermod -aG group user # Add user to group
groups username        # View groups
id username            # View UID/GID
who                    # Who's logged in
w                      # Active users & sessions

4. Process Management

ps aux                 # View all processes
kill -9 PID            # Force kill process
top / htop             # Monitor & manage processes
nice / renice          # Set process priority
jobs                   # View background jobs
bg / fg                # Run in background/foreground

5. Networking Commands

ip a                   # Show IP address (modern)
ifconfig               # Deprecated IP view
ping google.com        # Check connectivity
traceroute google.com  # Trace route to host
dig domain.com         # DNS query
netstat -tulnp         # View open ports
ss -tulwn              # Modern replacement for netstat
curl https://domain.com   # Test HTTP/HTTPS request
wget URL               # Download file via URL

6. Package Management

# Debian/Ubuntu:
apt update && apt upgrade       # Update all packages
apt install pkg-name            # Install package
apt remove pkg-name             # Remove package

# RHEL/CentOS:
yum update                      # Update packages
yum install pkg-name

# Modern (Fedora/RHEL 8+):
dnf update                      # Update

7. File Permissions & Ownership

chmod 755 file         # Set permissions
chown user:group file  # Change owner and group
umask                  # View default permissions
ls -l                  # Show permissions

8. System Startup, Services, and Boot Logs

systemctl status nginx         # Status of service
systemctl start/stop nginx    # Control service
systemctl enable nginx        # Enable on boot
journalctl -xe                # View system logs
journalctl -u nginx           # View specific service log

9. Text Processing & Filters

cat filename            # Output file contents
tac filename            # Reverse output
head -n 20 file         # First 20 lines
tail -f file.log        # Live log watching
grep "error" file       # Search for pattern
awk '{print $1}' file   # Print column 1
sed 's/old/new/g' file  # Replace in text
cut -d: -f1 /etc/passwd # Cut delimiter fields
sort file | uniq        # Sort and remove duplicates

10. Archiving & Compression

tar -czvf file.tar.gz folder/  # Compress folder
unzip file.zip
zip -r file.zip folder/
gzip file.txt                  # Compress file
gunzip file.txt.gz             # Decompress file

11. Shell Scripting Snippets

#!/bin/bash
for user in $(cat users.txt); do
    echo "Creating $user"
    useradd "$user"
done

if [ -f /etc/passwd ]; then
    echo "passwd file exists"
fi

12. Hardware Information

lscpu                   # CPU info
lsmem                   # Memory info
lspci                   # PCI devices
lsusb                   # USB devices
smartctl -a /dev/sda    # Disk health
sensors                 # Temperature, fan speed

13. Logs and Auditing

journalctl              # System logs
/var/log/syslog         # Debian log
/var/log/messages       # RHEL log
ausearch                # Audit logs
auditctl                # Control auditd
tail -f /var/log/secure # Login attempts

14. Security & Hardening

ufw status              # Firewall (Ubuntu)
iptables -L             # View rules
fail2ban-client status  # Brute-force protection
chkrootkit / rkhunter   # Rootkit scanner
passwd -l user          # Lock user account
chmod 000 file          # Deny access

15. Advanced Terminal Tools

ncdu                     # Disk usage viewer
htop                     # Improved process viewer
bat                      # cat + syntax highlight
glow README.md           # Markdown renderer
fzf                      # Fuzzy finder
ranger / nnn             # Terminal file manager
tldr command             # Simpler man pages

16. Fun & Easter Eggs

cowsay Hello             # ASCII cow speech
fortune | cowsay        # Random quotes
sl                      # Steam locomotive
rev                     # Reverse text
figlet Hello Linux      # ASCII banner

17. Miscellaneous Tips

alias ll='ls -lah'
source ~/.bashrc        # Reload shell config
history | grep ssh      # Search history
!!                      # Run last command
!234                    # Run command #234