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Linux
Compression
Compress a folder 
tar -czf archive.tar.gz myfolder/

Creates a gzip-compressed archive
Windows equivalent: Compress-Archive -Path myfolder -DestinationPath archive.zip
Unzip an archive 
tar -xzf archive.tar.gz

Extract the contents of a gzip archive.
Équivalent PowerShell (Windows): Compress-Archive -Path my_folder -DestinationPath archive.zip
Note: tar is also available natively on recent versions of Windows
Filesystem
Display nth CSV field 
cut -d',' -f3 users.csv

This command extracts the third column from the “users.csv” file using a comma as the delimiter
For complex CSV files, use dedicated tools such as csvkit or awk
Show first 10 lines 
head -n 10 logfile.txt

Displays first 10 lines of file.
Windows equivalent: Get-Content logfile.txt -TotalCount 10
Count lines 
wc -l logfile.txt

Counts number of lines in file.
Windows equivalent: (Get-Content logfile.txt).Count
output: 152 logfile.txt
Extract column 
cut -d":" -f1 /etc/passwd

Extracts specific field from CSV.
Windows équivalent: Get-Content file.txt | ForEach-Object { $_.Split(":")[0] }
Recursive search with numbers 
grep -rn "motif" .

Searches recursively with line numbers.
Recursive replacement 
grep -rl 'motif' ./ | xargs sed -i 's/motif/nouveau/g'

Replaces string in all matching files.
Top 10 largest files 
du -ah . | sort -rh | head -n 10

Lists biggest files/directories.
Top 5 frequent lines 
sort file.txt | uniq -c | sort -nr | head -n 5

Shows most common lines in file.
View command history 
history

Displays shell history.
Windows equivalent: Get-History
Logs
View kernel logs 
dmesg | tail -n 20

Displays last kernel messages.
List modified files (24h) 
find . -type f -mtime -1

Shows files modified in last 24 hours.
View service logs 
journalctl -u nginx -n 50

Shows last 50 systemd log entries.
Network
Show network interfaces 
ip addr show

Displays interfaces and IPs.
DNS lookup 
dig example.com

Displays DNS records.
Test network connectivity 
ping -c 3 example.com

Sends ICMP ping packets.
Test port connectivity 
nc -zv host 443

Tests if remote port is reachable.
List open ports 
ss -tuln

Shows open TCP/UDP ports.
Process
Kill process by PID 
kill -9 1234

Force the process with PID 1234 to stop
To get the PID (example for nginx): ps aux | grep nginx | grep -v grep to exclude the grep process from the results.
Or, use a modern command with a regular expression: ps aux | grep [n]ginx
Windows equivalent: Stop-Process -Id 1234 -Force
Run SSH command loop 
for host in server1 server2 server3; do ssh $host "uptime"; done

Runs command on multiple servers via SSH.
Run command in background 
sleep 60 &

Launch a process in the background.
Windows equivalent: Start-Job { Start-Sleep 60 }
List active processes 
ps aux

Shows processes with CPU/memory usage.
Windows equivalent: Get-Process
Monitor process 
top -p <PID>

Monitors live resource usage of a PID.
Scheduling
Run a delayed task 
at now + 5 minutes -f script.sh

Run a script after a delay.
Linux only
Windows equivalent: Start-Sleep 300 ; .\script.ps1
Schedule a recurring task 
crontab -e

Edit the cron table to add scheduled tasks.
Linux only
Windows equivalent: Task Scheduler (GUI) or schtasks
Service
Enable service at boot 
systemctl enable serviceName

Enables auto-start on boot.
Stop - Start - Restart a service 
systemctl start serviceName

e.g: Start a systemd service
Related commands to manage the service
Stop : sudo systemctl stop serviceName
Restart (after configuration changes) : sudo systemctl restart serviceName
Enable at boot : sudo systemctl enable serviceName
Windows equivalent: Start-Service serviceName
Check service status 
systemctl status serviceName

Allows you to check the service's status in real time. It provides detailed status information, the last error, and the PID. Linux only
Check:
Active: active (running) : the service is running
Loaded: ...; enabled; : will start automatically on boot
Windows equivalent: Get-Service serviceName
System
Follow last 5 lines 
tail -f -n 5 fichier.log

Shows last 5 lines and updates in real time.
Tail with line numbers 
tail -f -n +1 app.log | nl

Shows log lines with numbering.
Follow logs in real time 
journalctl -f

Continuously displays newly added lines. It queries the centralised logging daemon directly.
It displays logs from the kernel, the system, and all services (such as Docker, Jenkins, SSH, etc.) in a unified view.
To view real-time monitoring, add the -f
option. Example: monitor a specific service (e.g. Docker): journalctl -u docker -f
Monitor only system errors and alerts: journalctl -p err -f
Monitor kernel logs: journalctl -k -f
Windows equivalent: Get-Content -Path C:\path\to\log -Wait -Tail 50
Top CPU consumers 
ps -eo pid,comm,%cpu --sort=-%cpu | head -n 10

Lists top CPU-consuming processes.
Check folder disk usage 
du -sh *

Displays size of files and directories.
Check disk space 
df -h

Shows disk usage per filesystem.
Check real-time CPU/memory 
top

Shows active processes and resource usage.
Check memory usage 
free -h

Displays total, used and available memory.